Cider Vinegar by NOW

Acne. Although there has been interest in using topical apple cider vinegar for acne, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Athletic performance. It is unclear if oral apple cider vinegar is beneficial for improving endurance during exercise. Details: Preliminary clinical research in a small number of healthy male athletes shows that drinking apple cider vinegar 500 mL one-hour prior to an endurance cycling test does not improve endurance capacity, as measured by respiratory exchange rate, heart rate, or blood levels of ammonia, glucose, or lactate, when compared with a commercial sports drink (103225). It is unknown if apple cider vinegar would improve endurance when compared with a placebo control.
Atopic dermatitis (eczema). Although there has been interest in using topical apple cider vinegar for eczema, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Cognitive function. Although there has been interest in using oral apple cider vinegar to improve cognitive function, there is insufficient reliable information about the clinical effects of apple cider vinegar for this use.
Coronavirus disease 2019 (COVID-19). Although there has been interest in using oral apple cider vinegar for COVID-19, there is insufficient reliable information about the clinical effects of apple cider vinegar for this use.
Dandruff. Although there has been interest in using topical apple cider vinegar for dandruff, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Dental plaque. It is unclear if topical apple cider vinegar prevents the accumulation of dental plaque. Details: A small clinical study in children aged 3-6 years with cerebral palsy shows that applying apple cider vinegar 5% to their teeth daily for 6 months reduces the accumulation of dental plaque when compared with manual tooth brushing without dental paste (111228). However, the validity of these findings is limited by a lack of blinding and poor study methodology.
Depression. Although there has been interest in using oral apple cider vinegar for depression, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Diabetes. It is unclear if oral apple cider vinegar is beneficial for improving glucose control in patients with type 2 diabetes; evidence is conflicting. Details: Two meta-analyses of mainly lower-quality clinical trials in a variety of populations (i.e., healthy, overweight, or obese individuals or those with type 2 diabetes) show that taking apple cider vinegar daily for up to 12 weeks reduces fasting blood glucose (FBG) levels by about 8-21 mg/dL, glycated hemoglobin (HbA1c) by 0.5%-0.9%, and total cholesterol by 6-7 mg/dL when compared with control (e.g., water, another beverage, no beverage, or restricted calorie diet). There was no effect on levels of low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, insulin, or on measures of insulin resistance. However, in sub-group analyses limited to patients with type 2 diabetes, the effect of apple cider vinegar on FBG or HbA1c levels is conflicting (106284,112355). Of note, both meta-analyses include studies with heterogeneous populations, varied dosages, and different durations that limit the interpretation of these pooled results. Additionally, a very small clinical study shows that taking apple cider vinegar 20 grams with a meal increases postprandial insulin sensitivity and reduces postprandial flux in insulin levels in patients with insulin resistance, but not those with type 2 diabetes, when compared with placebo (17614). It is unclear if the formulation of apple cider vinegar alters its effects. One small crossover study in healthy adults found a modestly greater reduction in postprandial glucose with the use of liquid apple cider vinegar (providing 1.25 grams acetic acid) when compared with apple cider vinegar whole tablets or crushed tablets (providing 1.5 grams acetic acid) or water alone (106285). Larger studies are needed to confirm this finding.
Dyspepsia. Although there has been interest in using oral apple cider vinegar for dyspepsia, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Gastroparesis. It is unclear if oral apple cider vinegar is beneficial for gastroparesis. Details: A very small clinical study shows that taking apple cider vinegar 30 mL daily worsens the gastric emptying rate in patients with type 1 diabetes and gastroparesis when compared with drinking water (17609).
Gingivitis. It is unclear if topical apple cider vinegar prevents the development of gingivitis. Details: A small clinical study in children aged 3-6 years with cerebral palsy shows that applying apple cider vinegar 5% to the teeth daily for 6 months reduces gingivitis scores when compared to baseline, with results comparable to manual tooth brushing without dental paste at the end of the study period (111228). However, the validity of these findings is limited by a lack of blinding and poor methodology.
Herpes zoster (shingles). Although there has been interest in using topical apple cider vinegar for shingles, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Hyperlipidemia. Although there has been interest in using oral apple cider vinegar for hyperlipidemia, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Impaired glucose tolerance (prediabetes). Although there has been interest in using oral apple cider vinegar for prediabetes, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Insect bite. Although there has been interest in using topical apple cider vinegar for insect bites, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Intestinal parasite infection. Although there has been interest in using oral apple cider vinegar for intestinal parasite infections, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Kidney stones (nephrolithiasis). It is unclear if oral apple cider vinegar reduces the risk for kidney stones. Details: Some population research suggests that the consumption of fermented vinegar can reduce the risk for kidney stones (97311). However, there is currently no clinical evidence confirming this association, or any studies specifically evaluating the use of apple cider vinegar for this purpose.
Leg cramps. Although there has been interest in using oral apple cider vinegar for leg cramps, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Obesity. It is unclear if oral apple cider vinegar is beneficial for obesity. Details: A small clinical study in overweight and obese adults shows that taking apple cider vinegar 15 mL twice daily for 12 weeks along with a calorie-restricted diet helps control appetite and modestly reduces body weight, body mass index (BMI), and hip girth when compared with a restricted calorie diet alone. Taking apple cider vinegar along with dieting also appears to increase high-density lipoprotein (HDL) cholesterol levels and decrease triglyceride levels, but not low-density lipoprotein (LDL) cholesterol levels, when compared to dieting alone (97310).
Osteoarthritis. Although there has been interest in using oral apple cider vinegar for osteoarthritis, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Pharyngitis. Although there has been interest in using oral apple cider vinegar for pharyngitis, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Rhinosinusitis. Although there has been interest in using oral apple cider vinegar for rhinosinusitis, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Sunburn. Although there has been interest in using topical apple cider vinegar for sunburn, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Vaginal candidiasis. Although there has been interest in using topical apple cider vinegar for vaginal candidiasis, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition.
Warts. Although there has been interest in using topical apple cider vinegar for warts, there is insufficient reliable information about the clinical effects of apple cider vinegar for this condition. More evidence is needed to rate apple cider vinegar for these uses.

CHROMIUM

LIKELY EFFECTIVE

Chromium deficiency. Oral or parenteral chromium is effective for the treatment and prevention of chromium deficiency. Details: Taking chromium orally is effective for preventing and treating symptoms of chromium deficiency, including hyperglycemia, glycosuria, sudden weight loss, peripheral neuropathy, and confusion (7135).

POSSIBLY EFFECTIVE

Diabetes. Oral chromium seems to be modestly beneficial for improving glycemic control in diabetes, especially when used in doses greater than 200 mcg daily and in patients with poorly controlled diabetes. It is unclear if chromium helps to prevent the development of diabetes. Details: Epidemiological research has found that lower toenail chromium levels are associated with an increased risk of diabetes and cardiovascular disease (11908). In 2005, the US Food and Drug Administration (FDA) allowed a qualified health claim stating that chromium picolinate may reduce the risk of type 2 diabetes. However, the FDA has determined that any relationship between chromium picolinate and type 2 diabetes is highly uncertain and is based on limited scientific evidence (102362). Research on the use of chromium for the TREATMENT of type 2 diabetes is conflicting but seems to show modest benefit in some patients. Many small clinical studies show that taking chromium orally decreases fasting blood glucose, postprandial glucose, insulin, and glycated hemoglobin (HbA1C) levels, and increases insulin sensitivity (6867,7137,12390,15169,14440,42628,42638,95097,103745). However, other small clinical studies show that chromium is no better than placebo for improving glycemic indices in patients with diabetes (7060,14325,42679,42707,90059,103746,103749). Some of these studies may not have been adequately powered and some had a high risk of bias. Furthermore, these studies had high heterogeneity related to study population and size, chromium supplementation duration, formulation, and dose, and accepted standards of diabetes care. Multiple meta-analyses pooling results of these small clinical trials also show mixed results (90055,90063,95098,105026,110610). The most recent and comprehensive meta-analyses show that chromium picolinate lowers HbA1C by about 0.6%; while it is unclear if chromium yeast, chromium dinicocysteinate, or chromium with biotin or other natural ingredients are beneficial. Chromium seems to be most beneficial in doses of greater than 200 mcg taken for 12 weeks or longer, and in patients with poorly controlled diabetes with a baseline HbA1C of 8% or greater (90063,105026). There is also speculation that chromium might primarily benefit patients with low chromium levels; however, there has not been an analysis specifically evaluating this population (6867,7058,13725,14325,95098). Some research suggests that chromium might also modestly improve lipid levels in patients with type 2 diabetes (1934,6867,95098). A meta-analysis of randomized clinical trials including patients with type 2 diabetes shows that taking chromium 42-1000 mcg orally daily for 5-26 weeks decreases triglyceride levels by 7 mg/dL and increases high-density lipoprotein cholesterol levels by 2 mg/dL when compared with control. Taking chromium did not affect low-density lipoprotein cholesterol levels. However, the validity of these results is limited by high heterogeneity (110605). In addition, some meta-analyses have failed to demonstrate any effects of chromium on lipid levels (110610). A meta-analysis of randomized clinical trials including patients with type 2 diabetes shows that taking chromium 200-1000 mcg orally daily for 8-25 weeks lowers diastolic blood pressure by 2 mmHg, but not systolic blood pressure or body mass index, when compared with placebo (110607). Preliminary clinical research shows that chromium picolinate might improve metabolic parameters in patients with other forms of diabetes as well. This includes those with type 1 diabetes (1935), diabetes secondary to corticosteroid use (5039,42829), and gestational diabetes (42817).

POSSIBLY INEFFECTIVE

Hypertension. Meta-analyses of small clinical trials suggest that oral chromium does not lower blood pressure by a clinically meaningful amount. Details: A meta-analysis of randomized clinical trials in adults with different metabolic disorders shows that taking chromium 42-1000 mcg orally daily for 12-24 weeks does not lower systolic or diastolic blood pressure when compared with placebo (110609). A meta-analysis of randomized clinical trials in adults with different chronic disorders shows that taking chromium 42-1000 mcg orally daily for 4-25 weeks lowers systolic and diastolic blood pressure by 3 mmHg and 1 mmHg, respectively, when compared with placebo. However, the validity of this meta-analysis is limited by high heterogeneity (110604). Another meta-analysis of randomized clinical trials including patients with type 2 diabetes shows that taking chromium 200-1000 mcg orally daily for 8-25 weeks lowers diastolic blood pressure by 2 mmHg, but not systolic blood pressure, when compared with placebo (110607). In addition, the validity of these results is limited by inclusion of patients with and without hypertension at baseline (110604,110607,110609).
Impaired glucose tolerance (Prediabetes). Oral chromium does not seem to improve glycemic indices in patients with prediabetes. Details: Some clinical research shows that adults with impaired glucose tolerance do not have improved glycemic parameters or insulin sensitivity after taking chromium picolinate 500-1000 mcg daily for up to 6 months when compared with placebo (13053,42670). Likewise, a small clinical study in elderly patients with impaired glucose tolerance shows that chromium supplements do not improve glucose tolerance or triglyceride or cholesterol levels when compared with placebo (13722). Finally, a preliminary clinical study in overweight or obese adults with prediabetes shows that taking two capsules of a combination product containing chromium, cinnamon, and carnosine (Glycabiane, PiLeJe) daily for 4 months decreases fasting plasma glucose by approximately 4 mg/dL when compared with placebo, but does not improve fasting plasma insulin, measures of insulin sensitivity or resistance, or glycated hemoglobin (HbA1C) (94234). The small effect on fasting plasma glucose is clinically insignificant and may be due to the other ingredients in this product.
Schizophrenia. Oral chromium does not seem to improve psychological measures in patients with schizophrenia. Details: Clinical research in patients with schizophrenia shows that taking chromium polynicotinate 400 mcg daily for 3 months does not affect weight or mental status when compared with placebo (42613).

Antiretroviral-induced insulin resistance. It is unclear if oral chromium is beneficial for preventing antiretroviral-induced insulin resistance. Details: Preliminary clinical research in HIV patients treated with highly active antiretroviral therapy (HAART) shows that taking chromium nicotinate 200 mcg or chromium picolinate 1000 mcg daily for 8-16 weeks may help decrease insulin resistance and increase glucose disposal when compared to baseline (42630,42662). The validity of this finding is limited by the lack of a control group.
Athletic performance. It is unclear if chromium enhances athletic performance, although some research suggests that it may improve body composition when used in conjunction with exercise. Details: One large clinical study shows taking chromium 400 mcg daily, in conjunction with resistance training, can increase weight loss, body fat loss, and lean body mass when compared with placebo and resistance training (6868). However, other, very small clinical studies show that adding chromium picolinate or chromium chloride 177-400 mcg daily to a weight-training program does not improve body composition when compared with weight-training alone (6860,6861,6862,42747). These studies may not have been adequately powered to detect a difference in outcomes.
Atypical depression. It is unclear if oral chromium is beneficial in patients with atypical depression. Details: Preliminary clinical research in patients with atypical depression shows that taking chromium picolinate 400 mcg daily for 2 weeks followed by 600 mcg daily for an additional 6 weeks improves response and remission rates when compared with placebo (10309). However, other clinical research shows that taking elemental chromium 400 mcg in the form of chromium picolinate daily for 2 weeks followed by 600 mcg daily for an additional 6 weeks does not improve most symptoms of atypical depression, although appetite and sexual drive may improve, when compared with placebo (42600).
Beta blocker-induced dyslipidemia. It is unclear if oral chromium is beneficial in patients with dyslipidemia due to beta-blocker use. Details: One small clinical study in patients who take beta-blockers shows that taking glucose tolerance factor (GTF)-chromium 600 mcg daily for 2 months increases high-density lipoprotein (HDL) cholesterol levels by 16%, but does not affect other lipid parameters, when compared with placebo (5040).
Binge eating disorder. It is unclear if oral chromium is beneficial in patients with binge eating disorder. Details: One small clinical study in overweight adults with binge eating disorder shows that taking chromium picolinate 600 or 1000 mcg by mouth daily for 6 months does not affect binge eating frequency, body weight, or depressive symptoms when compared with placebo (90057).
Bipolar disorder. It is unclear if oral chromium is beneficial in patients with treatment-resistant bipolar disorder. Details: Preliminary clinical research in patients with treatment-resistant, rapid-cycling bipolar disorder shows that taking chromium chloride (Hypo-A Chrom, Hypo-A GmbH) 600-800 mcg daily for up to 2 years can decrease the frequency of affective episodes by approximately three episodes annually when compared to baseline (42618). The validity of this finding is limited by the lack of a control group.
Cognitive impairment. It is unclear if oral chromium prevents cognitive impairment. Details: Some clinical research shows that taking chromium picolinate standardized to contain elemental chromium 1000 mcg daily for 12 weeks does not improve memory or depression in elderly patients with mild cognitive impairment when compared with placebo. However, results from neuroimaging scans suggest that chromium increases the activity of certain regions of the brain during memory tasks when compared with placebo (42666).
Hyperlipidemia. Small clinical studies suggest that oral chromium may modestly reduce lipid levels in patients with hyperlipidemia. Details: One small clinical study in patients with atherosclerotic disease shows that taking chromium 250 mcg as chromium chloride daily for 7-16 months decreases triglycerides and increases high-density lipoprotein (HDL) cholesterol, but not other lipid parameters, when compared with placebo (7060). Other small clinical studies in adults with hyperlipidemia show that taking chromium picolinate 200 mcg daily for 6 weeks, chromium polynicotinate 200 mcg twice daily, or brewer's yeast containing 48 mcg elemental chromium daily for 6-8 weeks decrease total and low-density lipoprotein (LDL) cholesterol when compared to baseline (37178,42585,42710). The validity of this finding is limited by the lack of comparison with a control group. A meta-analysis of small heterogeneous clinical studies in patients mostly without hyperlipidemia shows that taking chromium orally does not affect lipid levels when compared with placebo (105029). A meta-analysis of randomized clinical trials including patients with type 2 diabetes shows that taking chromium 42-1000 mcg orally daily for 5-26 weeks modestly improves triglyceride and HDL cholesterol levels, but not LDL cholesterol levels, when compared with control. However, the validity of these results is limited by high heterogeneity and inclusion of patients with and without hyperlipidemia (110605). In addition, some meta-analyses have failed to demonstrate any effects of chromium on lipid levels in adults with diabetes (110610). Limited research has tested high-dose chromium in children. One small clinical study in children with hypercholesterolemia shows that taking chromium polynicotinate 400-600 mcg with glucomannan 1000-1500 mg twice daily for 8 weeks reduces total and LDL cholesterol when compared to baseline (90061). It is unclear if this effect is due to chromium, glucomannan, or the combination. Finally, chromium does not seem to reduce lipid levels in people without hyperlipidemia.
Hypoglycemia. It is unclear if oral chromium helps to reverse or prevent hypoglycemia. Details: One very small clinical study in patients with reactive hypoglycemia shows that taking chromium chloride 200 mcg daily for 3 months increases blood glucose levels and improves insulin binding and hypoglycemic symptoms following an oral glucose load (6859). Another small clinical study in patients with symptomatic hypoglycemia shows that taking chromium yeast (Biochrome, Pharma-Nord) 125 mcg daily for 3 months improves symptoms, including chilliness, trembling, and disorientation, when compared with baseline (42711). The validity of this finding is limited by the lack of a control group.
Metabolic syndrome. It is unclear if oral chromium is beneficial in patients with metabolic syndrome. Details: One small clinical study in patients with metabolic syndrome shows that taking a particular chromium picolinate product (Chromax, Nutrition 21) 500 mcg twice daily for 16 weeks does not affect weight, waist circumference, insulin sensitivity, glycated hemoglobin (HbA1C), or lipid levels when compared with placebo (42654).
Myocardial infarction (MI). It is unclear if oral chromium helps to prevent MI. Details: Epidemiological research has found that low toenail chromium concentrations are associated with an increased risk of MI (13728). However, toenail chromium concentrations might not be a reliable predictor of body stores of chromium. There is also no reliable research showing that chromium supplements can prevent MI.
Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral chromium slows NAFLD progression. Details: One small clinical study in patients with NAFLD shows that taking chromium picolinate 200 mcg two times daily after meals for 12 weeks does not affect liver enzyme levels or body weight when compared with placebo (105027).
Obesity. Although some research suggests that oral chromium may increase weight loss, this increase in weight loss is not likely to be considered clinically relevant. Details: Meta-analyses of clinical studies in overweight or obese adults show that taking chromium picolinate 200-1000 mcg daily for 12-16 weeks might result in a cumulative weight loss of about 0.5-1 kg when compared with placebo (90062,90065). However, this small reduction in weight is unlikely to be considered clinically significant. Furthermore, certain small clinical studies in healthy, overweight or obese adults and children show that taking oral chromium 200-1000 mcg daily for 6-24 weeks does not reduce weight when compared with control (6860,13727,17224,42680). Some of these studies may not have been adequately powered to detect a smaller effect. A meta-analysis of randomized clinical trials including patients with type 2 diabetes shows that taking chromium 200-1000 mcg orally daily for 8-25 weeks does not lower body mass index when compared with placebo. However, the validity of these results is limited by inclusion of patients with and without obesity at baseline (110607).
Polycystic ovary syndrome (PCOS). It is unclear if oral chromium improves symptoms of PCOS. Details: One small clinical study in patients with PCOS shows that taking chromium picolinate 1000 mcg daily for 6 months along with diet and exercise counseling decreases body mass index and improves rates of ovulation and regular menstruation when compared with placebo (95094). Also, some clinical research shows that taking chromium picolinate (21st Century HealthCare, Inc. or Nature Made) 200 mcg daily orally for 8 weeks increases insulin sensitivity when compared with placebo (95095,98687). However, other preliminary clinical research shows that taking chromium picolinate 200 mcg daily for 4 months does not affect insulin sensitivity or improve ovulation rates (42603). Although chromium picolinate at doses of less than 1000 mcg might have very small effects on fasting glucose, these doses do not seem to have clinically beneficial effects on fasting glucose, pregnancy rate, or testosterone levels (95094,95095,98687). A lower dose of chromium has also been studied in combination with carnitine. One small clinical study in overweight adults with PCOS shows that taking chromium picolinate 200 mcg daily with carnitine 1000 mg daily for 12 weeks modestly reduces fasting blood glucose, insulin resistance, and body weight, and slightly increases insulin sensitivity, when compared with placebo (103747). However, it is unclear if this benefit is clinically significant. Additionally, it is unclear if these effects are due to chromium, carnitine, or the combination. Carnitine has demonstrated clinical benefit when used alone in PCOS.
Turner syndrome. It is unclear if oral chromium is beneficial in patients with this condition. Details: A small clinical study shows that taking brewer's yeast 30 grams containing chromium 50 mcg daily for 8 weeks might improve abnormalities in glucose and lipid metabolism when compared with baseline in patients with Turner syndrome, a genetic disorder that has a high incidence of diabetes (13729). The validity of this finding is limited by the lack of a comparator group. More evidence is needed to rate chromium for these uses.

GLUCOMANNAN

POSSIBLY EFFECTIVE

Constipation. Glucomannan is generally effective for treatment of constipation in adults, but the efficacy in children is less clear. Details: Clinical research in adults shows that taking glucomannan 1-1.5 grams three times daily orally for 3-5 weeks, sometimes followed by 1 gram twice daily for an additional 4 weeks, can relieve constipation. As a nonabsorbable dietary fiber, glucomannan appears to have a bulk laxative effect (11294,57783,57795,57816). Taking glucomannan 1.45 grams with lactulose 4.2 grams twice daily orally for 1-3 months appears to relieve constipation during pregnancy (57818). In children with constipation, glucomannan can increase the frequency of bowel movements but does not seem to improve stool consistency. A meta-analysis of 3 clinical trials including 122 children with functional constipation shows that glucomannan leads to 1.4 more stools per week but does not improve stool consistency when compared with placebo or a maltodextrin control (97935). Two studies included in this analysis show that taking a specific glucomannan supplement (Dicoplus, Dicofarm) 100 mg/kg once or twice daily (maximum daily dose 5 grams) along with fluids for up to 12 weeks relieves constipation in children (11295,57775). However, the other clinical study included in the analysis shows that taking a different glucomannan supplement (Dicoman Junior, Vitis Pharma) 1.26 grams twice daily for 4 weeks does not improve constipation in children (92005).
Diabetes. Limited clinical research suggests that glucomannan may improve glycemic control and lipid profiles in patients with type 2 diabetes. Details: Taking glucomannan orally seems to reduce serum cholesterol and blood glucose levels in patients with type 2 diabetes (183,11357,11359,57791,57797,57798,112702). Most clinical research shows that a glucomannan dose of 3-15 grams daily for 4-12 weeks may reduce fasting blood glucose (183,11357,57791,57797,111225). Eating cookies containing glucomannan 0.5-0.7 grams per 100 kcal for 3 weeks has also been used (11358,11359,57797). Accordingly, a meta-analysis of 5 mostly small, low-quality clinical studies in adults with type 2 diabetes, that includes several of these studies, shows that taking glucomannan 1.2-15 grams daily for 4-16 weeks modestly improves fasting blood glucose when compared with placebo or wheat bran. This analysis also shows that taking glucomannan modestly improves 2-hour post-prandial glucose, total cholesterol, and low-density lipoprotein (LDL) levels but not triglycerides (112702). In healthy people, adding a specific glucomannan supplement (PolyGlycopleX, InovoBiologic Inc.) as granules, 2.5-7.5 grams before meals, or as capsules 3-6 grams with meals, can reduce the glycemic index of starchy foods (92003,92007). Also, taking this glucomannan product reduces postprandial glucose in a dose-dependent fashion in healthy people (92002,92007). However, the interpretation of this evidence is limited by low-quality research and variations in dosages and formulations.
Hyperlipidemia. Most clinical research shows that glucomannan can reduce cholesterol levels in healthy people and those with hyperlipidemia. Details: Although some conflicting evidence exists (57794), most research shows that taking glucomannan orally can improve lipid levels in healthy adults, children and adults with hyperlipidemia, and adults with diabetes (178,11357,11358,11359,57779,57781,57784,57791,57799,97936)(112702). Meta-analyses of clinical research show that taking glucomannan 2.5-15.1 grams daily for up to 12 weeks can reduce total cholesterol by 19 mg/dL, low-density lipoprotein (LDL) cholesterol by 13-16 mg/dL, non-high-density lipoprotein cholesterol by 12 mg/dL, and triglycerides by 11 mg/dL when compared with a control (57797,97936). Clinical research has not demonstrated a dose-response relationship, and the most common glucomannan doses are 5-10 grams daily for up to 6 weeks for adults and 2-3 grams daily in divided doses for up to 8 weeks for children (11358,11359,57797,97936).

Dumping syndrome. It is unclear if oral glucomannan is beneficial in patients with dumping syndrome. Details: Preliminary clinical research shows that taking glucomannan (Propol, Pharmacia) 2.6 or 5.2 grams as a single dose reduces the incidence of reactive hypoglycemia following an oral glucose load in adult patients with previous gastric surgery (57805). Other preliminary clinical research shows that taking glucomannan improves glucose tolerance, but not glucose absorption, in children experiencing gastric dumping syndrome after gastric surgery (57804).
Hypertension. It is unclear if oral glucomannan is beneficial in patients with hypertension. Details: Preliminary clinical research in patients with hypertension shows that eating cookies containing 0.7 grams of glucomannan per 100 kcal, for a total dose of up to 13 grams of glucomannan daily for 3 weeks, can lower systolic blood pressure by about 7% when compared with placebo (11359).
Hyperthyroidism. It is unclear if oral glucomannan is beneficial in patients with hyperthyroidism. Details: Preliminary clinical research in patients with hyperthyroidism shows that taking glucomannan 1.3 grams twice daily orally, plus methimazole and propranolol for 2 months, reduces serum triiodothyronine (T3) and thyroxine (T4) levels during the first few weeks of therapy, when compared with methimazole and propranolol alone. However, these effects seem to diminish after 6 weeks of therapy (57793).
Metabolic syndrome. It is unclear if oral glucomannan is beneficial for metabolic syndrome. Details: A small crossover study in adults with metabolic syndrome, defined as impaired glucose tolerance, reduced high-density lipoprotein (HDL) cholesterol, elevated serum triglycerides, and moderate hypertension, shows that consuming biscuits containing glucomannan 0.5 grams per 100 kcal (equivalent to approximately 8-13 grams/day) daily for 3 weeks may modestly improve fasting glucose, but does not improve blood pressure or levels of triglycerides or HDL cholesterol when compared with wheat bran biscuits (11358). However, the 2-week washout period between interventions may be too short to detect differences in some outcomes.
Obesity. Although some low-quality research shows that oral glucomannan is beneficial for achieving slight improvements in body weight, other research does not support this. Details: Meta-analyses of clinical research on the use of glucomannan for improving body weight and body composition in adults and children with overweight or obesity show mixed results, with one analysis suggesting that taking glucomannan reduces body weight by around 0.8 kg when compared with placebo (57797), and another showing no improvement in body weight (92014). Reasons for these discrepant findings are not clear, but the discrepancies may relate to differences in the study populations and dosing and duration of glucomannan treatment, as well as the low methodological quality of many studies conducted to date. Similar to the pooled analyses described above, individual clinical study results are also mixed. Several small clinical studies show that taking glucomannan can improve body weight, body mass index (BMI), fat mass, and other measures of body composition in children and adults with overweight or obesity, usually when used in combination with a calorie-restricted diet (180,181,182,183,54240,92008,92010,92011,111224,112701). However, conflicting evidence exists (179,57784,57790,57796,92009,112430). Doses that have been used with positive outcomes in adults are 3-4 grams daily, taken in divided doses, for up to 3 months (181,182,183,92008,112701). In children, doses were 2-3 grams daily for 4 months (180). Specific products evaluated include Propylene TM (Natural Alternatives International), PolyGlycopleX (InovoBiologic, Inc.) 3-5 grams 2-3 times daily for 15 weeks, and. Chrombalance 338 mg before each meal and 226 mg in the afternoon daily for 5 weeks (54240,92010,92011). More evidence is needed to rate glucomannan for these uses.

Acne. Although there has been interest in using topical grapefruit oil for acne, there is insufficient reliable information about the clinical effects of grapefruit for this purpose.
Asthma. It is unclear if oral grapefruit is beneficial in patients with asthma. Details: There is some evidence that consumption of vitamin C-rich citrus fruits, including grapefruit and others, might improve lung function in people with asthma. Intake of citrus fruits 1-2 times weekly has produced this benefit in some studies (6049,6055,6056). However, other studies have shown no benefit (6057,6058).
Atherosclerosis. Although there has been interest in using oral grapefruit to treat or prevent atherosclerosis, there is insufficient reliable information about the clinical effects of grapefruit for this purpose.
Atopic dermatitis (eczema). It is unclear if oral grapefruit seed extract is beneficial in patients with atopic dermatitis. Details: One small, uncontrolled clinical study in patients with atopic dermatitis shows that taking a specific grapefruit seed extract product (ParaMicrocidin, Allergy Research Group) 150 mg three times daily for one month can decrease complaints of constipation, flatulence, and abdominal discomfort, possibly due to changes in intestinal microflora (5866). The validity of these findings is limited by a lack of control group.
Depression. Although there has been interest in using inhaled grapefruit oil as aromatherapy for depression, there is insufficient reliable information about the clinical effects of grapefruit oil for this purpose.
Gingivitis. Although there has been interest in using topical grapefruit oil as a rinse for gingivitis, there is insufficient reliable information about the clinical effects of grapefruit oil for this purpose.
Headache. Although there has been interest in using inhaled grapefruit oil as aromatherapy for headache, there is insufficient reliable information about the clinical effects of grapefruit oil for this purpose.
Hypercholesterolemia. It is unclear if oral grapefruit is beneficial in patients with hypercholesterolemia. Details: One small clinical study in patients with hypercholesterolemia shows that taking capsules containing grapefruit pectin 5 grams three times daily for 16 weeks decreases total cholesterol by 8% and the ratio of low-density lipoprotein (LDL) to high-density lipoprotein (HDL) cholesterol by 10% when compared to baseline (2216). The validity of these findings is limited by the lack of a comparator group.
Hypertriglyceridemia. It is unclear if oral grapefruit is beneficial in patients with hypertriglyceridemia. Details: One small clinical study in patients with hypertriglyceridemia that is not well controlled on statin therapy shows that consuming one red or white grapefruit daily for 30 days reduces total cholesterol by 8% to 15.5% and low-density lipoprotein (LDL) cholesterol by 11% to 20% when compared with placebo. In addition, consuming one red, but not one white, grapefruit daily reduces triglyceride levels by 17% when compared with placebo in these patients (53352).
Intestinal parasite infection. Although there has been interest in using oral grapefruit seed extract for intestinal parasite infections, there is insufficient reliable information about the clinical effects of grapefruit for this purpose.
Lice. It is unclear if topical grapefruit extract is beneficial in children with head lice. Details: One small clinical study in children aged 2-9 years with head lice shows that applying 50 mL of a specific shampoo containing grapefruit extract (Licatack shampoo) to the hair for 10-20 minutes and then rinsing with water and combing can eliminate adult lice. Applying a second application after 10 days seems to help remove any remaining nits (91417). The validity of these findings is limited by a lack of control group.
Obesity. While some small studies suggest that oral grapefruit extract, taken in combination with other citrus extracts, may modestly improve weight loss, the effect of oral grapefruit alone is unclear. Details: One small clinical study in obese adults shows that consuming one and a half fresh grapefruits daily for 12 weeks reduces body weight by 1.3 kg when compared with placebo. Also, although drinking 8 ounces of grapefruit juice or taking grapefruit capsules three times daily for 12 weeks did not improve body weight when compared with placebo in the overall study population, a sub-group analysis of obese adults with metabolic syndrome shows that taking grapefruit capsules or drinking grapefruit juice increases weight loss and improves insulin resistance when compared with placebo (53353). Grapefruit has also been evaluated in combination with other citrus ingredients. Two clinical studies shows that taking a specific combination product (Sinetrol, Fytexia) containing sweet orange, blood orange, and grapefruit extracts for 12 weeks can decrease body weight, body fat percentage, and body mass index (BMI) in otherwise healthy overweight adults (95517,95518). In one study, taking this supplement as 450 mg twice daily for 12 weeks reduced body weight by 1 kg and body fat percentage by 6.5% when compared with placebo. Hip circumference, waist circumference, and blood glucose were also reduced when compared with placebo (95518). In another study, taking this same supplement as 700 mg twice daily for 12 weeks reduced body weight by 5.6 kg, body fat percentage by 5%, and BMI by 2% when compared to baseline. Patients taking placebo experienced no significant improvements from baseline (95517). It is not clear if these effects are due to grapefruit extract, other ingredients, or the combination.
Pharyngitis. Although there has been interest in using topical grapefruit oil as a gargle for pharyngitis, there is insufficient reliable information about the clinical effects of grapefruit oil for this purpose.
Psoriasis. Although there has been interest in using oral grapefruit for psoriasis, there is insufficient reliable information about the clinical effects of grapefruit for this purpose.
Stress. Although there has been interest in using inhaled grapefruit oil as aromatherapy for stress, there is insufficient reliable information about the clinical effects of grapefruit oil for this purpose.
Upper respiratory tract infection (URTI). Although there has been interest in using grapefruit oil as aromatherapy for various upper respiratory tract infections, including influenza and the common cold, there is insufficient reliable information about the clinical effects of grapefruit oil for these conditions.
Vaginal candidiasis. Although there has been interest in using oral and topical grapefruit seed extract for vaginal candidiasis, there is insufficient reliable information about the clinical effects of grapefruit seed extract for this purpose. More evidence is needed to rate grapefruit for these uses.

POSSIBLY INEFFECTIVE

Abortion. Despite traditional use for the induction of second trimester abortion, most research shows that intravaginal laminaria does not significantly reduce time to delivery or improve abortion rates, and it may actually worsen some outcomes when compared with standard of care. Details: One clinical study shows that intravaginal administration of laminaria along with misoprostol does not improve second trimester abortion rates at 24 and 48 hours after treatment initiation when compared with using only misoprostol. Also, using laminaria along with misoprostol does not shorten delivery time when compared with misoprostol alone (95688). Another small clinical study shows that adding intravaginal laminaria to misoprostol therapy significantly increases induction time and the need for opioid analgesics when compared with misoprostol alone (109576). Also, a small clinical study in patients undergoing second trimester abortions shows that intravaginal laminaria increases pain with cervical ripening and induction-to-delivery time when compared with mifepristone (109577). A retrospective study in 126 patients undergoing second trimester abortions has found that intravaginal administration of laminaria (Dilateria, Cooper Surgical) one day before using misoprostol might actually prolong delivery time by about 6 hours and does not improve abortion rates at 24 hours after induction when compared with misoprostol alone (105806). Some research shows that intravaginal administration of laminaria (Dilateria, Milex Products Inc.) one day before using prostaglandin E2 (PGE2) suppositories to induce second trimester abortions shortens the delivery time by about 3 hours when compared with PGE2 suppositories alone; however, the incidence of febrile episodes is about 2.3-fold higher for patients treated with laminaria (94045). Also, one small clinical study shows that intravaginal administration of laminaria the night before a scheduled abortion reduces procedure time by around 4 minutes, increases cervical dilation at the time of abortion, and reduces the need for additional dilation when compared with misoprostol treatment on the day of abortion. However, more patients preferred misoprostol over laminaria (109575). Laminaria has also been compared with a mechanical cervical dilation device, called Dilapan-S. A small clinical study in patients undergoing second trimester surgical abortion shows that intravaginal administration of laminaria for cervical preparation has no effect on pain scores or analgesic use following dilator placement or dilation and evacuation (D&E) when compared with Dilapan-S. The validity of these findings may be limited by the single-blinded nature of the study, as well as significant baseline differences between the treatment groups with respect to vaginal parity (105805).
Parturition. Intravaginal administration of laminaria does not seem to be beneficial for cervical ripening. Details: While some research suggests that intravaginal laminaria might reduce the duration of induction, results are conflicting. Additionally, studies suggest that intravaginal laminaria does not seem to reduce the incidence of birth by caesarean section (8945,95689,102765). Also, a small observational study has found that intravaginal laminaria is associated with a greater risk of endometritis and fetal infectious complications when compared with a control group not receiving laminaria (8945).

Acute radiation syndrome. Although there has been interest in using oral laminaria for acute radiation syndrome, there is insufficient reliable information about the clinical effects of laminaria for this purpose.
Cancer. Although there has been interest in using oral laminaria for cancer prevention, there is insufficient reliable information about the clinical effects of laminaria for this purpose.
Hypertension. Although there has been interest in using oral laminaria for hypertension, there is insufficient reliable information about the clinical effects of laminaria for this purpose.
Obesity. It is unclear if oral laminaria is beneficial in patients with obesity. Details: A small clinical study in overweight Japanese adults shows that taking iodine-reduced laminaria powder 2 grams, providing 1 gram of alginate, three times daily for 8 weeks reduces body fat percentage in males, but not females, when compared with placebo. Laminaria does not affect body weight or body mass index when compared with placebo (109572).
Radiation exposure. Although there has been interest in using oral laminaria to minimize environmental radiation exposure, there is insufficient reliable information about the clinical effects of laminaria for this purpose. More evidence is needed to rate laminaria for these uses.

LIKELY INEFFECTIVE

Alzheimer disease. Lecithin does not improve daily functioning in patients with Alzheimer disease. Details: In patients with Alzheimer disease, taking various types of lecithin, 1.2-45 grams daily for up to 6 months, alone or in combination with various conventional medications, does not improve cognitive function or other measures of disease progression (5149,5151,5152,5156,14817,14823,14825,14837,14838).

Age-related cognitive decline. It is unclear if oral lecithin can slow age-related cognitive decline. Details: A small clinical crossover study in healthy adults aged 64 years and older shows that taking lecithin 26 grams orally daily, alone or in combination with physostigmine, for 5 weeks does not seem to improve memory when compared with placebo (19204).
Anxiety. Although there is interest in using oral lecithin for anxiety, there is insufficient reliable information about the clinical effects of lecithin for this condition.
Atopic dermatitis (eczema). Although there is interest in using oral lecithin for atopic dermatitis, there is insufficient reliable information about the clinical effects of lecithin for this condition.
Bipolar disorder. It is unclear if oral lecithin is beneficial in patients with bipolar disorder. Details: A clinical study in six patients with mania shows that taking lecithin 10 mg three times daily improves symptoms of delusions, incoherent speech, and hallucinations when compared with placebo (14839).
Dry skin. Although there is interest in using topical lecithin for dry skin, there is insufficient reliable information about the clinical effects of lecithin for this condition.
Friedreich ataxia. Small clinical studies suggest that oral lecithin is not beneficial in people with Friedreich ataxia. Details: Preliminary clinical research shows that taking lecithin 25 grams orally daily for 1 month does not have any benefit in people with Friedreich ataxia (59298). Other preliminary clinical research shows that taking lecithin for a longer period of 6 months also does not improve performance (19211).
Hyperlipidemia. Although lecithin may lower cholesterol in healthy people, it does not seem to improve cholesterol levels in people with hyperlipidemia. Details: Some clinical research shows that taking lecithin 20-30 grams daily for up to 11 months decreases cholesterol in healthy people (5147,14820). However, other clinical research shows that lecithin has no effect on low-density lipoprotein cholesterol or total cholesterol levels in people with hyperlipidemia (5148,14820).
Parkinson disease. It is unclear if oral lecithin is beneficial in patients with Parkinson disease. Details: Preliminary clinical research in patients with Parkinson disease shows that taking lecithin 32 grams daily for 8 weeks does not improve symptoms when compared with placebo (19212).
Postoperative pain. It is unclear if oral lecithin is beneficial for reducing postoperative pain. Details: Preliminary clinical research shows that taking lecithin 20 grams prior to surgery increases choline levels, but does not reduce postoperative pain after gynecological surgery, when compared with placebo (91231).
Tardive dyskinesia. It is unclear if oral lecithin is beneficial in patients with tardive dyskinesia. Details: Two small clinical studies in patients with tardive dyskinesia shows that taking lecithin orally for 2 months, alone or in combination with lithium, does not improve symptoms when compared with placebo (14822,14824).
TPN-associated hepatic steatosis. It is unclear if oral lecithin is beneficial in patients with hepatic steatosis associated with long-term total parenteral nutrition (TPN). Details: A small clinical study in patients on long-term TPN with low choline levels suggests that taking lecithin 20 grams orally twice daily for 6 weeks reduces the degree of hepatic steatosis, compared with no significant changes in those taking placebo (5140).
Ulcerative colitis. Oral lecithin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking a disease-specific medical food (Profermin, Nordisk Rebalance) containing lecithin, fermented oats, barley malt, and lactobacillus plantarum, as 250 mL twice daily for 24 weeks, decreases disease activity by over 56% when compared with baseline and leads to remission in 46% of patients with mild-to-moderate ulcerative colitis (91228). Other preliminary clinical research in this population shows that taking Profermin 250 mL twice daily for 8 weeks improves disease activity and remission rate when compared with another medical food (Fresubin Original, Fresenius Kabi) (90271). The effects of lecithin alone are unclear. More evidence is needed to rate lecithin for these uses.

VITAMIN B6

EFFECTIVE

Pyridoxine-dependent epilepsy. Intravenous vitamin B6 is effective for controlling pyridoxine-dependent seizures. Details: Pyridoxine-dependent seizures are a rare type of refractory seizures in neonates that do not respond to anticonvulsant drugs. These seizures are typically controlled within minutes of intravenous administration of pyridoxine, a form of vitamin B6. Pyridoxine-dependent seizures can be due to genetic (autosomal recessive) pyridoxine dependency, or more commonly, a result of the use of high-dose pyridoxine during pregnancy (8197,8198).
Sideroblastic anemia. Oral vitamin B6 is effective for treating hereditary sideroblastic anemia. Details: Taking vitamin B6 (pyridoxine) orally is effective for treating hereditary sideroblastic anemia (15,9518). Taking the active form of vitamin B6 (pyridoxal-5'-phosphate) also seems to be effective in cases in which the patient does not respond to pyridoxine (93049).
Vitamin B6 deficiency. Oral vitamin B6 is effective for preventing and treating vitamin B6 deficiency. Details: Taking oral vitamin B6 can prevent and treat vitamin B6 deficiency (15).

LIKELY EFFECTIVE

Hyperhomocysteinemia. Taking vitamin B6 orally, alone or in combination with folic acid, is effective for reducing hyperhomocysteinemia. Details: Vitamin B6 (pyridoxine) seems to lower homocysteine concentrations when folic acid and vitamin B12 are at physiologic levels or when given with folic acid and vitamin B12 supplements (9451,83042,107136). A combination of vitamin B6 100 mg and folic acid 0.5 mg daily seems to lower homocysteine levels by about 35% and is recommended for people with postprandial hyperhomocysteinemia (1489,9406). Other research shows that taking pyridoxine 50-200 mg daily reduces postprandial homocysteine levels by 32% to 35% (9406,10350). Pyridoxine also seems to reduce homocysteine levels in patients with kidney failure, kidney transplant patients (1489,6884,9414,9415), or patients who receive general anesthesia with nitrous oxide (9481). However, some research in healthy adults suggests that adding pyridoxine to folic acid might not provide any additional benefit over folic acid alone (9400,9405,9409,50145). Hyperhomocysteinemia is considered by some to be an independent risk factor for atherosclerosis, recurrent thromboembolism, deep vein thrombosis, myocardial infarction, and ischemic stroke (1899,3323,9402,9405,9408,9409). However, elevated homocysteine levels may be a marker, as opposed to a cause, of vascular disease (11387,11388). A 5 µmol/L increase in plasma homocysteine increases the risk of cerebrovascular disease by 50% and the odds of coronary heart disease by 60% and 80% in males and females, respectively (9407,9411). However, it is not clear if reducing homocysteine levels results in reduced cardiovascular morbidity and mortality (1489,6883,6884,9308,9400,9405,9409). Folic acid, vitamin B6, and vitamin B12 supplementation can reduce total homocysteine from 13.4 to 11 µmol/L. However, this reduction does not seem to help with secondary prevention of death or myocardial infarction, and some research even suggests an increase in cardiovascular disease (CVD) risk (11387,13482,50423,83050,97619). There is also debate about whether supplementation with homocysteine-lowering B vitamins can reduce the risk of stroke. A number of large clinical studies and meta-analyses show that supplementation with folic acid, vitamin B6, and vitamin B12, alone or in combination, does not reduce the risk of stroke in patients with CVD or impaired renal function (11387,13482,50423,83050,96150). However, a more recent meta-analysis shows that B vitamin supplementation modestly reduces the relative risk of stroke by 10% when compared with placebo in patients at risk for or with a history of CVD (97619). Also, a meta-analysis in patients with a history of stroke shows that B vitamin supplementation modestly reduces the relative risk of stroke recurrence by 13% and the risk of vascular death by 11% when compared with placebo (107136).

POSSIBLY EFFECTIVE

Antipsychotic-induced hyperprolactinemia. It is unclear if oral vitamin B6 is beneficial for patients with antipsychotic-induced hyperprolactinemia. Details: Clinical research in male patients with hyperprolactinemia who are on a consistent antipsychotic dose shows that taking vitamin B6 300 mg twice daily for 16 weeks reduces serum prolactin levels by 68%, compared with 37% in patients taking aripiprazole 5 mg twice daily. Also, 67% of patients taking vitamin B6 had prolactin levels less than 40 mcg/mL versus 2% of those taking aripiprazole (107128).
Kidney stones (nephrolithiasis). Oral vitamin B6 seems to decrease urinary oxalate levels and decrease the risk of kidney stone formation in some patients. Details: There is some evidence that taking vitamin B6 (pyridoxine) orally, alone or in combination with magnesium, can decrease urinary oxalate levels in people with type I primary hyperoxaluria, a hereditary disorder (1201,6437,6438,6439,6440,8548,8549,8550). Additionally, a small clinical study in this population suggests that intravenous pyridoxine hydrochloride can reduce urinary oxalate by 25.5% when compared to baseline (90796). In patients with idiopathic hyperoxaluria, taking a combination of pyridoxine 25mg and magnesium oxide 400 mg for 3 months decreases urinary oxalate by approximately 16%, with 68% of patients experiencing a reduction. However, supplementation is less effective than following a low-oxalate diet, which reduces urinary oxalate in 91% of patients by an average of 31% (107127). There is also preliminary evidence that higher pyridoxine intake in females with no history of kidney stones is associated with decreased risk of kidney stone formation (6441), but this association has not been found in males (6442).
Pregnancy-induced nausea and vomiting. Oral vitamin B6 may reduce nausea and vomiting in some pregnant patients and is sometimes used in combination with doxylamine. Details: While some conflicting evidence exists, most small clinical studies suggest that oral vitamin B6 is effective for improving nausea and vomiting associated with pregnancy when compared with baseline or placebo. However, vitamin B6 may not be as effective as ginger (110459). Two small clinical studies show that taking vitamin B6 (pyridoxine) 25 mg every 8 hours for 3-4 days decreases pregnancy-induced nausea severity and vomiting incidence when compared with placebo (6168,16306). A larger clinical trial shows that taking lower doses of vitamin B6, 10 mg every 8 hours over 5 days, improves pregnancy-induced nausea, but not vomiting, when compared with placebo (6167). A small clinical study in patients with mild to moderate nausea and vomiting shows that taking a higher dose of 40 mg twice daily for 4 days is more effective than placebo, but no better than ginger 500 mg twice daily (99404). The American College of Obstetrics and Gynecology (ACOG) considers vitamin B6 at a dose of 10-25 mg 3 to 4 times daily a first-line treatment for pregnancy-induced nausea and vomiting due to its benign safety profile (111601). However, it is not effective for all patients, such as those with hyperemesis gravidarum, a severe form of pregnancy-induced nausea and vomiting. Adding vitamin B6 20 mg three times daily for 2 weeks to intravenous rehydration, metoclopramide, and thiamine seems to be no more effective than placebo for reducing vomiting in hyperemesis gravidarum (99405). Vitamin B6 is also sometimes used in combination with doxylamine. In fact, a combination of vitamin B6 plus doxylamine (Diclegis or Bonjesta, Duchesnay Inc., and various generics) has been approved by the US Food and Drug Administration (FDA) as a prescription product111601). ACOG recommends vitamin B6 in combination with doxylamine as another first-line treatment option (111601). However, the clinical trial used to obtain FDA approval has some methodological problems, and the significance of the results has been questioned. The improvement in symptom scores seen with Diclegis was less than one point on a 13-point scale, which is unlikely to be clinically significant (97998). Also, some clinical research shows that taking pyridoxine 25 mg and doxylamine 12.5 mg is less effective than ondansetron 4 mg when taken every 8 hours for 5 days. Only 41% of the patients using pyridoxine and doxylamine had a clinically significant reduction in nausea, compared to 92% of patients using ondansetron (90797). The combination of vitamin B6 and doxylamine is also studied with acupuncture. A large clinical study in patients with moderate to severe pregnancy-induced nausea and vomiting conducted in China shows that taking vitamin B6-doxylamine (Diclegis, Duchesnay, Inc) 20 to 40 mg each at bedtime for 14 days in combination with daily acupuncture modestly improves patient-reported nausea and vomiting scores when compared with either intervention alone (111820). However, it is unclear whether this improvement is clinically significant.
Premenstrual syndrome (PMS). Oral vitamin B6 seems to reduce PMS symptoms. Details: There is some evidence that taking vitamin B6 (pyridoxine) orally can improve symptoms of PMS such as breast pain or tenderness (mastalgia) and depression in some patients. Pyridoxine in doses of at least 50 mg daily, plus magnesium oxide 200 mg daily, seems to relieve PMS-related anxiety and other symptoms (8555,39007,82962). Although some clinicians advocate doses of pyridoxine 200-500 mg daily for PMS, doses of 50-100 mg daily seem to work just as well. There is no apparent dose-response curve for PMS, so the lowest effective dose should be used. Higher doses might increase the risk of side effects (3093).

POSSIBLY INEFFECTIVE

Age-related cognitive decline. Oral vitamin B6 does not seem to slow age-related cognitive decline. Details: One clinical trial in elderly people with memory complaints shows that taking a combination of B vitamins, including folic acid 0.8 mg, vitamin B12 0.5 mg, and vitamin B6 (form not specified) 20 mg daily for 24 months reduces cerebral atrophy in the gray matter regions associated with Alzheimer disease by up to seven-fold when compared with placebo. However, this protection does not occur in patients with the lowest average blood levels of homocysteine (90374). Furthermore, other clinical research shows that taking vitamin B6 (pyridoxine) 3-75 mg daily in combination with folic acid and vitamin B12 does not improve cognitive function in elderly adults (14392,50225,50510).
Alzheimer disease. Oral vitamin B6 does not seem to improve cognitive function in patients with Alzheimer disease when used in combination with other B vitamins. Also, oral vitamin B6 does not seem to reduce the risk of developing this condition. Details: Clinical research in patients with probable Alzheimer disease taking routine medications shows that taking vitamin B6 25 mg with folic acid 5 mg and vitamin B12 1 mg daily for 18 months does not have a beneficial effect on cognitive function or the severity of disease when compared with placebo. In this study, all patients were consuming a folate-fortified diet (50319). Also, population research in elderly adults has found that a high intake of vitamin B6 from dietary or supplemental sources is not associated with a decreased risk of Alzheimer disease when compared to lower vitamin B6 intake (13165,15270).
Carpal tunnel syndrome. Oral vitamin B6 does not seem to reduce symptoms of carpal tunnel syndrome. Details: Most research shows that people with carpal tunnel syndrome are not generally deficient in vitamin B6 and do not benefit from taking vitamin B6 supplements (8203,8937,9448,9450,9478,9482). Although early studies by a single group of researchers, as well as anecdotal reports, suggest that taking vitamin B6 may relieve carpal tunnel symptoms, more reliable research has not supported these findings (8202,9445,9447,9449,9483,15955,83086).
Cataracts. Oral vitamin B6 does not seem to slow cataract development. Details: Clinical research in females with existing cardiovascular disease (CVD) or at increased risk of CVD shows that taking a combination of folic acid 2.5 mg, vitamin B6 (form not specified) 50 mg, and vitamin B12 1 mg daily for an average of 7.3 years does not reduce the risk of cataracts when compared with placebo. Furthermore, the risk of cataract extraction was increased by 28% (96149).
Chemotherapy-induced acral erythema. While some conflicting evidence exists, most research suggests that oral or topical vitamin B6 does not seem to prevent or reduce the severity of acral erythema induced by chemotherapy. Details: A meta-analysis of 10 clinical trials and 4 observational studies shows that taking vitamin B6 60-500 mg daily for up to 8 chemotherapy cycles does not prevent chemotherapy-induced acral erythema or reduce the incidence of severe cases when compared with control. Most studies used capecitabine chemotherapy alone or in combination, and one study used pegylated liposomal doxorubicin; however, no subgroup analysis was conducted to differentiate chemotherapy regimens. Results did not seem to vary based on study location, study design, or vitamin B6 dose (104930). However, a more recent preliminary clinical study in patients receiving doxorubicin for multiple myeloma shows that taking vitamin B6 100 mg on the first day of chemotherapy then twice daily for 7 days with each cycle reduces the risk of developing acral erythema by 72%, but does not improve the severity of acral erythema, when compared with no vitamin B6 supplementation (110458). Also, one small, low-quality clinical study suggests that taking vitamin B6 400 mg daily reduces the risk of moderate or severe chemotherapy-induced acral erythema when compared with vitamin B6 200 mg daily; however, the higher dose also seems to be associated with worsened tumor response and increased treatment failure (97620). Topical vitamin B6 has also failed to show benefit. A small clinical study in patients with acral erythema from capecitabine or pegylated liposomal doxorubicin shows that applying vitamin B6 1% cream to affected areas three times daily for 6 weeks does not improve symptoms when compared with placebo (104929).
Colorectal adenoma. Oral vitamin B6 does not seem to reduce the risk of developing colorectal adenomas. Details: Clinical research shows that taking a combination of B vitamins, including folic acid 2.5 mg, vitamin B6 (pyridoxine) 50 mg, and vitamin B12 1 mg, daily for up to 9.2 years does not reduce the risk of colorectal adenoma in females at high risk of cardiovascular disease when compared with placebo (90389).
Eclampsia. Oral or intramuscular vitamin B6 does not seem to reduce the risk of eclampsia. Details: Meta-analyses of limited clinical research in pregnant patients show that taking vitamin B6 (pyridoxine), either as 25 mg daily or a single dose of 100 mg orally or intramuscularly, does not reduce the risk of eclampsia when compared with control (83046,96166).
Osteoporosis. Oral vitamin B6 does not seem to reduce the risk of osteoporotic fractures. Details: Clinical research in patients with cerebrovascular disease shows that taking a combination of B vitamins, including folic acid 2 mg, vitamin B6 (form not specified) 25 mg, and vitamin B12 500 mcg daily for up to 10.5 years does not prevent osteoporotic fractures when compared with placebo (90377). Furthermore, a secondary analysis of two large studies in patients with cardiovascular disease has found that taking vitamin B6 (pyridoxine) 40 mg daily in addition to folic acid and vitamin B12 for 1-3 years is associated with a 42% increased risk of hip fracture over an 11-year period when compared with only folic acid and vitamin B12 (96163). This finding is limited because these studies were not designed to assess the effects of vitamin B6 on fracture risk and the analyses were not adjusted for baseline bone health or fall risk.
Pre-eclampsia. Oral or intramuscular vitamin B6 does not seem to reduce the risk of pre-eclampsia. Details: Meta-analyses of limited clinical research in pregnant patients show that taking vitamin B6 (pyridoxine), either as 25 mg daily or a single dose of 100 mg orally or intramuscularly, does not reduce the risk of pre-eclampsia when compared with placebo (83046,96166).
Preterm labor. Oral or intramuscular vitamin B6 does not seem to reduce the risk of preterm labor. Details: Meta-analyses of limited clinical research in pregnant patients shows that taking vitamin B6 (pyridoxine), either as 25 mg daily or a single dose of 100 mg orally or intramuscularly, does not reduce the risk of preterm labor when compared with placebo (83046,96166).

Acne. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in adults and children with inflammatory acne shows that taking 1-4 tablets of a specific product (NicAzel, Elorac Inc.) containing vitamin B6 (pyridoxine), nicotinamide, azelaic acid, zinc, copper, and folic acid for 8 weeks reduces inflammatory lesions and improves appearance in 88% and 81% of patients, respectively, when compared to baseline (90800). The validity of these findings is limited by the lack of a comparator group.
Age-related macular degeneration (AMD). Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A large-scale clinical study shows that taking vitamin B6 (pyridoxine) 50 mg, vitamin B12 1000 mcg, and folic acid 2.5 mg daily reduces the risk for AMD in females over 40 years of age with a history of cardiovascular disease (CVD) or with risk factors for CVD. Those who took this combination for an average of 7.3 years had a 34% reduced risk of developing AMD and a 41% reduced risk of visually significant AMD when compared with placebo (14620). It is unclear if this effect is due to vitamin B6, other ingredients, or the combination.
Angioplasty. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Some evidence suggests that vitamin B6 (pyridoxine) 10 mg, folic acid 1 mg, and vitamin B12 400 mcg daily can decrease the rate of restenosis in patients treated with balloon angioplasty (8009,9412). However, this combination does not seem to be as effective for reducing restenosis in patients after coronary stenting (8009). An intravenous loading dose of folic acid, vitamin B6 (pyridoxine), and vitamin B12 followed by oral administration of folic acid 1.2 mcg, vitamin B6 (pyridoxine) 48 mg, and vitamin B12 60 mcg daily after bare metal coronary stenting also does not seem to reduce restenosis and might actually increase restenosis (12150,12151). Due to the lack of evidence of benefit and potential for harm, this combination of vitamins should not be recommended for patients receiving coronary stents (12151). It is unclear if any effects are due to vitamin B6, other ingredients, or the combination.
Antipsychotic-induced metabolic side effects. It is unclear if oral vitamin B6, as an adjunct to progesterone, is beneficial in patients with antipsychotic-induced amenorrhea. Details: A small clinical study in females with antipsychotic-induced amenorrhea shows that taking vitamin B6 80 mg three times daily for 1 month plus intramuscular progesterone daily for 5 days increases levels of estradiol and follicle stimulating hormone, reduces prolactin levels, and increases the rate of clinical efficacy, defined as the normalization of menstruation and improvement in endocrine indicators, by 14% when compared with progesterone alone (110457).
Anxiety. It is unclear if oral vitamin B6 is beneficial in patients with anxiety. Details: Clinical research in college students shows that taking vitamin B6 100 mg daily for one month does not reduce anxiety scores when compared with placebo (110453). However, because a diagnosis of anxiety was not a requirement for study participation, it is unclear if these findings can be generalized to patients diagnosed with anxiety.
Asthma. It is unclear if oral vitamin B6 is beneficial in patients with asthma. Details: Preliminary clinical studies show that taking vitamin B6 (pyridoxine) 200-300 mg daily may improve symptoms of asthma in some patients, but not others, when compared with placebo (7064,7065). Studies have yielded conflicting results, with some research suggesting that it may only be beneficial in children with severe asthma (7065). Additionally, some research suggests that theophylline may lower vitamin B6 levels, although it is unclear if vitamin B6 supplementation is beneficial (4522,7066,9503).
Atherosclerosis. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in patients with intermediate risk for coronary heart disease shows that taking a specific supplement (Kyolic, Total Heart Health, Formula 108, Wakunga) containing vitamin B6 12.5 mg, aged garlic extract 250 mg, vitamin B12 100 mcg, folic acid 300 mcg, and L-arginine 100 mg daily for 12 months reduces coronary artery calcium progression when compared with placebo (88385). It is unclear if this effect is due to vitamin B6, other ingredients, or the combination.
Atopic dermatitis (eczema). It is unclear if oral vitamin B6 is beneficial in patients with eczema. Details: A small clinical study in children with eczema shows that taking vitamin B6 (pyridoxine hydrochloride) 50 mg daily for 4 weeks does not reduce symptoms such as redness and itchiness when compared with placebo (83090).
Attention deficit-hyperactivity disorder (ADHD). It is unclear if oral vitamin B6 is beneficial for ADHD. Details: A small crossover study in children with ADHD shows that taking vitamin B6 600 mg, niacinamide and ascorbic acid 3 grams, and calcium pantothenate 1.2 grams daily for 6 weeks does not improve behavior scores when compared with placebo (9957).
Autism spectrum disorder. Although there is interest in using oral vitamin B6 for autism, there is insufficient reliable information about the clinical effects of vitamin B6 for this condition.
Bipolar disorder. It is unclear if oral vitamin B6 is beneficial in patients with bipolar disorder. Details: A small clinical trial in patients with type 1 bipolar disorder who are taking lithium and experiencing an acute episode of mania shows that taking vitamin B6 80 mg daily for 8 weeks does not improve cognitive function or the severity of mania when compared with placebo. Cognitive function was reduced in patients taking vitamin B6; any effect on sleep was unclear (107132).
Cancer. It is unclear if oral vitamin B6 reduces overall cancer risk. Details: Population research has found that higher dietary intake of vitamin B6 is associated with a 22% reduced risk of cancer, including esophageal, pancreatic, gastric, colorectal, and breast cancer. However, when dietary and supplemental vitamin B6 intake is considered, the inverse association between vitamin B6 and cancer risk is weaker and limited to fewer tumor sites. Furthermore, a meta-analysis of 9 clinical studies shows that taking vitamin B6 3-100 mg orally daily for 2-7.3 years, in combination with vitamin B12 and folate, does not reduce the risk of cancer in patients with cardiovascular disease or kidney failure (96164).
Cardiovascular disease (CVD). Oral vitamin B6, taken along with other B vitamins, does not seem to improve secondary prevention of death or myocardial infarction in patients with CVD. However, it might slightly lower the risk of stroke. Details: Overall evidence from clinical research and meta-analyses shows that taking vitamin B6 in combination with folic acid and/or vitamin B12 does not seem to help with secondary prevention of death or myocardial infarction in patients with or at risk for CVD (11387,13482,34540,50423,83050,90379,97619). In fact, some research suggests that long-term supplementation with vitamin B6, folic acid, and vitamin B12 for secondary prevention increases the risk of CVD by 20% despite lowering homocysteine levels by 30% (13482). However, some research shows that taking vitamin B6 in combination with other B vitamins modestly reduces the risk of stroke, although results are conflicting (11387,13482,50423,83050,96150,96165,97619,107136). Additionally, it is unclear which specific combination of B vitamins is optimal for reducing stroke risk and which patients are most likely to benefit. In 2001, prior to the publication of the highest quality research on this topic, the US Food and Drug Administration (FDA) approved a qualified health claim stating that, as part of a well-balanced diet that is low in saturated fat and cholesterol, folic acid, vitamin B6, and vitamin B12 may reduce the risk of vascular disease (102368).
Cognitive function. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A moderate-sized clinical study in healthy adults aged 40-65 years shows that taking a supplement containing vitamin B6, ginkgo leaf, bacopa, and other B vitamins twice daily for 12 weeks does not improve memory or attention when compared with placebo (111334).
Colorectal cancer. It is unclear if oral vitamin B6 reduces the risk of colorectal cancer. Details: A meta-analysis of observational studies suggests that the highest dietary intake of vitamin B6 is associated with a 20% reduced risk of colorectal cancer when compared with the lowest dietary intake. However, this association was not shown in subgroup analyses of studies conducted in Australia, Europe, or North America (111600). The validity of this analysis is limited by the heterogeneity of the included studies.
Dental caries. There is limited evidence on the oral use of vitamin B6 for dental decay during pregnancy. Details: Meta-analyses of limited clinical research show that taking vitamin B6 (pyridoxine), 25 mg daily or a single dose of 100 mg orally or intramuscularly, may reduce the risk of dental decay during pregnancy when compared with placebo (83046,96166).
Depression. It is unclear if oral vitamin B6 reduces the risk of developing depression or improves symptoms of depression. Details: Clinical research in healthy college students shows that taking vitamin B6 100 mg daily for one month does not reduce depression scores when compared with placebo (1104453). However, because a diagnosis of depression was not a requirement for study participation, it is unclear if these findings can be generalized to patients diagnosed with depression. Whether vitamin B6 reduces the risk of developing depression is also unclear. A meta-analysis of population research has found that the highest dietary intake of vitamin B6 is associated with a 19% lower risk of depression when compared with the lowest intake. However, sub-analyses suggest that this association is only relevant in females and not males (107133). In one individual population study in community dwelling older adults included in the analysis, the consumption of at least 1.71 mg of vitamin B6 daily from food was associated with a 43% reduction in the likelihood of becoming depressed when compared with the consumption of 1.33 mg or less daily in females. However, there was no association between vitamin B6 levels and risk of depression in males, and the finding in females was no longer significant when adjusted for total energy intake, since foods rich in vitamin B6 are energy-dense (96168). Another observational longitudinal study in healthy adults starting oral contraceptives containing ethinyl estradiol and levonorgestrel has found that taking vitamin B6 25 mg daily for 6-12 months is associated with a 40% lower risk of depression when compared with no supplementation (90789). Most available studies are cross-sectional in nature, making any conclusions related to causation difficult.
Diabetes. It is unclear if oral vitamin B6 is beneficial in patients with type 2 diabetes or gestational diabetes. Details: Observational research in Chinese adults with type 2 diabetes has found that dietary intake of vitamin B6 in the highest quartile is associated with 53% lower odds of developing cardiovascular disease, defined as a non-fatal myocardial infarction, non-fatal stroke, or hospitalization for unstable angina, when compared with vitamin B6 intake in the lowest quartile (110452). Small clinical studies in patients with gestational diabetes and vitamin B6 deficiency shows that taking vitamin B6 (pyridoxine) 100 mg daily for 2 weeks improves glucose tolerance and blood glucose levels when compared with baseline (82967,83088). However, there is concern that these findings were confounded by dietary alterations. This benefit was not observed in a subsequent small case series in patients with gestational diabetes (22380).
Diabetic neuropathy. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research suggests that taking a combination of B vitamins, including folic acid (L-methylfolate), vitamin B12 (methylcobalamin), and vitamin B6 (pyridoxal-5'-phosphate) for 24 weeks does not improve neural dysfunction based on vibration perception when compared with placebo in patients with diabetic neuropathy. However, taking this combination appears to modestly improve neuropathy symptoms and quality of life related to mental functioning when compared with placebo (90375).
Dysmenorrhea. It is unclear if oral vitamin B6 is beneficial in patients with dysmenorrhea. Details: Preliminary clinical research shows that taking vitamin B6 (form not specified) 200 mg daily reduces pain associated with dysmenorrhea when compared with placebo. However, taking vitamin B6 in combination with magnesium does not reduce pain when compared with placebo (77388).
Fibromyalgia. It is unclear if oral vitamin B6 is beneficial in patients with fibromyalgia. Details: A small clinical study in patients with fibromyalgia shows that taking vitamin B6 80 mg daily for 8 weeks does not improve pain, disease severity, anxiety, depression, or quality of life when compared with placebo (110454).
Gastroenteritis-associated nausea and vomiting. It is unclear if oral vitamin B6 is beneficial in children with gastroenteritis. Details: A small clinical study in children aged 6 months to 12 years with acute viral gastroenteritis shows that taking vitamin B6 (form not specified) does not improve symptoms of dehydration or the frequency of vomiting when compared with placebo (90793).
Hypertension. It is unclear if oral vitamin B6 reduces blood pressure. Details: One small clinical study in patients with essential hypertension shows that taking vitamin B6 (pyridoxine hydrochloride) 5 mg/kg daily for 4 weeks can reduce systolic and diastolic blood pressure when compared with baseline (83091). The validity of this finding is limited by the lack of a control group.
Hypertriglyceridemia. It is unclear if oral vitamin B6 reduces triglyceride levels. Details: Preliminary clinical research shows that vitamin B6 (form not specified) 50 mg daily for 12 weeks does not reduce triglyceride levels in people with hypertriglyceridemia when compared with placebo. However, vitamin B6 appears to decrease total cholesterol and high-density lipoprotein (HDL) cholesterol by approximately 9% in these patients (59028).
Infertility. Although there is interest in using oral vitamin B6 for infertility, there is insufficient reliable information about the clinical effects of vitamin B6 for this condition.
Insomnia. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in healthy adults with self-reported sleep difficulty shows that taking a specific product (LZ Complex3, Sanofi Consumer Healthcare Pty Ltd.) containing vitamin B6, zizyphus extract, hops extract, hydrolyzed milk protein (Lactium), and magnesium oxide nightly, 30 minutes before bed, for 2 weeks does not improve sleep quality, daytime functioning, or physical fatigue when compared with placebo. However, due to the large improvement seen in both the treatment and placebo groups, the effectiveness of this product is unclear (95971).
Isoniazid-induced neuropathy. It is unclear if oral vitamin B6 prevents the development of neuropathy in patients taking isoniazid. Details: Preliminary clinical research in patients taking isoniazid for tuberculosis shows that taking vitamin B6 (pyridoxine) 6 mg daily reduces the development of neuropathy when compared with control (83068).
Lactation. It is unclear if oral vitamin B6 helps to suppress postpartum lactation. Details: A meta-analysis of two small clinical trials shows that taking vitamin B6 (pyridoxine) 400-600 mg daily for 6-7 days postpartum does not suppress lactation when compared with no treatment (83047).
Levetiracetam-induced side effects. While some conflicting evidence exists, several small, low-quality studies suggest that oral vitamin B6 (pyridoxine) may reduce some neuropsychiatric adverse effects related to the use of levetiracetam. Details: In an analysis of case reports, retrospective studies, and a single low-quality prospective study, improvement in levetiracetam-associated neuropsychiatric symptoms occurred in approximately 73% of patients taking pyridoxine (107137). A more recent preliminary clinical trial in children ages 1-17 years shows that taking pyridoxine 10 or 15 mg/kg daily as needed based on symptoms improves behavioral side effects associated with levetiracetam by a small amount when compared with low-dose pyridoxine 0.5 mg/kg daily used as placebo (107124). Also, observational research in children ages 9 months to 14 years has found that taking vitamin B6 is associated with improved behavior and a 44% lower risk of levetiracetam discontinuation when compared with no vitamin B6 supplementation (110455). Some observational research in adults with levetiracetam-associated irritability has found that taking vitamin B6 is associated with an improvement in irritability in 45% of patients when compared to baseline (107129). However, a small clinical trial in adults with epilepsy shows that taking pyridoxine 40 mg daily for 3 weeks does not improve levetiracetam-related psychiatric adverse effects when compared with placebo (110456). This study may have been underpowered to detect differences between groups. Pyridoxine doses used in the studies above have ranged from 50-400 mg daily in children and 40-600 mg daily in adults (107124,107129,107137,110456).
Lung cancer. It is unclear if dietary or oral vitamin B6 reduces lung cancer risk. Details: Epidemiological research has found that higher serum levels of vitamin B6 in male smokers is associated with a lower risk of lung cancer (9454). Also, people with blood levels of vitamin B6 in the top quartile have a modestly lower risk of lung cancer when compared with those whose levels are in the lowest quartile. The association is stronger for males and for people who have smoked (97999). However, other epidemiological research found that increased dietary intake of vitamin B6 is not associated with a reduced risk of lung cancer (96164).
Menopausal symptoms. Although there is interest in using oral vitamin B6 for menopausal symptoms, there is insufficient reliable information about the clinical effects of vitamin B6 for this condition.
Motion sickness. Although there is interest in using oral vitamin B6 for motion sickness, there is insufficient reliable information about the clinical effects of vitamin B6 for this condition.
Nausea and vomiting. It is unclear if oral vitamin B6 is beneficial for nausea and vomiting in patients using oral contraceptives. Details: An observational longitudinal study in healthy females taking oral contraceptives containing ethinyl estradiol and levonorgestrel has found that taking vitamin B6 25 mg daily for 6-12 months is associated with a 43% reduced risk of nausea when compared with no supplementation (90789).
Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral vitamin B6 for patients with NAFLD. Details: A small clinical trial in patients with NAFLD shows that taking vitamin B6 (pyridoxine) 30 mg three times daily for 12 weeks does not reduce levels of liver transaminases or plasma lipids when compared with baseline. However, hepatic fat accumulation was modestly reduced (107130). The validity of this study is limited by the lack of a comparator group.
Obesity. It is unclear if oral vitamin B6 in beneficial in overweight or obese individuals. Details: A small clinical trial in females with a body mass index (BMI) of at least 25 kg/m² shows that taking vitamin B6 as pyridoxine 80 mg daily for 8 weeks reduces fat mass and improves insulin resistance and triglyceride levels by a small amount when compared with placebo. Although some other anthropometric and metabolic indices were improved when compared with baseline, there was no effect of pyridoxine on body weight, visceral adiposity, or other endpoints when compared with placebo (107131).
Overall mortality. It is unclear if oral vitamin B6 reduces the risk of overall mortality. Details: Observational research in US adults has found that dietary intake of vitamin B6 in the highest quintile is associated with a 12% to 21% lower risk of all-cause mortality and a 31% to 44% lower risk of cardiovascular mortality when compared with the lowest quintile of dietary vitamin B6 intake (110451).
Pancreatic cancer. It is unclear if oral vitamin B6 reduces the risk of pancreatic cancer. Details: Observational research has found that higher dietary intake of vitamin B6 is associated with a 37% lower risk of developing pancreatic cancer when compared with lower intake (104927).
Postpartum depression. It is unclear if oral vitamin B6 is beneficial in patients with postpartum depression. Details: Preliminary clinical research in individuals considered at increased risk for postpartum depression, but without clinical depression, shows that taking vitamin B6 80 mg daily from the 28th week of pregnancy until birth, and then 40 mg daily for one month, reduces symptoms of depression 1.5 months after birth when compared with baseline (measured during the third trimester) and when compared with placebo. However, it is unclear if any of the patients included in the study developed postpartum depression, as there were no changes in overall symptoms in patients taking placebo (107126).
Restless legs syndrome (RLS). It is unclear if oral vitamin B6 is beneficial in patients with RLS. Details: A small clinical study in adults with RLS who are beginning treatment with pramipexole shows that also taking vitamin B6 40 mg daily for 2 months moderately improves RLS scores and sleep quality scores when compared with pramipexole and placebo (110052).
Schizophrenia. It is unclear if oral vitamin B6 is beneficial for patients with treatment-resistant schizophrenia. Details: Clinical research in male patients with treatment-resistant schizophrenia who are on a consistent antipsychotic dose shows that adding vitamin B6 300 mg twice daily for 16 weeks modestly improves psychotic symptoms and some measures of cognitive performance when compared with adding aripiprazole 5 mg twice daily (107128). More research is needed to determine if these benefits are clinically relevant.
Seizures. It is unclear if oral vitamin B6 is beneficial for preventing seizures in patients with glycosylphosphatidylinositol (GPI) deficiency. Details: Observational case series in a small number of children and young adults with GPI deficiency has found that taking vitamin B6 20-30 mg/kg daily for 3-12 months is associated with some reduction in seizure frequency in 9 of 13 patients. However, no patient reached seizure freedom (107125,107135). In one case series, treatment for 12 months was associated with modest developmental improvements in almost all patients (107135). The study patient populations were slightly different in terms of age and underlying genetic causes for GPI deficiency.
Sickle cell disease. Oral vitamin B6 has only been evaluated in combination with other B vitamins; its effect when used alone is unclear. Details: Preliminary clinical research in adults with sickle cell disease shows that taking vitamin B6 4.2-6 mg, vitamin B12 4.2-6 mcg, and folic acid 700 mcg daily might lower homocysteine levels. However, it is unknown if this will reduce the risk of endothelial damage in these patients (9324).
Stroke. It is unclear if oral vitamin B6, either alone or with other B vitamins, is beneficial for stroke prevention. Details: There is some debate about whether supplementation with homocysteine-lowering B vitamins, including vitamin B6, can reduce the risk of stroke. A number of clinical studies and meta-analyses show that supplementation with folic acid, vitamin B6, and vitamin B12, alone or in combination, does not reduce the risk of stroke in patients with cardiovascular disease (CVD) or impaired kidney function (11387,13482,50423,83050,96150). However, a more recent meta-analysis of 10 clinical trials, including over 44,000 patients at risk for or with a history of CVD, shows that B vitamin supplementation reduces the relative risk of stroke by 10% when compared with placebo (97619). This meta-analysis differed from some of the earlier analyses due to the inclusion of several additional clinical trials. Also, another meta-analysis of three clinical trials including 9900 patients with a history of stroke shows that B vitamin supplementation reduces the relative risk of stroke recurrence by 13% when compared with placebo, although this finding was determined to have a low level of certainty. Based on two clinical trials, there was also a 17% reduced risk of vascular death and an 11% reduction in the combined risk of stroke, myocardial infarction, and vascular death (107136). In 2001, prior to the publication of the highest quality research on this topic, the US Food and Drug Administration (FDA) allowed a qualified health claim stating that, as part of a well-balanced diet that is low in saturated fat and cholesterol, folic acid, vitamin B6, and vitamin B12 may reduce the risk of vascular disease (102368). Unfortunately, even after the publication of higher quality research, it is still unclear which specific combination of B vitamins is optimal and which patients are most likely to benefit. One network meta-analysis shows that a combination of folic acid and vitamin B6 lowers the risk of stroke more effectively than B vitamin mixtures that include vitamin B12 (96165). However, this analysis is limited because it didn't account for dosing. Exposure to low, but not high amounts, of vitamin B12 (cyanocobalamin) seems to reduce stroke risk (96150).
Tardive dyskinesia. It is unclear if oral vitamin B6 prevents tardive dyskinesia in patients taking neuroleptic drugs. Details: A small clinical study in patients taking neuroleptic drugs for schizophrenia shows that taking vitamin B6 (form not specified) 400 mg daily seems to improve Parkinsonian, dystonic, and dyskinetic symptoms when compared with placebo (8558).
Tourette syndrome. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small, nonblinded clinical study in children aged 4-17 years with untreated Tourette syndrome or with chronic tic disorder and associated symptoms of anxiety shows that taking a liquid nutritional supplement providing vitamin B6 2.8 mg and L-theanine 200 mg daily for 2 months improves scores on the Yale Global Tic Severity Scale, but does not reduce anxiety, when compared with patients receiving psychoeducation (108555). This study may have been inadequately powered to detect a difference between groups.
Vincristine-induced neuropathy. Oral vitamin B6 has only been evaluated in combination with pyridostigmine; its effect when used alone is unclear. Details: A small clinical study in children ages 11 months to 13 years with neuropathy due to vincristine treatment for acute lymphoblastic leukemia, shows that taking vitamin B6 150 mg/m2 and pyridostigmine 3 mg/kg twice daily for 3 months is associated with reduced severity of sensory and motor neuropathy when compared with baseline (104928). The validity of this finding is limited by the lack of a control group. More evidence is needed to rate vitamin B6 for these uses.

Safety view details

Below is general information about the safety of the known ingredients contained in the product Cider Vinegar. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

APPLE CIDER VINEGAR (Apple Cider Vinegar powder)

LIKELY SAFE ...when used orally and appropriately in food amounts.

POSSIBLY SAFE ...when used orally and appropriately, short-term for medicinal purposes. Apple cider vinegar has been safely used in short-term studies for up to 12 weeks (17609,17614,97310).

POSSIBLY UNSAFE ...when used topically. Topical application of apple cider vinegar has been reported to cause chemical burns in at least three patients. Mild skin irritation is common (91662,93074,101172). ...when used orally in large amounts, long-term. A case of hypokalemia, hyperreninemia, and osteoporosis has been reported for a patient who consumed apple cider vinegar 250 mL daily for 6 years (31730).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

CHROMIUM

LIKELY SAFE ...when used orally and appropriately in medicinal amounts, short-term. Chromium has been safely used in doses up to 1000 mcg daily for up to 6 months (1934,5039,5040,6858,6859,6860,6861,6862,6867,6868)(7135,7137,10309,13053,14325,14440,17224,90057,90061)(90063,94234,95095,95096,95097,98687); however, most of these studies have used chromium doses in a range of 150-600 mcg. The Food and Drug Administration (FDA) and Institute of Medicine (IOM) evaluations of the safety of chromium suggest that it is safe when used in doses of 200 mcg daily for up to 6 months (13241,13242).

POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts, long-term. Chromium has been safely used in a small number of studies at doses of 200-1000 mcg daily for up to 2 years (7060,7135,42618,42628,42666,110605,110607,110609). However, the Food and Drug Administration (FDA) and Institute of Medicine (IOM) evaluations of the safety of chromium suggest that it is safe when used in doses of 200 mcg daily for up to 6 months (13241,13242).

CHILDREN: LIKELY SAFE
when used orally and appropriately in amounts not exceeding the daily adequate intake (AI) levels by age: 0-6 months, 0. 2 mcg; 7-12 months, 5.5 mcg; 1-3 years, 11 mcg; 4-8 years, 15 mcg; males 9-13 years, 25 mcg; males 14-18 years, 35 mcg; females 9-13 years, 21 mcg; females 14-18 years, 24 mcg (7135). POSSIBLY SAFE...when used orally and appropriately in amounts exceeding AI levels. Chromium 400 mcg daily has been used safely for up to 6 weeks (42680).

PREGNANCY: LIKELY SAFE
when used orally and appropriately in amounts not exceeding adequate intake (AI) levels. The AI for pregnancy is 28 mcg daily for those 14-18 years of age and 30 mcg daily for those 19-50 years of age (7135).

PREGNANCY: POSSIBLY SAFE
when used orally in amounts exceeding the adequate intake (AI) levels. There is some evidence that patients with gestational diabetes can safely use chromium in doses of 4-8 mcg/kg (1953); however, patients should not take chromium supplements during pregnancy without medical supervision.

LACTATION: LIKELY SAFE
when used orally and appropriately in amounts not exceeding adequate intake (AI) levels. The AI for lactation is 44 mcg daily for those 14-18 years of age and 45 mcg daily for those 19-50 years of age (7135). Chromium supplements do not seem to increase normal chromium concentration in human breast milk (1937). There is insufficient reliable information available about the safety of chromium when used in higher amounts while breast-feeding.

GLUCOMANNAN

LIKELY SAFE ...when used orally as food (11358,11359). Glucomannan powder or flour is often used to enrich noodles in traditional Japanese foods.

POSSIBLY SAFE ...when used orally with at least 250 mL (8 ounces) of water or other fluid. Glucomannan has been safely used in studies lasting up to 4 months (178,179,181,182,11046,11294,11357,11294,54240,57775)(57781,57783,57784,92004,92008,92009,92010,92011,106410). In the European Union, the maximum permitted level in foods is 10 grams/kg (106411).

POSSIBLY UNSAFE ...when used orally without any liquid, especially when in tablet form. There have been reports of choking and esophageal or gastrointestinal obstruction when glucomannan products are taken dry. A safety alert for this has been issued by Health Canada (11293,57785,106410).

CHILDREN: POSSIBLY SAFE
when used orally and appropriately with at least 250 mL (8 ounces) of water or other fluid. Glucomannan has been safely used in children for up to 4 months (179,180,11295,57775,57779,92005,92006,97935).

CHILDREN: LIKELY UNSAFE
when used orally without any liquid, especially when in tablet form. There have been reports of esophageal and gastrointestinal obstruction when glucomannan products are taken dry (11293,57785,106410).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

LIKELY SAFE ...when used orally in amounts commonly found in foods. Grapefruit has Generally Recognized as Safe status (GRAS) in the US (4912).

POSSIBLY SAFE ...when used orally and appropriately for medicinal purposes. A grapefruit seed extract has been safely used in clinical research (5866). In addition, capsules containing grapefruit pectin 15 grams daily have been used in clinical research for up to 16 weeks (2216).

POSSIBLY UNSAFE ...when used orally in excessive amounts. Preliminary population research shows that consuming a quarter or more of a whole grapefruit daily is associated with a 25% to 30% increased risk of postmenopausal breast cancer (14858). Grapefruit juice is thought to reduce estrogen metabolism resulting in increased endogenous estrogen levels. More evidence is needed to validate this finding.

PREGNANCY AND LACTATION:
There is insufficient reliable information available about the safety of using medicinal amounts of grapefruit during pregnancy and lactation; avoid using.

LIKELY SAFE ...when used in amounts found in foods. Laminaria has Generally Recognized as Safe (GRAS) status in the US (94048).

POSSIBLY SAFE ...when iodine-reduced laminaria supplements are used, short-term. Iodine-reduced laminaria powder has been safely used at doses up to 6 grams daily for up to 8 weeks (109572).

POSSIBLY UNSAFE ...when used orally in medicinal amounts. The average laminaria-based supplement might contain as much as 1000 mcg of iodine. Ingesting more than 1100 mcg iodine daily (the tolerable upper intake level) can cause hypothyroidism, hyperthyroidism, or exacerbate existing hyperthyroidism (9556,94046). In addition, some laminaria supplements may contain arsenic (645,10275,15588). There is insufficient reliable information available about the safety of laminaria for its other uses.

PREGNANCY: POSSIBLY UNSAFE
when used intravaginally for cervical ripening; there is an increased risk of parental and neonatal infection (8945).

PREGNANCY: LIKELY UNSAFE
when used intravaginally to induce labor; use has been associated with endometriosis, neonatal sepsis, fetal hypoxia, and intrauterine death (6).

PREGNANCY: UNSAFE
when used orally due to potential hormonal effects (19); avoid using.

LACTATION: LIKELY UNSAFE
when used orally because of potential toxicity (19).

LIKELY SAFE ...when used orally in amounts commonly found in foods. Lecithin has Generally Recognized As Safe (GRAS) status in the US (2619,105544). ...when used orally and appropriately in medicinal amounts. Lecithin has been used safely in doses of up to 30 grams daily for up to 6 weeks (5140,5149,5152,5156,14817,14822,14838,19212). ...when used topically (4914).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in food amounts. Lecithin has Generally Recognized As Safe (GRAS) status in the US (105544). There is insufficient reliable information available about the safety of medicinal amounts of lecithin during pregnancy or lactation; avoid using.

VITAMIN B6

LIKELY SAFE ...when used orally and appropriately in doses that do not exceed the tolerable upper intake level (UL) of 100 mg daily for adults (15). ...when used parenterally and appropriately. Injectable vitamin B6 (pyridoxine) is an FDA-approved prescription product (15).

POSSIBLY SAFE ...when used orally and appropriately in doses of 101-200 mg daily (6243,8558).

POSSIBLY UNSAFE ...when used orally in doses at or above 500 mg daily. High doses, especially those exceeding 1000 mg daily or total doses of 1000 grams or more, pose the most risk. However, neuropathy can occur with lower daily or total doses (6243,8195). ...when used intramuscularly in high doses and frequency due to potential for rhabdomyolysis (90795).

CHILDREN: LIKELY SAFE
when used orally and appropriately (3094).

CHILDREN: POSSIBLY SAFE
when used orally and appropriately in amounts exceeding the recommended dietary allowance (5049,8579,107124,107125,107135).

CHILDREN: POSSIBLY UNSAFE
when used orally in excessive doses, long-term (3094).

PREGNANCY: LIKELY SAFE
when used orally and appropriately. A special sustained-release product providing vitamin B6 (pyridoxine) 75 mg daily is FDA-approved for use in pregnancy. Vitamin B6 (pyridoxine) is also considered a first-line treatment for nausea and vomiting in pregnancy by the American College of Obstetrics and Gynecology (111601). However, it should not be used long-term or without medical supervision and close monitoring.

PREGNANCY: POSSIBLY UNSAFE
when used orally in excessive doses. There is some concern that high-dose maternal vitamin B6 (pyridoxine) can cause neonatal seizures (4609,6397,8197).

LACTATION: LIKELY SAFE
when used orally in doses not exceeding the recommended dietary allowance (RDA) (3094). The RDA in lactating women is 2 mg daily. There is insufficient reliable information available about the safety of vitamin B6 when used in higher doses in breast-feeding women.

Interactions with Drugs view details

Below is general information about the interactions of the known ingredients contained in the product Cider Vinegar. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

APPLE CIDER VINEGAR (Apple Cider Vinegar powder)

ANTIDIABETES DRUGS

Interaction Rating = Minor Be watchful with this combination.

Severity = Mild • Occurrence = Possible • Level of Evidence = B

Theoretically, taking apple cider vinegar with antidiabetes drugs might increase the risk of hypoglycemia.

Details

Apple cider vinegar might reduce fasting and postprandial blood glucose levels and decrease gastric emptying in people with diabetes (17609,17614,106285,106287). However, not all research agrees (106284). Theoretically, it might have additive effects on glucose levels when used with antidiabetes drugs.

DIGOXIN (Lanoxin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, concomitant use of apple cider vinegar with digoxin might increase the risk of cardiac toxicity.

Details

A case of hypokalemia related to chronic use of apple cider vinegar has been reported (5911). Theoretically, overuse of apple cider vinegar could decrease potassium levels, increasing the risk of toxicity with digoxin.

DIURETIC DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, concomitant use of apple cider vinegar with diuretic drugs might increase the risk of hypokalemia.

Details

A case of hypokalemia related to chronic use of apple cider vinegar has been reported (5911). There is some concern that people taking apple cider vinegar along with potassium depleting diuretics might have an increased risk for hypokalemia.

INSULIN

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, concomitant use of apple cider vinegar with insulin might increase the risk of hypokalemia.

Details

A case of hypokalemia related to chronic use of apple cider vinegar has been reported (5911). Theoretically, overuse of apple cider vinegar concomitantly with insulin might increase the risk of hypokalemia (5911).

CHROMIUM

ANTIDIABETES DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = A

Theoretically, chromium may have additive effects with antidiabetic agents and increase the risk of hypoglycemia.

Details

Some research shows that taking chromium might lower blood glucose levels, especially in patients with poorly controlled type 2 diabetes (7137,14440,15169,94234,95097,95098,98687).

ASPIRIN

Interaction Rating = Minor Be watchful with this combination.

Severity = Insignificant • Occurrence = Possible • Level of Evidence = D

Theoretically, aspirin might increase chromium absorption.

Details

Animal research suggests that aspirin may increase chromium absorption and chromium levels in the blood (21055).

INSULIN

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Theoretically, concomitant use of chromium and insulin might increase the risk of hypoglycemia.

Details

In clinical research, chromium has been shown to increase insulin sensitivity (1952,14440,95095),

LEVOTHYROXINE (Synthroid, others)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Chromium might bind levothyroxine in the intestinal tract and decrease levothyroxine absorption.

Details

Clinical research in healthy volunteers shows that taking chromium picolinate 1000 mcg with levothyroxine 1 mg decreases serum levels of levothyroxine by 17% when compared to taking levothyroxine alone (16012). Advise patients to take levothyroxine at least 30 minutes before or 3-4 hours after taking chromium.

NONSTEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDs)

Interaction Rating = Minor Be watchful with this combination.

Severity = Mild • Occurrence = Possible • Level of Evidence = D

NSAIDs might increase chromium levels in the body.

Details

Drugs that are prostaglandin inhibitors, such as NSAIDs, seem to increase chromium absorption and retention (7135).

GLUCOMANNAN

ORAL DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Theoretically, glucomannan may decrease absorption of drugs taken orally.

Details

Due to its viscosity and bulking effects, there is concern that glucomannan can decrease the absorption of oral drugs. A small clinical study in healthy volunteers shows that taking glyburide 2.5 mg plus glucomannan 3.9 grams with breakfast reduces plasma levels of glyburide when compared with breakfast and glyburide alone (11360). In addition, animal research demonstrates this effect on amoxicillin, but shows increased absorption of metronidazole. This mouse model also demonstrates that metronidazole elimination is prolonged, but amoxicillin elimination is enhanced by 38%; glucomannan may also affect the distribution of some drugs (112703). To avoid changes in absorption, take glucomannan 30-60 minutes after taking oral drugs.

ACEBUTOLOL (Sectral)

Interaction Rating = Minor Be watchful with this combination.

Severity = Insignificant • Occurrence = Possible • Level of Evidence = B

Grapefruit juice can decrease blood levels of acebutolol, potentially decreasing the clinical effects of acebutolol.

Details

Clinical research shows that grapefruit juice can modestly decrease acebutolol levels by 7% and reduce peak plasma concentration by 19% by inhibiting organic anion transporting polypeptide (OATP) (17603,18101). The acebutolol half-life is also extended by 1.1 hours when grapefruit juice is consumed concomitantly (18101). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

ALISKIREN (Tekturna, Rasilez)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Grapefruit juice can decrease blood levels of aliskiren, potentially decreasing the clinical effects of aliskiren.

Details

Clinical research shows that grapefruit juice can decrease aliskiren levels by approximately 60% by inhibiting organic anion transporting polypeptide (OATP) (91428). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

AMIODARONE (Cordarone)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of amiodarone, potentially increasing the effects and adverse effects of amiodarone.

Details

Clinical research shows that grapefruit juice inhibits metabolism and increases absorption of amiodarone. Grapefruit juice increases amiodarone plasma levels by 50% and peak concentration by 84% (17601,17672,22120).

AMPRENAVIR (Agenerase)

Interaction Rating = Minor Be watchful with this combination.

Severity = Mild • Occurrence = Possible • Level of Evidence = B

Grapefruit juice might decrease blood levels of amprenavir, although this is not likely to be clinically significant.

Details

Some clinical research shows that grapefruit juice can slightly decrease amprenavir levels (17673); however, this is probably not clinically significant.

ARTEMETHER (Artenam, Paluther)

Interaction Rating = Major Do not take this combination.

Severity = Moderate • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can increase blood levels of oral artemether, potentially increasing the effects and adverse effects of artemether.

Details

Clinical research shows that grapefruit juice increases the levels of oral artemether by 90% to 250% in healthy males (5065,5066).

BENZODIAZEPINES

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Likely • Level of Evidence = B

Grapefruit juice might increase blood levels of some oral benzodiazepines, potentially increasing the effects and adverse effects of these drugs.

Details

Clinical research shows that grapefruit juice can increase plasma triazolam concentrations. Repeated consumption of grapefruit juice greatly increases triazolam concentrations and prolongs the half-life, probably due to inhibition of cytochrome P450 3A4 (CYP3A4) (7776,22118,22131,22133). Some studies show that grapefruit juice, particularly when taken in large quantities, reduces the clearance and increases the maximum blood levels, area under the plasma concentration curve (AUC), and duration of effect of midazolam. However, there is no effect on intravenous midazolam (4300,10159,11275,17601,22117,22119,16711,91427,95978). Grapefruit juice has also been shown to increase the maximum blood levels and duration of effect of diazepam, but the clinical significance of this is not known (3228). This interaction does not appear to occur with alprazolam (17674).

BLONANSERIN (Lonasen)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of blonanserin, potentially increasing the effects and adverse effects of blonanserin.

Details

Blonanserin is metabolized primarily by cytochrome P450 3A4 (CYP3A4). A small clinical study shows that taking grapefruit juice along with oral blonanserin increases exposure to blonanserin almost 6-fold due to inhibition of intestinal CYP3A4 by grapefruit juice and prolongs the elimination half-life of blonanserin by 2.2-fold due to inhibition of hepatic CYP3A4 by grapefruit juice (96943).

BUDESONIDE (Entocort, UCERIS)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of budesonide, potentially increasing the effects and adverse effects of budesonide.

Details

Budesonide is metabolized by cytochrome P450 3A4 (CYP3A4). A small clinical study shows that taking grapefruit juice along with oral budesonide increases the plasma concentration of budesonide. This effect is attributed to grapefruit-induced inhibition of CYP3A4 in both the colon and small intestine (91425).

BUSPIRONE (BuSpar)

Interaction Rating = Major Do not take this combination.

Severity = Moderate • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can increase blood levels of buspirone, potentially increasing the effects and adverse effects of buspirone.

Details

Clinical research shows that grapefruit juice increases absorption and plasma concentrations of buspirone (3771).

CAFFEINE

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = D

Grapefruit juice can decrease the clearance of caffeine, potentially increasing the effects and adverse effects of caffeine.

Details

Clinical research shows that grapefruit juice decreases caffeine clearance (4300).

CALCIUM CHANNEL BLOCKERS

Interaction Rating = Major Do not take this combination.

Severity = Moderate • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can increase blood levels of oral calcium channel blockers, potentially increasing the effects and adverse effects of these drugs.

Details

Clinical research shows that grapefruit juice increases absorption and plasma concentrations of amlodipine (523), nifedipine (528,22114), nisoldipine (529), verapamil (7779,8285), felodipine, nimodipine, nicardipine, diltiazem, pranidipine, nitrendipine, and manidipine (524,528,1388,4300,7780,11276,22136,53338,22138,22139) (22140,22141,22142,22143,22147,22148,22149,53367,22158), This interaction is likely the result of the inhibition of intestinal metabolism of these drugs by CYP3A4 (7779,7780), although some research suggests grapefruit may alter plasma drug levels by reducing the rate of gastric emptying (22167). Consuming grapefruit juice 1 liter daily increases steady state concentrations of verapamil by as much as 50% (8285). However, some references dispute the clinical relevance of the interactions with amlodipine, diltiazem, and verapamil (3230,4300,22159). Other research in healthy individuals suggests plasma levels of felodipine and nifedipine are not affected when given intravenously (22144,22146). There is considerable interindividual variability in the effect of grapefruit juice on drug metabolism, which might account for inconsistent study results (7777,7779,8285). In healthy older adults, the hemodynamic response to felodipine plus grapefruit juice might be influenced by altered autonomic regulation. In older healthy adults, a single dose of grapefruit juice and felodipine enhanced the blood pressure-lowering effects of felodipine. However, after a week of grapefruit juice and felodipine (steady state), the hypotensive activity was reduced, possibly due to compensatory tachycardia (1392). Research indicates it is necessary to withhold grapefruit juice for as long as 3 days to avoid interactions with felodipine and nisoldipine (5068,5069,6453,22145).

CARBAMAZEPINE (Tegretol)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can increase blood levels of carbamazepine, potentially increasing the effects and adverse effects of carbamazepine.

Details

Clinical research shows that grapefruit juice increases absorption and plasma concentrations of carbamazepine (524).

CARVEDILOL (Coreg)

Interaction Rating = Major Do not take this combination.

Severity = Moderate • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can increase blood levels of carvedilol, potentially increasing the effects and adverse effects of carvedilol.

Details

Clinical research shows that grapefruit juice increases the bioavailability of a single dose of carvedilol by 16% (5071).

CELIPROLOL (Celicard)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can decrease blood levels of celiprolol, potentially decreasing the clinical effects of celiprolol.

Details

In human research, taking grapefruit juice within two hours of celiprolol appears to decrease absorption and blood levels of celiprolol by approximately 85% (91421). This interaction is due to grapefruit-induced inhibition of organic anion transporting polypeptide (OATP) (17603,17604,22161). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

CISAPRIDE (Propulsid)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can increase blood levels of cisapride, potentially increasing the effects and adverse effects of cisapride.

Details

Clinical research shows that grapefruit juice increases the absorption and plasma concentrations of cisapride. According to the cisapride prescribing information, grapefruit juice is contraindicated in patients taking cisapride (1383,3226,17601,22164,22165).

CLOMIPRAMINE (Anafranil)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = D

Theoretically, grapefruit juice might increase blood levels of clomipramine, potentially increasing the effects and adverse effects of clomipramine.

Details

Case reports have shown that clomipramine trough levels increase significantly after the addition of grapefruit juice to the therapeutic regimen (5064).

CLOPIDOGREL (Plavix)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can decrease blood levels of the active metabolite of clopidogrel, thereby decreasing the antiplatelet effect of clopidogrel.

Details

Clopidogrel is an antiplatelet prodrug that is metabolized primarily by cytochrome P450 2C19 (CYP2C19) to form the active metabolite. A small clinical study shows that taking grapefruit juice with clopidogrel decreases plasma levels of the active metabolite by more than 80% and impairs the antiplatelet effect of clopidogrel. This effect is possibly due to grapefruit-induced inhibition of CYP2C19 (91419).

COLCHICINE

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = B

Theoretically, grapefruit juice might increase blood levels of colchicine, potentially increasing the effects and adverse effects of colchicine.

Details

Colchicine is an alkaloid that undergoes P-glycoprotein (P-gp) mediated drug efflux in the intestines, followed by metabolism by cytochrome P450 3A4 (CYP3A4). There is concern that grapefruit juice will increase the effects and adverse effects of colchicine due to grapefruit-induced inhibition of P-gp and/or CYP3A4. In vitro evidence shows that grapefruit juice increases absorption of colchicine by inhibiting P-gp (94158). A case of acute colchicine toxicity has been reported for an 8-year-old female who drank grapefruit juice while taking high-dose colchicine, long-term (94157). However, one small clinical study in healthy adults shows that drinking grapefruit juice 240 mL twice daily for 4 days does not affect the bioavailability or adverse effects of a single dose of colchicine 0.6 mg taken on the fourth day (35762).

CYCLOSPORINE (Neoral, Sandimmune)

Interaction Rating = Major Do not take this combination.

Severity = Moderate • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can increase blood levels of oral cyclosporine, potentially increasing the effects and adverse effects of cyclosporine.

Details

Clinical research shows that grapefruit juice increases the absorption and plasma concentrations of cyclosporine (522,11270,22113,22150,22152,22153,22154,22155). The mechanism of action is unclear. However, there is no effect on intravenous cyclosporine (22151).

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = D

Theoretically, grapefruit juice might increase levels of drugs metabolized by CYP1A2.

Details

In vitro research suggests that grapefruit juice might inhibit CYP1A2 enzymes (12479). So far, this interaction has not been reported in humans.

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Theoretically, grapefruit juice might increase levels of drugs metabolized by CYP2C19.

Details

In vitro research suggests that grapefruit juice might inhibit CYP2C19 enzymes (12479). Also, a small clinical study shows that taking grapefruit juice with clopidogrel, an antiplatelet prodrug that is metabolized primarily by CYP2C19, decreases plasma levels of the active metabolite and impairs the antiplatelet effect of clopidogrel. This effect is likely due to grapefruit-induced inhibition of CYP2C19 (91419).

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = D

Theoretically, grapefruit juice might increase levels of drugs metabolized by CYP2C9.

Details

In vitro research suggests that grapefruit juice might inhibit CYP2C9 enzymes (12479). So far, this interaction has not been reported in humans.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Interaction Rating = Major Do not take this combination.

Severity = Moderate • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can increase levels of drugs metabolized by CYP3A4.

Details

Clinical research shows that grapefruit juice can inhibit CYP3A4 metabolism of drugs, causing increased drug levels and potentially increasing the risk of adverse effects (3227,3774,8283,8285,8286,22129,91427,104190). When taken orally, effects of grapefruit juice on CYP3A4 levels appear to last at least 48 hours (91427). Grapefruit's ability to inhibit CYP3A4 has even been harnessed to intentionally increase levels of venetoclax, which is metabolized by CYP3A4, in an elderly patient with acute myeloid leukemia who could not afford full dose venetoclax. The lower dose of venetoclax in combination with grapefruit juice resulted in serum levels of venetoclax in the therapeutic reference range of full dose venetoclax and positive treatment outcomes for the patient (112287).
Professional consensus recommends the consideration of patient age, existing medical conditions, additional medications, and the potential for additive adverse effects when evaluating the risks of concomitant use of grapefruit juice with any medication metabolized by CYP3A4. While all patients are at risk for interactions with grapefruit juice consumption, patients older than 70 years of age and those taking multiple medications are at the greatest risk for a serious or fatal interaction with grapefruit juice (95970,95972).

DAPOXETINE (Priligy)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of dapoxetine, potentially increasing the effects and adverse effects of dapoxetine.

Details

Pharmacokinetic research shows that drinking grapefruit juice 250 mL prior to taking dapoxetine 60 mg can increase the maximum plasma concentration of dapoxetine by 80% and prolong the elimination half-life by 43%. This effect is attributed to the inhibition of both intestinal and hepatic cytochrome P450 3A4 (CYP3A4) by grapefruit (95975).

DEXTROMETHORPHAN (Robitussin DM, others)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of dextromethorphan, potentially increasing the effects and adverse effects of dextromethorphan.

Details

Clinical research shows that grapefruit juice can inhibit cytochrome P450 3A4 (CYP3A4) metabolism, causing increased dextromethorphan levels (11362).

ERYTHROMYCIN

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of erythromycin, potentially increasing the effects and adverse effects of erythromycin.

Details

Clinical research shows that concomitant use of erythromycin with grapefruit can inhibit cytochrome P450 3A4 (CYP3A4) metabolism of erythromycin, increasing plasma concentrations of erythromycin by 35% (8286).

ESTROGENS

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of estrogens, potentially increasing the effects and adverse effects of estrogens.

Details

Clinical research shows that grapefruit increases the levels of endogenous and exogenous estrogens by inhibiting cytochrome P450 3A4 (CYP3A4) enzymes (525,526,14858). Grapefruit juice increases exogenously administered 17-beta-estradiol by about 20% in females without ovaries and ethinyl-estradiol in healthy females (525,526,22160).

ETOPOSIDE (VePesid)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can decrease blood levels of etoposide, potentially decreasing the clinical effects of etoposide.

Details

Clinical research shows that grapefruit juice decreases the absorption and plasma concentrations of etoposide. There is some evidence that grapefruit juice co-administered with oral etoposide can reduce levels of etoposide by about 26% (8744). Grapefruit juice seems to inhibit organic anion transporting polypeptide (OATP), which is a drug transporter in the gut, liver, and kidney (7046,17603,17604). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

FEXOFENADINE (Allegra)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Mild • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can decrease blood levels of fexofenadine, thereby decreasing the clinical effects of fexofenadine.

Details

Clinical research shows that grapefruit juice can significantly decrease oral absorption and blood levels of fexofenadine. In one study, consuming a drink containing grapefruit juice 25% decreased bioavailability of fexofenadine by about 24%. Consuming a full-strength grapefruit juice drink reduced bioavailability by 67% (7046). In another study, consuming grapefruit juice 300 mL decreased fexofenadine levels by 42%. Consuming 1200 mL of grapefruit juice reduced levels by 64% (17602). Similarly, drinking grapefruit juice 240 mL decreased the oral bioavailability of fexofenadine by 25% in another pharmacokinetic study (112288). Fexofenadine manufacturer data indicates that concomitant administration of grapefruit juice and fexofenadine results in larger wheal and flare sizes in research models. This suggests that grapefruit also reduces the clinical response to fexofenadine (17603).
Grapefruit juice seems to inhibit organic anion transporting polypeptide (OATP), which is a drug transporter in the gut, liver, and kidney (7046,17603,17604,22161). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

FLUVOXAMINE (Luvox)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Grapefruit juice can increase blood levels of fluvoxamine, potentially increasing the effects and adverse effects of fluvoxamine.

Details

Clinical research shows that grapefruit juice inhibits metabolism and increases fluvoxamine levels and peak concentration (17675).

HALOFANTRINE

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of halofantrine, potentially increasing the effects and adverse effects of halofantrine.

Details

Clinical research shows that grapefruit juice inhibits cytochrome P450 3A4 (CYP3A4) metabolism, which increases halofantrine levels and peak concentration, as well as a marker of ventricular tachyarrhythmia potential (22129).

HMG-CoA REDUCTASE INHIBITORS ("Statins")

Interaction Rating = Major Do not take this combination.

Severity = Moderate • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can increase blood levels of statins that are metabolized by cytochrome P450 3A4 (CYP3A4), potentially increasing the effects and adverse effects of these statins. Additionally, grapefruit juice might interfere with the bioavailability of statins that are substrates of organic anion transporting polypeptides (OATP).

Details

Clinical research shows that grapefruit juice inhibits metabolism and increases absorption and plasma concentrations of statins that are metabolized by CYP3A4. These include lovastatin (527,11274), simvastatin (3774,7782,22127), and atorvastatin (3227,12179,22126). Keep in mind that there is considerable variability in the effect of grapefruit juice on drug metabolism, so individual patient response is difficult to predict (7777,7781).
Some statins, including pravastatin, fluvastatin, pitavastatin, and rosuvastatin, are not metabolized by CYP3A4. However, grapefruit juice might still affect the bioavailability of these statins. These statins are substrates of OATP. Grapefruit juice can inhibit OATP. Therefore, grapefruit juice may reduce the bioavailability or increase drug levels of these statins depending on the type of OATP. However, grapefruit juice affects OATP for only a short time. Therefore, separating drug administration by at least 4 hours is likely to avoid this interaction (3227,12179,17601,22126,91420).

ITRACONAZOLE (Sporanox)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Grapefruit juice can interfere with itraconazole absorption, although the clinical significance of this interaction is unclear.

Details

Clinical research shows that grapefruit juice can affect itraconazole absorption and might increase or decrease itraconazole levels (310,17601,22123).

LEVOTHYROXINE (Synthroid, others)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Grapefruit juice can decrease blood levels of levothyroxine, potentially decreasing the effectiveness of levothyroxine.

Details

Clinical research shows that grapefruit juice modestly decreases levothyroxine levels by 11% by inhibiting organic anion transporting polypeptide (OATP) (17604,22163). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

LOSARTAN (Cozaar)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can decrease blood levels of the active metabolite of losartan, potentially decreasing the clinical effects of losartan.

Details

Losartan is an inactive prodrug which must be metabolized to its active form, E-3174, to be effective. In one human study, grapefruit juice reduced losartan metabolism, increased losartan AUC, and reduced the AUC of the major active losartan metabolite, E-3174 (1391).

METHADONE (Dolophine)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of methadone, potentially increasing the effects and adverse effects of methadone.

Details

Clinical research shows that grapefruit juice inhibits the metabolism of methadone, increasing methadone levels and peak concentrations (17676). In one case, a 51-year-old male taking methadone 90 mg daily and no other medications was found unresponsive. The patient reported drinking grapefruit juice 500 mL daily for 3 days prior to the event. Methadone is a substrate of cytochrome P450 3A4 (CYP3A4), and grapefruit juice-induced inhibition of CYP3A4 is the likely cause of this interaction (102056).

METHYLPREDNISOLONE

Interaction Rating = Major Do not take this combination.

Severity = Moderate • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can increase blood levels of methylprednisolone, potentially increasing the effects and adverse effects of methylprednisolone.

Details

Clinical research shows that grapefruit juice can increase the plasma concentration of orally administered methylprednisolone. Grapefruit juice 200 mL three times daily given with methylprednisolone 16 mg increased methylprednisolone half-life by 35%, peak plasma concentration by 27%, and total area under the curve by 75% (3123).

NADOLOL (Corgard)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Grapefruit juice might decrease blood levels of nadolol, potentially decreasing the clinical effects of nadolol.

Details

Nadolol is a substrate of organic anion transporting polypeptide 1A2 (OATP1A2) (17603,17604,22161). Some research shows that grapefruit juice and its constituent naringin can inhibit organic anion transporting polypeptides (OATP), which can reduce the bioavailability of OATP substrates (17603,17604,22161,91427). However, preliminary clinical research shows that grapefruit juice containing a low amount of naringin does not significantly affect levels of nadolol (91422). It is not known if grapefruit juice containing higher amounts of naringin reduces the bioavailability of nadolol.

NILOTINIB (Tasigna)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of nilotinib, potentially increasing the effects and adverse effects of nilotinib.

Details

Clinical research shows that grapefruit juice inhibits metabolism and increases absorption of nilotinib. Grapefruit juice increases nilotinib levels by 29% and peak concentration by 60% (17677).

ORGANIC ANION-TRANSPORTING POLYPEPTIDE SUBSTRATES (OATP)

Interaction Rating = Major Do not take this combination.

Severity = Moderate • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can decrease levels of drugs that are substrates of OATP.

Details

In vitro and clinical research show that consuming grapefruit juice inhibits OATP, which reduces the bioavailability of oral drugs that are substrates of OATP. Various clinical studies have shown reduced absorption of OATP substrates when taken with grapefruit, including fexofenadine, acebutolol, aliskiren, celiprolol, levothyroxine, nadolol, and pitavastatin (17603,17604,18101,22126,22134,22161,22163,91420,91427,91428,112288). Grapefruit juice is thought to affect OATP for only a short time. Therefore, separating drug administration and consumption of grapefruit by at least 4 hours is likely to prevent this interaction (17603,17604).

OXYCODONE (Oxycontin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Mild • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of oxycodone, potentially increasing the effects and adverse effects of oxycodone.

Details

Oxycodone is metabolized by both cytochrome P450 3A4 (CYP3A4) and cytochrome P450 2D6 (CYP2D6). A small clinical study shows that grapefruit juice can increase plasma levels of oral oxycodone about 1.7-fold by inhibiting CYP3A4. While the analgesic effects of oxycodone do not seem to be affected, taking grapefruit juice along with oxycodone may theoretically increase the adverse effects of oxycodone (91423).

P-GLYCOPROTEIN SUBSTRATES

Interaction Rating = Minor Be watchful with this combination.

Severity = Mild • Occurrence = Possible • Level of Evidence = B

Grapefruit juice does not seem to affect renal P-glycoprotein (P-gp). Theoretically, it might inhibit intestinal P-gp, but evidence is conflicting.

Details

While most in vitro research shows that grapefruit products inhibit P-gp, (1390,11270,11278,11362,95976), research in humans is less clear. Two small clinical studies in healthy adults using digoxin as a probe substrate show that grapefruit juice does not inhibit P-gp in the kidneys (11277,11282). It is unclear whether this applies to intestinal P-gp, for which digoxin is not considered to be a sensitive probe (105568). Grapefruit juice has been shown to reduce levels of fexofenadine (7046,17602,112288), and increase levels of quinidine (5067,22121). However, as both of these drugs are also substrates of other enzymes and transporters, it is unclear what role, if any, intestinal P-gp has in these findings.

PITAVASTATIN (Livalo)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Mild • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can increase blood levels of pitavastatin, potentially increasing the effects and adverse effects of pitavastatin.

Details

Pharmacokinetic research shows that taking grapefruit juice with pitavastatin 2-4 mg can increase blood levels of pitavastatin by 13% to 14%. Unlike simvastatin and atorvastatin, pitavastatin is not significantly metabolized by cytochrome P450 3A4 (CYP3A4) enzymes. Grapefruit juice appears to increase levels of pitavastatin by inhibiting its uptake by organic anion transporting polypeptide 1B1 (OATP1B1) into hepatocytes for metabolism and clearance from the body (22126,91420). Grapefruit juice seems to increase levels of pitavastatin to a greater degree in patients homozygous for a specific polymorphism (388A>G) in the OATP1B1 gene compared to those heterozygous for this polymorphism (91420).

PRASUGREL (Effient)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can decrease blood levels of the active metabolite of prasugrel, thereby decreasing the antiplatelet effect of prasugrel.

Details

Prasugrel is a prodrug that is metabolized by cytochrome P450 3A4 (CYP3A4) into its active metabolite. A small pharmacokinetic study in healthy volunteers shows that drinking grapefruit juice 200 mL three times daily for 4 days and taking a single dose of prasugrel 10 mg with an additional 200 mL of grapefruit juice on day 3, results in a 49% lower peak plasma level and a 26% lower overall plasma exposure to the active metabolite when compared with drinking water. However, despite the reduced exposure, platelet aggregation seems to be reduced by an average of only 5% (105567). The clinical significance of this interaction is unclear.

PRAZIQUANTEL (Biltricide)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of praziquantel, potentially increasing the effects and adverse effects of praziquantel.

Details

Clinical research shows that grapefruit juice can inhibit cytochrome P450 3A4 (CYP3A4) metabolism of praziquantel. Plasma concentrations of praziquantel can increase by as much as 160% when administered with 250 mL of commercially available grapefruit juice (8282).

PRIMAQUINE

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Grapefruit juice may increase blood levels of primaquine, potentially increasing the effects and adverse effects of primaquine.

Details

Clinical research shows that grapefruit juice increases the bioavailability of primaquine by approximately 20% (22130). The clinical significance of this interaction is not clear.

QT INTERVAL-PROLONGING DRUGS

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit or grapefruit juice, especially if consumed in large amounts, can cause additive QT interval prolongation when taken with QT interval-prolonging drugs, potentially increasing the risk of ventricular arrhythmias.

Details

Clinical research in healthy volunteers shows that drinking 6 liters of grapefruit juice over 6 hours prolonged the QTc by a peak amount of 14 milliseconds (ms). This prolongation was similar to the QT prolongation caused by the drug moxifloxacin. In individuals with long QT syndrome, a smaller dose of grapefruit juice, 1.5 liters, resulted in a greater peak QTc prolongation of about 30 ms (100249). The effect of smaller quantities of grapefruit juice on the QT interval is unclear.

QUETIAPINE (Seroquel)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice may increase blood levels of quetiapine, increasing the effects and adverse effects of quetiapine.

Details

Quetiapine is metabolized by cytochrome P450 3A4 (CYP3A4). Grapefruit can inhibit CYP3A4 (3227,3774,8283,8285,8286,22129,91427,104190). In one case report, a healthy 28-year-old female with bipolar disorder stabilized on quetiapine 800 mg daily presented with quetiapine toxicity considered to be related to consuming a gallon of grapefruit juice over the past 24 hours (108848).

QUINIDINE

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can alter blood levels of quinidine, potentially increasing or decreasing the clinical effects of quinidine.

Details

Clinical research shows that grapefruit juice decreases quinidine absorption, clearance, and metabolism, and prolongs the half-life by about 20% (5067,22121).

SAQUINAVIR (Fortovase, Invirase)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of saquinavir, potentially increasing the effects and adverse effects of saquinavir.

Details

Clinical research shows that grapefruit juice increases the absorption and plasma concentrations of saquinavir (3773,22132).

SCOPOLAMINE (Transderm Scop)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of scopolamine, potentially increasing the effects and adverse effects of scopolamine.

Details

Clinical research shows that grapefruit juice can inhibit cytochrome P450 3A4 (CYP3A4) metabolism of scopolamine, increasing its absorption and plasma concentrations. Oral bioavailability of scopolamine can increase by 30% when administered with 150 mL of grapefruit juice (8284).

SERTRALINE (Zoloft)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Grapefruit juice can increase blood levels of sertraline, potentially increasing the effects and adverse effects of sertraline.

Details

Clinical research shows that grapefruit juice inhibits the cytochrome P450 3A4 (CYP3A4) metabolism of sertraline, increasing blood levels of sertraline (22122).

SILDENAFIL (Viagra)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of sildenafil, potentially increasing the effects and adverse effects of sildenafil.

Details

Clinical research shows that grapefruit juice inhibits cytochrome P450 3A4 (CYP3A4) metabolism of sildenafil, increasing its absorption and plasma concentrations. Oral bioavailability of sildenafil can increase by 23% when administered with 500 mL of commercially available grapefruit juice (8283).

SUNITINIB (Sutent)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Unlikely • Level of Evidence = B

Grapefruit juice may slightly increase blood levels of sunitinib, potentially increasing the effects and adverse effects of sunitinib.

Details

Sunitinib is metabolized by cytochrome P450 3A4 (CYP3A4). Grapefruit and grapefruit juice can inhibit CYP3A4 and increase levels of some drugs metabolized by this enzyme. One small clinical study shows that drinking 200 mL of grapefruit juice three times daily can increase the bioavailability of sunitinib by 11% (91429). While this effect is unlikely to be clinically significant, patients should use caution when using grapefruit along with sunitinib. Dose adjustments may be necessary.

TACROLIMUS (Prograf)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Likely • Level of Evidence = B

Grapefruit juice can increase blood levels of tacrolimus, potentially increasing the effects and adverse effects of tacrolimus.

Details

Clinical research shows that drinking grapefruit juice 200 mL daily while taking tacrolimus 3 mg daily increases the trough blood concentration of tacrolimus by approximately 3-fold in patients with connective tissue diseases (95974). A single case has also reported a 10-fold increase in tacrolimus trough levels after the ingestion of grapefruit juice over 3 days (22122). This effect is attributed to the inhibition of cytochrome P450 3A4 (CYP3A4) by grapefruit (95974).

TADALAFIL (Cialis)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, grapefruit juice might increase blood levels of tadalafil, potentially increasing the effects and adverse effects of tadalafil.

Details

Animal research shows that grapefruit juice increases tadalafil serum concentrations and overall exposure, likely through inhibition of cytochrome P450 3A4 enzymes (104189).

TALINOLOL

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Grapefruit juice might decrease blood levels of talinolol, potentially decreasing the clinical effects of talinolol.

Details

Clinical research suggests that grapefruit juice reduces talinolol bioavailability, likely by inhibiting intestinal uptake (22135). The clinical significance of this effect is unclear.

TERFENADINE (Seldane)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of terfenadine, potentially increasing the effects and adverse effects of terfenadine.

Details

Clinical research shows that grapefruit juice increases the absorption and plasma concentrations of terfenadine (530,22124,22125). The mechanism of action is unclear.

THEOPHYLLINE

Interaction Rating = Moderate Be cautious with this combination.

Severity = Mild • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can decrease blood levels of theophylline, potentially decreasing the effectiveness of theophylline.

Details

Clinical research shows that grapefruit juice seems to modestly decrease theophylline levels when given concurrently with sustained-release theophylline (11013). The mechanism of this interaction is unknown.

TICAGRELOR (Brilinta)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of ticagrelor, thereby increasing the effects and adverse effects of ticagrelor.

Details

Ticagrelor is metabolized by cytochrome P450 3A4 (CYP3A4). Grapefruit can inhibit CYP3A4. A small clinical study shows that taking grapefruit juice with ticagrelor increases blood levels of ticagrelor more than two-fold and increases the antiplatelet activity of ticagrelor (91418).

TOLVAPTAN (Samsca)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Grapefruit juice can increase blood levels of tolvaptan, potentially increasing the effects and adverse effects of tolvaptan.

Details

Tolvaptan is metabolized by cytochrome P450 3A4 (CYP3A4). Grapefruit can inhibit CYP3A4. A small clinical study shows that grapefruit juice can increase the bioavailability and blood levels of tolvaptan by approximately 1.6-fold for up to 16 hours (91426).

WARFARIN (Coumadin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, drinking large amounts of grapefruit juice might increase the effects and adverse effects of warfarin.

Details

In one case report, a patient experienced significantly increased international normalized ratio (INR) associated with consumption of 50 ounces of grapefruit juice daily (12061). However, smaller amounts of grapefruit juice might not be a problem. In a small clinical trial, consumption of 24 ounces of grapefruit juice daily for one week had no effect on INR in males treated with warfarin (12063).

ACE INHIBITORS (ACEIs)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = D

Theoretically, laminaria might increase the risk of hyperkalemia when taken with ACEIs.

Details

Laminaria contains potassium (19).

AMIODARONE (Cordarone)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = D

Theoretically, combining laminaria with amiodarone might cause excessively high iodine levels.

Details

Amiodarone contains 37.3% iodine and can increase iodine levels. Concomitant use with laminaria supplements, some of which may contain as much as 1000 mcg iodine, might increase the risk of adverse effects from iodine, including altered thyroid function (9556,94046).

ANTITHYROID DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = D

Due to its iodine content, laminaria might alter the effects of antithyroid drugs.

Details

Some laminaria supplements contain up to 1000 mcg of iodine (9556,94046). Iodine in high doses has been reported to cause both hyperthyroidism and hypothyroidism, depending on the individual's past medical history. Taking laminaria could theoretically alter the effects of antithyroid drugs.

DIGOXIN (Lanoxin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, laminaria might increase the risk of hyperkalemia, which could increase the effects and adverse effects of digoxin.

Details

Laminaria contains potassium (19).

POTASSIUM-SPARING DIURETICS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = D

Theoretically, laminaria might increase the risk of hyperkalemia when taken with potassium-sparing diuretics.

Details

Laminaria contains potassium (19).

THYROID HORMONE

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = D

Due to its iodine content, laminaria might alter the effects of thyroid hormone.

Details

None known.

VITAMIN B6

AMIODARONE (Cordarone)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Theoretically, vitamin B6 might increase the photosensitivity caused by amiodarone.

Details

Despite initial case reports suggesting that pyridoxine may have a protective effect against amiodarone-induced photosensitivity, preliminary clinical research suggests that pyridoxine may actually exacerbate this adverse effect (8892,8893).

ANTIHYPERTENSIVE DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Theoretically, vitamin B6 may have additive effects when used with antihypertensive drugs.

Details

Research in hypertensive rats shows that vitamin B6 can decrease systolic blood pressure (30859,82959,83093). Similarly, clinical research in patients with hypertension shows that taking high doses of vitamin B6 may reduce systolic and diastolic blood pressure, possibly by reducing plasma levels of epinephrine and norepinephrine (83091).

LEVODOPA

Interaction Rating = Minor Be watchful with this combination.

Severity = Moderate • Occurrence = Unlikely • Level of Evidence = D

Vitamin B6 may increase the metabolism of levodopa when taken alone, but not when taken in conjunction with carbidopa.

Details

Vitamin B6 (pyridoxine) enhances the metabolism of levodopa, reducing its clinical effects. However, this interaction does not occur when carbidopa is used concurrently with levodopa (Sinemet). Therefore, it is not likely to be a problem in most people (3046).

PHENOBARBITAL (Luminal)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

High doses of vitamin B6 may reduce the levels and clinical effects of phenobarbital.

Details

Preliminary clinical evidence suggests that vitamin B6 200 mg daily can reduce plasma levels of phenobarbital, possibly by increasing metabolism. It is not known whether lower doses have any effect. Advise people taking phenobarbital to avoid high doses of vitamin B6 (3046,10801).

PHENYTOIN (Dilantin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

High doses of vitamin B6 may reduce the levels and clinical effects of phenytoin.

Details

Preliminary clinical evidence suggests that vitamin B6 200 mg daily can reduce plasma levels of phenytoin, possibly by increasing metabolism. It is not known whether lower doses have any effect. Advise people taking phenytoin to avoid high doses of vitamin B6 (3046,10801).

Report an Adverse Reaction to Cider Vinegar

Adverse Effects view details

Below is general information about the adverse effects of the known ingredients contained in the product Cider Vinegar. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

APPLE CIDER VINEGAR (Apple Cider Vinegar powder)

General ...In food amounts, apple cider vinegar is well tolerated. It seems to be well tolerated when used orally, short-term for medicinal purposes. However, in larger amounts, long-term use may be unsafe.
Topically, apple cider vinegar may be unsafe.
Serious Adverse Effects (Rare):
Orally: Hypokalemia, hyperreninemia, and osteoporosis have been reported with long-term use.
Topically: Chemical burns, skin irritation.

Dermatologic ...Topically, apple cider vinegar may cause chemical burns. There is one published report of an individual who developed a chemical burn caused by a single topical application of apple cider vinegar containing 5% acetic acid to the skin (91662). Another case of chemical burn has been reported for a 14-year-old patient who applied apple cider vinegar to the skin for 3 days to remove a nevi. Symptoms included erythema, irritation, and non-inflammatory skin erosion. Symptoms were treated by applying mupirocin 2% ointment twice a day for several weeks and using sunscreen on the erosion and surrounding skin (93074). In one clinical trial, use of 0.5% apple cider vinegar soaks commonly caused skin irritation. One patient in this study experienced a nonpruritic papular rash, while another patient experienced severe pruritis with burning and erosion (101172). In another report, a female had an apple cider vinegar tablet lodged in the throat for 30 minutes, resulting in tenderness and pain in the larynx and difficulty swallowing for 6 months following the incident. This was thought to be due to the acid content of the tablet (13183).

Renal ...There is one published report of an individual who developed hypokalemia, elevated renin levels, high positive urinary anion gap, and osteoporosis after ingesting apple cider vinegar 250 mL per day for 6 years. The osteoporosis was attributed to buffering of the acute acid load by bone, and the other effects were attributed to significant bicarbonate excretion (31730).

CHROMIUM

General ...Orally, chromium is generally well tolerated.
Most Common Adverse Effects:
Orally: Gastrointestinal irritation, headaches, insomnia, irritability, mood changes.
Serious Adverse Effects (Rare):
Orally: Rare cases of kidney and liver damage, rhabdomyolysis, and thrombocytopenia have been reported.

Dermatologic ...Orally, chromium-containing supplements may cause acute generalized exanthematous pustulosis (42561), skin rashes (42679), and urticaria (17224). Also, chromium picolinate or chromium chloride may cause systemic contact dermatitis when taken orally, especially in patients with contact allergy to chromium (6624,90058). In one clinical study, a patient taking chromium nicotinate 50 mcg daily reported itchy palms that improved after the intervention was discontinued. It is unclear of this effect was due to the chromium or another factor (95096).
Topically, hexavalent chromium, which can be present in some cement, leather products, or contaminated soil, may cause allergic contact dermatitis (42645,42789,90060,90064,110606).
A case of lichen planus has been reported for a patient following long-term occupational exposure to chromium (42688).

Endocrine ...Orally, cases of hypoglycemia have been reported for patients taking chromium picolinate 200-1000 mcg daily alone or 200-300 mcg two or three times weekly in combination with insulin (42672,42783). Chromium picolinate has also been associated with weight gain in young females who do not exercise and in those following a weight-lifting program (1938).

Gastrointestinal ...Orally, chromium in the form of chromium picolinate, chromium polynicotinate, chromium-containing brewer's yeast, or chromium-containing milk powder may cause nausea, vomiting, diarrhea, decreased appetite, constipation, flatulence, or gastrointestinal upset (14325,42594,42607,42622,42643,42679).
Long-term exposure to heavy metals, including chromium, has been associated with increased risk of gallbladder disease and cancer (42682,42704).

Genitourinary ...Orally, chromium polynicotinate has been associated with disrupted menstrual cycles in patients taking the supplement to prevent weight gain during smoking cessation (42643).

Hematologic ...Anemia, hemolysis, and thrombocytopenia were reported in a 33 year-old female taking chromium picolinate 1200-2400 mcg daily for 4-5 months (554). The patient received supportive care, blood product transfusions, and hemodialysis and was stabilized and discharged a few days later. Lab values were normal at a one-year follow-up.

Hepatic ...Liver damage has been reported for a 33-year-old female taking chromium picolinate 1200 mcg daily for 4-5 months (554). Also, acute hepatitis has been reported in a patient taking chromium polynicotinate 200 mcg daily for 5 months (9141). Symptoms resolved when the product was discontinued. Two cases of hepatotoxicity have been reported in patients who took a specific combination product (Hydroxycut), which also contained chromium polynicotinate in addition to several herbs (13037).

Musculoskeletal ...Acute rhabdomyolysis has been reported for a previously healthy 24-year-old female who ingested chromium picolinate 1200 mcg over a 48-hour time period (42786). Also, chromium polynicotinate has been associated with leg pain and paresthesia in patients taking the supplement to prevent weight gain during smoking cessation (42643).

Neurologic/CNS ...Orally, chromium picolinate may cause headache, paresthesia, insomnia, dizziness, and vertigo (6860,10309,14325,42594). Vague cognitive symptoms, slowed thought processes, and difficulty driving occurred on three separate occasions in a healthy 35-year-old male after oral intake of chromium picolinate 200-400 mcg (42751). Transient increases in dreaming have been reported in three patients with dysthymia treated with chromium picolinate in combination with sertraline (2659). A specific combination product (Hydroxycut) containing chromium, caffeine, and ephedra has been associated with seizures (10307). But the most likely causative agent in this case is ephedra.

Psychiatric ...Orally, chromium picolinate has been associated with irritability and mood changes in patients taking the supplement to lose weight, while chromium polynicotinate has been associated with agitation and mood changes in patients taking the supplement to prevent weight gain during smoking cessation (6860,42643).

Renal ...Orally, chromium picolinate has been associated with at least one report of chronic interstitial nephritis and two reports of acute tubular necrosis (554,1951,14312). Laboratory evidence suggests that chromium does not cause kidney tissue damage even after long-term, high-dose exposure (7135); however, patient- or product-specific factors could potentially increase the risk of chromium-related kidney damage. More evidence is needed to determine what role, if any, chromium has in potentially causing kidney damage.
Intravenously, chromium is associated with decreased glomerular filtration rate (GFR) in children who receive long-term chromium-containing total parenteral nutrition - TPN (11787). Topically, burns caused by chromic acid, a hexavalent form of chromium, have been associated with acute chromium poisoning with acute renal failure (42699). Early excision of affected skin and dialysis are performed to prevent systemic toxicity.

Other ...Another form of chromium, called hexavalent chromium, is unsafe. This type of chromium is a by-product of some manufacturing processes. Chronic exposure can cause liver, kidney, or cardiac failure, pulmonary complications, anemia, and hemolysis (9141,11786,42572,42573,42699). Occupational inhalation of hexavalent chromium can cause ulceration of the nasal mucosa and perforation of the nasal septum, and has been associated with pneumoconiosis, allergic asthma, cough, shortness of breath, wheezing, and increased susceptibility to respiratory tract cancer and even stomach and germ cell cancers (42572,42573,42601,42610,42636,42667,42648,42601,42788,90056,90066). Although rare, cases of interstitial pneumonia associated with chromium inhalation have been reported. Symptoms resolved with corticosteroid treatment (42614).

GLUCOMANNAN

General ...Orally, glucomannan is generally well tolerated when taken with plenty of water or other liquid.
Most Common Adverse Effects:
Orally: Abdominal pain, bloating, constipation, diarrhea, flatulence, nausea, and vomiting.
Serious Adverse Effects (Rare):
Orally: Choking and esophageal or gastrointestinal obstruction, especially when taken as a dry powder or in tablet form.

Gastrointestinal ...Orally, glucomannan can cause gastrointestinal disturbances, including abdominal pain, bloating, constipation, diarrhea, flatulence, nausea, and vomiting, especially when taken in doses of more than 3 grams daily (57781,57784,92004,92010,92011,97935,106411). Esophageal and gastrointestinal obstructions have been reported when dry glucomannan-containing products are taken with insufficient fluid (11293,57785,106410).

Hepatic ...Acute cholestatic hepatitis occurred in a 31-year-old male after taking glucomannan orally for 45 days (57777). He was also taking other supplements, including garlic and chitosan, so it is unclear whether the hepatitis was due to glucomannan, other supplements, or the combination.

Pulmonary/Respiratory ...Cases of occupational respiratory disorders, including respiratory sensitization and bronchial asthma, have been reported in workers exposed to glucomannan (57789,57810).

General ...Orally, grapefruit and grapefruit juice are generally well tolerated.
Serious Adverse Effects (Rare):
Orally: Allergic reactions in sensitive individuals have been reported. When large quantities are consumed, arrhythmias, mineralocorticoid excess, QT prolongation, and pseudohyperaldosteronism have been reported. There is also some concern for increased breast cancer risk with grapefruit consumption.

Cardiovascular ...Orally, consumption of pink grapefruit juice 1000 mL can cause QT prolongation and cause arrhythmias in healthy patients and worsen arrhythmias in cardiomyopathy patients (13031,91424).

Endocrine ...Orally, high doses of grapefruit juice have been observed to cause pseudohyperaldosteronism and mineralocorticoid excess (53340,53346).

Gastrointestinal ...In a case report, grapefruit juice held against the teeth resulted in enamel and tooth surface loss (53368).

Immunologic ...Orally, grapefruit can cause allergic sensitization characterized by eosinophilic gastroenteritis, urticaria, and generalized pruritus (53351,53360).

Oncologic ...Preliminary population research shows that postmenopausal adults who consume a quarter or more of a whole grapefruit daily have a 25% to 30% increased risk of developing breast cancer (14858). Grapefruit is a potent inhibitor of cytochrome P450 3A4, which metabolizes estrogen. Consuming large amounts of grapefruit might significantly increase endogenous estrogen levels and therefore increase the risk of breast cancer. More evidence is needed to validate these findings. Until more is known, advise patients to consume grapefruit in moderation.

Renal ...In population research, consumption of 240 mL/day of grapefruit juice is associated with an increased risk of kidney stones (4216,53372).

General ...Orally, iodine-reduced laminaria seems to be well tolerated, while other laminaria formulations may contain excess amounts of iodine, as well as arsenic.
Most Common Adverse Effects:
Intravaginally: Cervical bleeding and pelvic cramps.
Serious Adverse Effects (Rare):
Orally: Arsenic poisoning.
Intravaginally: Rupture of cervical wall, fetal hypoxia, and fetal death. Anaphylaxis in sensitive individuals.

Dermatologic ...Orally, laminaria has been linked to a report of induced or exacerbated acne (9555).

Endocrine ...Orally, laminaria can affect levels of certain thyroid hormones, and might cause hypothyroidism or hyperthyroidism, or exacerbate existing hyperthyroidism (9556,94046).

Genitourinary ...Intravaginally, laminaria used for cervical ripening can cause pelvic cramps and cervical bleeding (8945). Uterine contractions associated with laminaria use have been implicated in fetal hypoxia and subsequent intrauterine death (6). Use of endocervical laminaria tents has been associated with possible rupture of the cervical wall and subsequent neonatal and parental infection (6,8945).

Immunologic ...There are case reports of anaphylactic reactions to laminaria when used intravaginally as a cervical dilator. In at least one case, ventilation was required (102766).

Other ...Laminaria concentrates arsenic from the ocean. In one case, use of an oral laminaria supplement for several months resulted in symptoms of arsenic poisoning including headache, weakness, fatigue, worsening memory loss, rash, nail damage, diarrhea, and vomiting. Urinary arsenic levels were elevated (15588). The concentration of arsenic in laminaria may vary between different batches, and also depends upon the part of the world where it was harvested (645,10275,15588). The concentration of arsenic has been reported to be higher in preparations from Australia than from Great Britain (645,10275).

General ...Orally, lecithin is well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, diarrhea, fullness, and nausea.

Dermatologic ...Orally, lecithin can cause allergic skin reactions in people with egg or soy allergies (15705).

Gastrointestinal ...Orally, lecithin may cause abdominal pain, diarrhea, fullness, and nausea (5140,6243,14817,14822,14838,19204,59281).

Neurologic/CNS ...Orally, lecithin caused CNS complaints and agitation in one patient in a clinical trial (59261).

VITAMIN B6

General ...Orally or by injection, vitamin B6 is well tolerated in doses less than 100 mg daily.
Most Common Adverse Effects:
Orally or by injection: Abdominal pain, allergic reactions, headache, heartburn, loss of appetite, nausea, somnolence, vomiting.
Serious Adverse Effects (Rare):
Orally or by injection: Sensory neuropathy (high doses).

Dermatologic ...Orally, vitamin B6 (pyridoxine) has been linked to reports of skin and other allergic reactions and photosensitivity (8195,9479,90375). High-dose vitamin B6 (80 mg daily as pyridoxine) and vitamin B12 (20 mcg daily) have been associated with cases of rosacea fulminans characterized by intense erythema with nodules, papules, and pustules. Symptoms may persist for up to 4 months after the supplement is stopped, and may require treatment with systemic corticosteroids and topical therapy (10998).

Gastrointestinal ...Orally or by injection, vitamin B6 (pyridoxine) can cause nausea, vomiting, heartburn, abdominal pain, mild diarrhea, and loss of appetite (8195,9479,16306,83064,83103,107124,107127,107135). In a clinical trial, one patient experienced infectious gastroenteritis that was deemed possibly related to taking vitamin B6 (pyridoxine) orally up to 20 mg/kg daily (90796). One small case-control study has raised concern that long-term dietary vitamin B6 intake in amounts ranging from 3.56-6.59 mg daily can increase the risk of ulcerative colitis (3350).

Hematologic ...Orally or by injection, vitamin B6 (pyridoxine) can cause decreased serum folic acid concentrations (8195,9479). One case of persistent bleeding of unknown origin has been reported in a clinical trial for a patient who used vitamin B6 (pyridoxine) 100 mg twice daily on days 16 to 35 of the menstrual cycle (83103). It is unclear if this effect was due to vitamin B6 intake.

Musculoskeletal ...Orally or by injection, vitamin B6 (pyridoxine) can cause breast soreness or enlargement (8195).

Neurologic/CNS ...Orally or by injection, vitamin B6 (pyridoxine) can cause headache, paresthesia, and somnolence (8195,9479,16306). Vitamin B6 (pyridoxine) can also cause sensory neuropathy, which is related to daily dose and duration of intake. Doses exceeding 1000 mg daily or total doses of 1000 grams or more pose the most risk, although neuropathy can occur with lower daily or total doses as well (8195). The mechanism of the neurotoxicity is unknown, but is thought to occur when the liver's capacity to phosphorylate pyridoxine via the active coenzyme pyridoxal phosphate is exceeded (8204). Some researchers recommend taking vitamin B6 as pyridoxal phosphate to avoid pyridoxine neuropathy, but its safety is unknown (8204). Vitamin B6 (pyridoxine) neuropathy is characterized by numbness and impairment of the sense of position and vibration of the distal limbs, and a gradual progressive sensory ataxia (8196,10439). The syndrome is usually reversible with discontinuation of pyridoxine at the first appearance of neurologic symptoms. Residual symptoms have been reported in patients taking more than 2 grams daily for extended periods (8195,8196). Tell patients daily doses of 100 mg or less are unlikely to cause problems (3094).

Oncologic ...In females, population research has found that a median intake of vitamin B6 1. 63 mg daily is associated with a 3.6-fold increased risk of rectal cancer when compared with a median intake of 1.05 mg daily (83024). A post-hoc subgroup analysis of results from clinical research in adults with a history of recent stroke or ischemic attack suggests that taking folic acid, vitamin B12, and vitamin B6 does not increase cancer risk overall, although it was associated with an increased risk of cancer in patients who also had diabetes (90378). Also, in patients with nasopharyngeal carcinoma, population research has found that consuming at least 8.6 mg daily of supplemental vitamin B6 during treatment was associated with a lower overall survival rate over 5 years, as well as a reduced progression-free survival, when compared with non-users and those with intakes of up to 8.6 mg daily (107134).

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