Cranberry Extract by 21st Century

EFFECTIVE

• Dyspepsia. Oral calcium carbonate is approved by the US Food and Drug Administration (FDA) as an antacid. Details: Taking calcium carbonate orally as an antacid is effective for treating dyspepsia (1843). Calcium carbonate has FDA approval as an antacid.
• Hyperkalemia. Intravenous calcium gluconate is approved by the US Food and Drug Administration (FDA) for preventing hyperkalemia-induced cardiac abnormalities. Details: Administering calcium gluconate intravenously can reverse electrocardiographic changes and arrhythmias induced by hyperkalemia (12946). Intravenous calcium gluconate is FDA-approved for preventing hyperkalemia-induced cardiac abnormalities.
• Hypocalcemia. Oral calcium treats and prevents hypocalcemia. Intravenous calcium is used to treat severe hypocalcemia. Details: Taking calcium orally is effective for treating and preventing hypocalcemia. Intravenous calcium gluconate, acetate, gluceptate, or chloride is effective for severe hypocalcemia or hypocalcemic tetany (12928).
• Kidney failure. Oral calcium carbonate or calcium acetate is used as a phosphate binder during kidney failure. Details: Taking calcium carbonate or calcium acetate orally is effective as a phosphate binder. Calcium acetate (PhosLo) appears to control hyperphosphatemia better than sevelamer (Renagel) (12943,12944,38990). Calcium citrate is not recommended for this purpose because it increases aluminum absorption and does not bind phosphate as efficiently as calcium acetate or calcium carbonate (21631). Some clinical research also shows that taking calcium orally reduces blood pressure in patients with kidney failure (975).

LIKELY EFFECTIVE

• Corticosteroid-induced osteoporosis. Oral calcium in combination with vitamin D prevents bone density loss that occurs during long-term treatment with corticosteroids. Details: Taking calcium in combination with vitamin D as adjunctive therapy seems to be effective for reducing bone mineral density loss in people using corticosteroids long-term (982,1046,1830,1831,1832,4462,4463,4464,4465,4466)(4467,12945,38493). One specific product used in clinical research is Oscal (Marion Merrel Dow Inc.), which contains elemental calcium 500 mg per tablet plus vitamin D 125 IU per tablet (982). Another product used is Oscal 250 + D (SmithKline Beecham Healthcare), which contains elemental calcium 250 mg and vitamin D 125 IU per tablet (1046).
• Hyperparathyroidism. Oral calcium reduces parathyroid hormone levels in patients with secondary hyperparathyroidism due to kidney failure. Details: Taking calcium orally reduces parathyroid hormone levels in patients with kidney failure and secondary hyperparathyroidism (1827,1828,1829,39174,39425). In elderly women, the combination of calcium and vitamin D reverses secondary hyperparathyroidism and reduces hip fracture risk (8818). Also, population research suggests increased calcium intake from the diet and supplements reduces the risk of primary hyperparathyroidism in women. Supplemental intakes of at least 500 mg/day and dietary intakes of approximately 1100 mg/day are considered to be protective (91353).
• Osteoporosis. Adequate calcium intake, from the diet and/or supplements, is recommended for the prevention and treatment of osteoporosis. Details: The Bone Health and Osteoporosis Foundation (BHOF) recommends ensuring adequate calcium intake in line with the recommended dietary allowance (RDA) by age, along with adequate vitamin D intake, for the prevention and treatment of osteoporosis in adults over 50 years of age. Supplementation can be used to augment dietary intake when adequate dietary intake is not feasible (109425). In the US and Canada, foods containing at least 200 mg calcium with less phosphorous content than calcium can be labelled with a health claim regarding the relationship between adequate calcium intake and a reduced risk for osteoporosis (11940,102148). However, calcium supplementation is not recommended specifically for the primary prevention of osteoporosis. The US Preventive Task Force (USPSTF) states that the current evidence is insufficient to assess the balance of benefits and harms of vitamin D and calcium supplementation, alone or in combination, for the primary prevention of fractures in community dwelling adults without osteoporosis (95695). Also, calcium supplements do not seem to be effective for preventing loss of bone mineral density (BMD) during lactation (988), in patients who have had bone marrow transplantation (1817), or in patients who have had renal transplantation (4823,38736,38871). Maximal bone growth occurs in the teenage years, and then BMD in females remains relatively constant until age 30-40. After age 40, bone loss typically occurs at rates of 0.5% to 1% per year. In males, this occurs several decades later. Bone loss is more pronounced if dietary calcium intake is below the RDA, which is the case for many Americans (2571,2578). One meta-analysis of randomized controlled trials in healthy children 7-14 years old shows that fortifying food with calcium 250-1000 mg daily for up to 24 months modestly improves femoral neck BMD, but not hip or spine BMD. However, the included trials did not supplement vitamin D (107232). During the 5 years immediately after menopause, calcium supplementation has very little effect on bone loss (2569,2570,2575,2576). The rapid loss of estrogen causes a high bone resorption rate, which increases serum calcium levels and therefore decreases intestinal absorption of calcium (2570). After this period, the typical rate of bone loss is 2% per year (2572,2576). Taking calcium 1000-1600 mg daily as carbonate, citrate, lactate gluconate, or citrate malate salt decreases this rate by 0.25% to 1% annually (977,979,981,2569,2571,2572,2575,2576,2578,6850)(38978,38980,39064). The greatest reductions (1% or more) are seen in the first 1-2 years of supplementation when bone remodeling foci can be filled (2569,2576). After this period, the differences in rate of loss between supplemented and non-supplemented females are closer to 0.25% per year (2569,2577). A meta-analysis of clinical evidence suggests that there is no additional benefit after 4 years (38980). Small clinical studies have found that continuous calcium supplementation at an average daily dose of 1050 mg, started after menopause and continued for 1.5-4 years, may reduce fracture rates by 26% when compared with no calcium supplementation. The largest of these studies was conducted in nursing home residents who also received daily vitamin D; the benefits of calcium, specifically, are unclear (39386). Some research also suggests that calcium and vitamin D improves primary prevention of osteoporotic fractures in some older individuals with osteoporosis, particularly the elderly and those who are no longer community dwelling (12930,38875,38849,39026,109471). However, not all research is positive. One large clinical trial in elderly adults with a low-trauma fracture show that taking calcium 1000 mg daily with or without vitamin D 800 IU daily for 2-7 years does not reduce the risk of a second fracture when compared with placebo (13073). Another clinical study shows that taking calcium 1000 mg daily plus vitamin D 800 IU daily does not prevent a second fracture in elderly patients, or prevent a first fracture in elderly patients with other risk factors such as low body weight (less than 58 kg, 127.6 pounds), smoking, family history of hip fracture, or fair or poor self-reported health (12929). Also, some exploratory research suggests that supplements may need to be continued indefinitely; in adults over 68 years of age, any effects of 2 years of calcium supplements on BMD appear to be lost within 2 years after discontinuing supplements (6853). Calcium has additive effects when used with other agents such as vitamin D, estrogens, or calcitonin. Whereas calcium alone generally reduces or prevents loss of BMD, combination with other agents can produce small increases in BMD ranging from 0.3% to 3.3% depending on the combination and dosages used (978,980,1836,2570,2571,2572,2576). However, one meta-analysis in healthy adults shows that fortifying foods with calcium 250-1000 mg daily, in conjunction with vitamin D supplementation, for up to 24 months does not improve BMD when compared with control (107232). The full potential of osteoporosis treatments cannot be realized without adequate calcium intake (2569,2570,2571,2572). Advise patients taking agents such as estrogens, calcitonin, bisphosphonates, or raloxifene (Evista) to ensure that their daily calcium intake meets the RDA. Use supplements if necessary. The usefulness of calcium in preventing osteoporosis in males is not as well-studied. Some observational research has found that calcium 870 mg daily is not associated with changes in BMD and bone loss in males (97201). However, clinical evidence suggests that taking calcium 1000 mg daily for 2 years might improve trabecular or cortical bone mass by 2% to 4% (980,8827,8873). Dietary supplementation with calcium and vitamin D seems to moderately reduce bone loss measured in the femoral neck, spine, and total body, and seems to reduce the incidence of nonvertebral fractures in older patients with osteopenia or low BMD (980).
• Premenstrual syndrome (PMS). Adequate calcium intake seems to prevent symptoms of PMS. Details: There seems to be a link between low dietary calcium intake and symptoms of PMS (2004,6847,39007). Taking calcium 1000-1336 mg daily seems to significantly reduce depressed mood, water retention, and pain, especially if daily calcium intake is inadequate (1822,1823,1824,2004,95821). Calcium carbonate 1200 mg daily seems to decrease PMS symptom scores by about 18% when compared with placebo (1822). Increasing dietary calcium intake is also associated with a decreased risk of developing PMS. Consuming an average of 1283 mg of calcium per day from foods is associated with about a 30% lower risk of developing PMS compared with consuming an average of 529 mg daily (13094); however, taking calcium supplements does not appear to be associated with the risk of developing PMS.

POSSIBLY EFFECTIVE

• Colorectal cancer. Oral calcium seems to be beneficial for preventing colorectal cancer, especially in those with adequate vitamin D levels and normal body mass index (BMI). Details: Population studies have found that increased intake of dietary or supplemental calcium is associated with a reduced risk of colorectal cancer and colorectal adenomas (1047,8820,12120,38951,98898,98899). Clinical trials and meta-analyses of clinical research also show that taking calcium supplements 1.2-2 grams daily for up to 4 years can reduce the risk of colorectal adenoma recurrence by up to 29% (970,12118,12950,15267,34596,38718,39042,95817). However, not all research has been positive. Some meta-analyses of clinical research or observational studies suggest that taking calcium does not reduce the risk of familial adenomatous polyposis or colorectal cancer (34596,39042,39349). Other contradictory research suggests that postmenopausal females who take calcium 1000 mg daily plus vitamin D 400 IU daily do not have a reduced risk of developing colorectal cancer (14290); however, this finding may not be reliable due to the high baseline intake of calcium in study participants. The reason for these conflicting findings is not entirely clear. Vitamin D might be an important factor. People with lower than average vitamin D levels do not seem to get any benefit from calcium supplements (12118). Also, one meta-analysis of previous trials suggests that taking calcium 1200 mg daily reduces the risk of colorectal adenomas in people with a normal BMI, but not in those who are overweight or obese (99715). Despite this conflicting evidence, the US Food and Drug Administration (FDA) approved a qualified health claim in 2005 stating that calcium supplements may reduce the risk of colorectal cancer and colorectal adenomas. However, the FDA has determined that there is little scientific evidence to support this claim (102366).
• Fetal bone mineralization. If calcium intakes are low during pregnancy, oral calcium seems to be beneficial for increasing fetal bone density. Details: With low dietary calcium intake (less than 562 mg elemental calcium daily) during pregnancy, calcium supplementation increases fetal bone mineralization and density. However, calcium supplementation does not offer any additional benefit if calcium intakes are adequate (3263,3264).
• Hypertension. Oral calcium seems to reduce blood pressure by a small amount. However, it is unclear if this reduction is clinically significant. Details: Many clinical trials and observational studies show that intake of calcium supplements or dietary calcium modestly reduces blood pressure in patients with or without hypertension, usually around 1-2 mmHg. Calcium seems to be more effective for certain subpopulations of patients, such as salt-sensitive people and patients with low baseline dietary calcium intake (945,972,974,976,984,1818,1819,1820,1821,6852)(13138,14406,38803,39063,39094,39221). Also, a meta-analysis of clinical research shows that calcium intake during pregnancy reduces systolic blood pressure in offspring by 1-2 mmHg (38852). However, a large-scale clinical trial in postmenopausal females shows that taking vitamin D (cholecalciferol) 400 IU daily in combination with elemental calcium 1000 mg daily does not lower blood pressure or reduce the risk of developing hypertension (16714). Additionally, a meta-analysis of 8 clinical trials shows that taking calcium in combination with vitamin D for up to 7 years has no effect on blood pressure (98861). The validity of this finding is limited by the poor methodological quality of the included studies. Some observational research suggests that calcium can reduce the risk for hypertension. Population research in females aged 45 years and older suggests that higher intake of calcium from both diet and supplement sources is linked to a lower risk of developing hypertension when compared to lower calcium intake (14265). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim stating that calcium supplements may reduce the risk of hypertension. However, the FDA has concluded that this claim is based on supporting, rather than conclusive, evidence (102367).
• Osteomalacia. Oral calcium seems to reverse osteomalacia caused by very low calcium intakes. Details: Osteomalacia is commonly caused by vitamin D deficiency; however, very low calcium intake can also lead to osteomalacia in children and adults. Calcium supplementation can reverse osteomalacia caused by calcium deficiency. Along with appropriate vitamin D supplementation, individuals at risk of osteomalacia need sufficient calcium intake (94819).
• Pre-eclampsia. Oral calcium seems to reduce the risk of pre-eclampsia in high risk pregnancies, especially if calcium intakes are low. Details: Although there is some conflicting evidence (971,38756), most clinical research shows that taking calcium orally 1-2 grams daily reduces pregnancy-related hypertension and pre-eclampsia (973,1833,8828,39043,39319,39426,96480). Calcium appears to reduce the risk of pre-eclampsia by about 50% when compared with placebo. One meta-analysis of 19 controlled trials involving over 29,000 pregnancies found that for every 19 females treated with calcium, one episode of pre-eclampsia would be avoided (96480). Calcium appears to have the greatest effect in individuals at high-risk of pre-eclampsia or with low calcium levels, and when taken at greater than or equal to 20 weeks of gestation (15029,38497,96480,99714). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim regarding the use of calcium supplements to reduce the risk of pregnancy-induced hypertension and pre-eclampsia. However, due to the limited and conflicting research available at that time, the FDA stated that this outcome was highly unlikely. Since then, large, high-quality clinical research has supported this finding. In fact, in 2016 the World Health Organization (WHO) released a recommendation to prescribe oral calcium supplementation 1.5-2 grams daily during pregnancies at high risk of pre-eclampsia if dietary calcium intakes are low, in order to prevent pre-eclampsia (97347).
• Rickets. Oral calcium seems to reverse rickets caused by very low calcium intakes. Details: Rickets is commonly caused be vitamin D deficiency; however, very low calcium intake can also lead to rickets. Calcium supplementation can reverse rickets caused by calcium deficiency (94819). A small clinical study in children with nutritional rickets shows that taking calcium 500-2000 mg daily for 24 weeks improves radiographically measured rickets caused by calcium deficiency. Rickets seems to improve more rapidly with calcium 1000 mg compared to calcium 500 mg. However, increasing the calcium dose to 2000 mg daily is not more beneficial than calcium 1000 mg daily (98904).
• Tooth retention. Oral calcium with vitamin D seems to help with tooth retention in the elderly population. Details: A clinical trial in the elderly population shows that taking calcium citrate malate 500 mg daily along with vitamin D3 (cholecalciferol) 700 IU daily orally for 3 years reduces the risk of tooth loss by about 52% when compared with placebo (8816).

POSSIBLY INEFFECTIVE

• Breast cancer. Oral calcium does not seem to be beneficial for breast cancer prevention. Details: Although some population research disagrees (15631,39041,95811,107237), most research shows that increased calcium intake is not associated with a reduced risk of breast cancer (15631,16715,98895,107236,107237). Subgroup analyses of population research suggest that calcium intake may reduce the risk of breast cancer in postmenopausal, but not pre-menopausal, adults (15631,107237). Another subgroup analysis in a large meta-analysis of population research also suggests that dietary intake may reduce estrogen receptor(ER)-negative breast cancer, but not ER-positive breast cancer (107236). However, most other research has not evaluated the effects of calcium supplementation or intake on breast cancer subtypes. The best evidence to date, from a large scale clinical trial (Women's Health Initiative), shows that taking vitamin D (cholecalciferol) 400 IU daily plus calcium 1000 mg daily for 7 years after menopause does not reduce the risk of developing invasive breast cancer at the end of the study and 5 years after the end of the intervention (16715,98895).
• Fractures. Although oral calcium prevents fractures in osteoporosis, most evidence shows that calcium does NOT prevent factures in people who do not have osteoporosis. See Osteoporosis discussion for more information on the use of calcium for this purpose. Details: The most recent and robust meta-analysis of clinical research shows that calcium supplementation with or without vitamin D is NOT associated with reduced fractures in older adults without osteoporosis (95822). A large-scale study in postmenopausal females aged 50-79 years suggests calcium 1000 mg plus vitamin D 400 IU daily for 7 years only modestly improves bone mineral density (BMD) and does not significantly reduce fracture risk. This lack of effect may have been due to low adherence to the treatment regimen. In those who were 80% adherent, the combination of calcium plus vitamin D reduced the risk of hip fracture by about 29% (14282). Also, some clinical research shows that taking calcium carbonate 1000 mg and vitamin D 400 IU for 5 years does not attenuate loss of height after menopause when compared with placebo (95810). Additional meta-analyses of clinical and observational evidence suggest that calcium supplementation is not associated with a reduced risk of vertebral or nonvertebral fractures, such as hip fractures (38589,38888,98895). Some other research has suggested that calcium in combination with vitamin D reduces fracture risk in older patients without osteoporosis (980,1836,8818,12930,12933,12952,38849,102145,107235); however, this research is confounded by a number of variables, including the presence of hormonal therapy and differing levels of fracture risk at baseline (1836,8818,95822). Conflicting findings on this topic might also be due to genetic differences in patient populations. A population analysis of the Women's Health Initiative study found that, in older females with the lowest genetic susceptibility to low bone mineral density (BMD), taking calcium with vitamin D is associated with a reduction in fracture risk. However, in females with a higher genetic susceptibility to low BMD, there is no association between supplementation and fracture risk. This might be because individuals with a lower susceptibility to low BMD are also more responsive to calcium and vitamin D supplementation (97357). As of April 2018, the U.S. Preventative Services Task Force (USPSTF) concludes that there is insufficient evidence to determine whether supplementing with vitamin D >400 IU daily along with calcium >1000 mg daily is safe and effective for preventing fractures in community dwelling adults without vitamin D deficiency, osteoporosis, or a history of fracture. USPSTF recommends against supplementing with calcium 1000 mg daily or less along with vitamin D 400 IU daily or less for preventing primary fractures in community-dwelling postmenopausal females (95695).
• Obesity. Oral calcium does not seem to improve weight loss. Details: Observational research has found that adults and children with low calcium intake are more likely to gain weight, have a higher body mass index (BMI), and be overweight or obese when compared to people with high calcium intake (12124,12125,12126,12127,14265). Additional observational research has found that increasing calcium intake is associated with weight loss in females; the results in males have been conflicting (12127,15602,15603). Despite these findings from observational research and a few small clinical studies (12128,15397,14438,98905), most clinical research has found that increased calcium intake does not increase weight loss (12052,13138,15396,15399,38985,39004,97356). The most recent meta-analysis of 20 clinical studies shows that daily dietary and supplemental calcium intake that meets the dietary reference intake (DRI) of 1000 mg or more daily does not increase weight loss in overweight individuals or patients with obesity when compared with intake below the DRI (95813). An older meta-analysis of 13 clinical trials also shows that increased dietary and supplemental calcium intake does not increase weight loss (15605).
• Overall mortality. Oral calcium does not seem to reduce overall mortality. Details: While some population research has found that calcium taken in combination with vitamin D in older females is associated with a lower risk of death (97353), most evidence shows that calcium, with or without vitamin D, has no effect on all-cause mortality (93533,97308).

INEFFECTIVE

• Cardiovascular disease (CVD). Oral calcium does not reduce the risk of developing CVD and may actually increase risk in some patients. Details: Clinical research shows that calcium does not decrease CVD risk. Several separate meta-analyses of clinical and population research involving over 50,000 patients show that taking calcium 600-1200 mg daily for up to 7 years does not reduce the risk of CVD-related outcomes, including stroke and myocardial infarction, cardiovascular death, or overall mortality (39018,91350,92994,93533,97308,98902,107231,107233). No association was found between total dietary or supplemental calcium intake with or without vitamin D and the risk of CVD or mortality (91350,93533,97308). In fact, some population and clinical research has found that when calcium is used alone or with vitamin D, there is an INCREASED risk of CVD and coronary heart disease (38077,107233). However, other clinical research disagrees (93533). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of CVD and coronary heart disease by 1.1-1.2 times when compared with control. However, the majority of the included research evaluated postmenopausal females and it is unclear if this finding is applicable to other populations (107233).
• Chemotherapy-induced peripheral neuropathy. Intravenous calcium does not prevent nerve pain in patients given oxaliplatin. Oral calcium has not been evaluated for this purpose. Details: While pooled analyses of cohort studies and randomized controlled trials suggest that calcium and magnesium infusion decreases the incidence of oxaliplatin-induced neurotoxicity, a meta-analysis of only randomized controlled trials shows that the infusion has no effect in preventing neurotoxicity (90028,90029,90031). Additionally, clinical trials show that administering calcium gluconate 1 gram with magnesium sulfate 1 gram intravenously immediately before, or before and after, the administration of a single oxaliplatin cycle (90005), or over the entire 6-cycle course of oxaliplatin, does not improve symptoms of neurotoxicity when compared with placebo (96474).
• Myocardial infarction (MI). Oral calcium does not prevent MI. When taken in the absence of vitamin D, oral calcium may increase the risk of MI. Details: Population research has found that increased dietary intake of calcium is associated with a decreased risk of MI (91350). However, a 2010 meta-analysis of clinical research shows that taking calcium at a dose of at least 500 mg daily is associated with an approximate 30% INCREASE in the risk of MI in patients over the age of 40. According to this analysis, one additional case of MI will occur for every 69 patients that take calcium for 5 years (17482). A more recent meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of MI by 1.2 times when compared with control. However, the majority of the included research studied postmenopausal females and it is unclear if this finding is applicable to other populations (107233) In contrast, other meta-analyses of clinical research have shown that taking calcium for up to 7 years is NOT associated with an increased risk of MI, including a meta-analysis that only included postmenopausal females (93533,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of MI in postmenopausal females (93533). Also, the association between calcium supplementation and MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Alcohol use disorder. It is unclear if oral calcium is beneficial for alcohol use disorder. Details: Preliminary clinical research shows that taking calcium carbonate 800 mg and vitamin D 200 IU orally daily for 14 days modestly reduces alcohol craving scores and withdrawal scores when compared with placebo in adults with alcohol dependence that are undergoing withdrawal. Taking calcium carbonate did not reduce the need for diazepam; however, the study may have been inadequately powered to detect a difference between groups (107234).
• Atherosclerosis. It is unclear if oral calcium is beneficial for atherosclerosis. Details: A population study has found that taking calcium 1.2 grams daily for 3 years has no effect on carotid intima thickness or carotid atherosclerosis incidence. A total calcium intake (dietary and supplemental) of at least 1794 mg daily in older females may be associated with a decreased risk of carotid atherosclerosis when compared with a total calcium intake below 1010 mg daily (97351).
• Autism spectrum disorder. It is unclear if oral calcium during pregnancy is beneficial for reducing the odds of autism spectrum disorder in the offspring. Details: A small observational study found that calcium supplementation during pregnancy is associated with a 52% reduced odds of an autism spectrum disorder in the offspring (98900).
• Cancer. Oral calcium alone does not seem to prevent cancer. It is unclear if oral calcium with vitamin D is beneficial for preventing cancer. Details: Taking calcium alone does not seem to significantly reduce the risk of cancer (12118,15629). The role of calcium in cancer prevention when taken along with vitamin D is controversial, as conflicting results exist. One clinical trial shows that healthy postmenopausal females who take supplemental calcium 1400-1500 mg daily plus vitamin D3 (cholecalciferol) 1100 IU daily have a 60% lower relative risk for developing cancer of any type. Approximately 25 postmenopausal females would need to take this combination for 4 years to prevent one occurrence of cancer (15629). However, a more recent clinical study shows that healthy postmenopausal females who take supplemental calcium 1500 mg daily plus vitamin D3 (cholecalciferol) 2000 IU daily do not have a reduced risk of cancer at 4 years (93943). Reasons for the disparate results are not entirely clear. The discrepancies do not appear to be related to baseline vitamin D levels or different study populations. It is possible that, given the 10-year time lapse between the two publications, the discrepancies result from differences in cancer detection capability. Also, since cancer risk was a secondary outcome measure in the earlier study and a primary outcome measure in the more recent study, it is possible that the discrepancies result from differences in statistical methodologies. The effect of vitamin D and calcium on cancer risk in males and younger patients is not known. There is also interest in using calcium for reducing the risk of hematological malignancies. An analysis of the Women's Health Initiative study shows that taking calcium 1000 mg daily in combination with vitamin D3 400 IU for up to 10 years is associated with a 20% reduction in the risk of hematologic malignancies when compared with placebo. However, no effect on hematologic malignancy related mortality was seen (97354).
• Depression. It is unclear if oral calcium is beneficial for depression prevention. Details: Population research has found no association between a higher dietary intake of calcium and the risk of depression when compared with a lower dietary intake of calcium (96480).
• Diabetes. It is unclear if oral calcium is beneficial for type 2 diabetes prevention. Details: Some population research has found that a higher intake of calcium from diet or supplements, alone or in combination with vitamin D, is associated with a lower risk of developing type 2 diabetes when compared with lower calcium intake (14265,16713,96473). However, population research is often limited by confounding variables. For example, one analysis found that any beneficial effect might be influenced by concomitant magnesium intake (96473). Furthermore, other population research has found that serum calcium levels higher than 9.6 mg/dL are associated with greater risk of developing diabetes in Chinese adults with osteoporosis. This study is limited because it was not determined whether increased serum calcium was due to increased calcium intake or another factor such as parathyroid function (95815).
• Dysmenorrhea. It is unclear if oral calcium is beneficial for reducing pain associated with dysmenorrhea. Details: Clinical research shows that taking calcium carbonate 1000 mg with vitamin D 5000 IU daily for three menstrual cycles does not reduce pain when compared with placebo in patients with primary dysmenorrhea (95821). However, calcium carbonate 1000 mg taken alone seems to reduce pain when compared with placebo.
• Endometrial cancer. It is unclear if oral calcium is beneficial for endometrial cancer prevention. Details: A meta-analysis of population research suggests that calcium supplements may reduce the risk of endometrial cancer, but dietary calcium does not seem to have any effect (38893).
• Fall prevention. It is unclear if oral calcium with vitamin D is beneficial for preventing falls. Details: Research suggests that calcium in combination with vitamin D, but not calcium alone, might prevent falls by decreasing body sway and normalizing systolic blood pressure (6362,11939,39038). Some experts think the combination of calcium and vitamin D may be important (11916). Preliminary clinical research in adults residing in a health care facility shows that taking vitamin D supplements while increasing dietary calcium and protein for 2 years reduces falls by 11% when compared with standard diets. Intervention diets were supplemented with milk, yogurt, and cheese to provide calcium 1142 mg and protein 69 grams daily (107235). There might also be different effects in females compared to males. In one study, females aged 65 years or older who took vitamin D 700 IU plus calcium citrate 500 mg daily over a 3-year period had a 46% lower risk of falling. However, this combination did not decrease falls in males (14291).
• Fluorosis. Oral calcium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Taking calcium orally, in combination with ascorbic acid (vitamin C) and vitamin D, seems to be effective for reducing excessive fluoride levels in children and improving symptoms of fluorosis in children aged 6-12 years (990).
• Heart failure. It is unclear if oral calcium in combination with vitamin D is beneficial for preventing heart failure. Details: Based on a secondary analysis of a large-scale clinical trial (Women's Health Initiative), taking calcium 1000 mg with vitamin D 400 IU daily does not reduce the risk of heart failure in the overall population or in individuals at high risk. However, in a subgroup of postmenopausal females without risk factors for heart failure, calcium and vitamin D supplementation might reduce the risk of developing heart failure by about 37% (97307).
• Hypercholesterolemia. It is unclear if oral calcium is beneficial for hypercholesterolemia. Details: Some evidence shows that taking calcium carbonate 400 mg three times daily reduces low-density lipoprotein (LDL) cholesterol levels by 4% and increases high-density lipoprotein (HDL) cholesterol levels by 4% after 6 weeks of treatment when used in combination with a low-fat diet (American Heart Association Step 1) (2557). In contrast, a study in females with dyslipidemia shows that taking calcium 800 mg daily for 2 years might INCREASE total cholesterol levels by about 12 mg/dL when compared with placebo. This same study showed an association between calcium supplementation and an increase in total cholesterol levels and carotid intimal thickness in postmenopausal females, but not premenopausal females (97350). A recent meta-analysis of randomized controlled trials which included both healthy patients and patients with dyslipidemia shows that taking calcium 500-2000 mg daily and vitamin D 200-7142 IU daily modestly improves HDL cholesterol and triglyceride levels, but not LDL cholesterol levels, when compared with placebo. Subgroup analyses suggest that calcium and vitamin D supplementation is more effective in patients with dyslipidemia at baseline. It is unclear if this effect is due to calcium, vitamin D, or the combination (107227). However, other research shows that taking a specific supplement containing calcium 600 mg plus vitamin D 200 IU (Caltrate 600 D, Wyeth Consumer Healthcare Inc.) twice daily in combination with calorie restriction does not reduce total or LDL cholesterol levels when compared with placebo (15601).
• Lead toxicity. It is unclear if oral calcium is beneficial for reducing blood levels of lead. Details: Lead is mobilized along with calcium from bone during pregnancy and lactation, resulting in increased serum concentrations of lead. One clinical study suggests that calcium supplementation does not significantly decrease these elevated lead concentrations (1586). However, another clinical study suggests that taking calcium reduces blood lead levels by 11% when compared with placebo, with greatest effects observed in those with high baseline levels of lead (38957).
• Lyme disease. Although there is interest in using oral calcium for Lyme disease, there is insufficient reliable information about the clinical effects of calcium for this condition.
• Metabolic syndrome. It is unclear if oral calcium alone or with vitamin D is beneficial for metabolic syndrome prevention. Details: Population research has found that a higher intake of calcium from diet and supplements alone, or in combination with vitamin D, is associated with a lower risk of developing metabolic syndrome when compared with lower calcium intake (14265,16713).
• Nephrotic syndrome. It is unclear if oral calcium with vitamin D is beneficial for preventing nephrotic syndrome. Details: Clinical research shows that taking calcium 500-1000 mg daily for 3 months in combination with vitamin D3 60,000 IU daily or weekly for 4 weeks has no effect on bone mineral density or the risk of relapse in children with steroid-sensitive nephrotic syndrome (97355).
• Nonmelanoma skin cancer. It is unclear if oral calcium is beneficial for preventing keratinocyte carcinomas. Details: In middle aged and older adults recently diagnosed with a colorectal adenoma, clinical research shows that taking calcium 1200 mg daily as calcium carbonate for 3-5 years does not reduce the incidence of keratinocyte cancer when compared with placebo over a median of 8 years. A sub-group analysis shows that taking calcium alone or with vitamin D3 1000 IU daily reduced the risk of invasive cutaneous squamous cell carcinoma by a moderate amount, but had no effect on the risk of basal cell carcinoma (104622).
• Oral mucositis. When used in combination with fluoride treatments, a calcium phosphate mouth rinse seems to prevent and reduce mucositis-related pain in patients undergoing hematopoietic stem cell transplantation (HSCT). Details: A small clinical study in patients undergoing HSCT shows that using a particular mouth rinse (Caphosol, EUSA Pharma) containing calcium phosphate, in combination with fluoride treatments, reduces days of mucositis, the duration of pain, and the dose and days of morphine used when compared with placebo and fluoride treatment (38611).
• Ovarian cancer. It is unclear if oral calcium is beneficial for ovarian cancer prevention. Details: An older meta-analysis of 12 cohort studies found that dietary calcium intake is not associated with a reduced risk of ovarian cancer (38792). However, a more recent pooled analysis of 15 cohort and case-control studies has found that the highest intake of dietary or dairy calcium is associated with a 20% lower risk of ovarian cancer when compared to the lowest intake (97349).
• Postpartum depression. It is unclear if oral calcium is beneficial for reducing postpartum depression risk. Details: Preliminary clinical research shows that taking calcium 2 grams daily beginning at 11-21 weeks gestation reduces depression at 12 weeks postpartum when compared with placebo. However, no benefit is seen at 6 weeks postpartum (39447).
• Pregnancy-related leg cramps. It is unclear if oral calcium is beneficial for preventing leg cramps during pregnancy. Details: A small clinical study shows that taking calcium 1 gram twice daily (as a mixture of salts) for 2 weeks can reduce pregnancy-related leg cramps during the second half of pregnancy when compared with no treatment (2567).
• Prostate cancer. It is unclear if oral calcium is beneficial for prostate cancer prevention. Details: Some clinical research shows that taking calcium 1200 mg daily might decrease the risk of developing prostate cancer (14133). However, some epidemiological research suggests that consuming very high doses of calcium, over 2000 mg daily, might actually increase the risk of developing prostate cancer (14134). Some epidemiological research also suggests that doses greater than 1500 mg daily increase the risk of poorly differentiated, clinically advanced, and fatal prostate cancer (14132). Consumption of dairy products has also been weakly linked to a modest increase in risk of prostate cancer (98894). However, contradictory research suggests that there is no association between dietary intake of calcium and overall risk of prostate cancer (14131,14132,104630).
• Stroke. It is unclear if oral calcium is beneficial for stroke prevention. Details: Some population research has found that increasing dietary calcium intake is associated with a decreased risk of ischemic stroke (4822,38678). However, other population research has found that increasing dietary calcium intake is not associated with a decreased risk of stroke (91350). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years does not affect the risk of stroke when compared with control. However, the majority of the included research evaluated postmenopausal females, and it is unclear if this finding is applicable to other populations (107233).
• Vertigo. Oral calcium with vitamin D might reduce positional vertigo; the effect of calcium when used alone is unclear. Details: A large clinical study in adults with recurrent benign paroxysmal positional vertigo shows that taking calcium 500 mg and vitamin D 400 IU twice daily for one year reduces annual recurrence of vertigo by 27% when compared with no treatment. The number needed to treat to prevent vertigo was 3.7 (103681). It is unclear if this benefit is due to vitamin D, calcium, or the combination. More evidence is needed to rate calcium for these uses.

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POSSIBLY EFFECTIVE

• Urinary tract infections (UTIs). Cranberry products may possibly reduce the risk of repeat, symptomatic UTI in females with recurrent UTI, in children, and in people susceptible to UTI following kidney transplant, urogenital surgery, or radiation therapy near the urogenital system. While some positive evidence exists, most research suggests that cranberry products do not seem to reduce the risk of UTI in older adults in institutions, pregnant patients, or adults with neuromuscular dysfunction of the bladder. Cranberry is not recommended for the treatment of UTI in any population. Details: Cranberry appears to reduce the risk of UTI in some populations but not others. In healthy females at an increased risk of UTI or history of recurrent UTI, meta-analyses of clinical trials show that cranberry products decrease the overall risk of recurrent or first-time UTI by 26% to 35% (46473,92578,96739,111407). In 2019, the American Urological Association published guidelines stating that, based on low certainty evidence, clinicians may offer cranberry tablets or juice as prophylaxis for females with recurrent UTIs. Due to a lack of compelling evidence for any specific product, the guidelines recommend choosing formulations based on availability and tolerability (100855). In 2020, the US Food and Drug Administration (FDA) approved qualified health claims stating that consuming cranberry juice in doses of at least 8 ounces daily, or cranberry supplements in doses of at least 500 mg daily, may help reduce the risk of recurrent UTI in healthy females. However, the FDA has concluded that there is limited scientific evidence to support these claims (103302). The benefits of cranberry for prevention of UTI during pregnancy are unclear. Subgroup analysis of meta-analyses suggest that cranberry supplementation does not reduce the risk of UTI in pregnant adults compared with placebo or no treatment (100855,111407). A preliminary clinical study shows that drinking cranberry juice 240 mL three times daily until delivery does not reduce the frequency of asymptomatic bacteriuria or symptomatic UTI during pregnancy, although the study was not adequately powered to detect a difference in these outcomes (16415). In contrast, one preliminary clinical trial shows that UTI frequency was reduced in 70.5% of those ingesting cranberry juice 250 mL four times daily, compared with only 32% of those taking placebo (93670). In children, a meta-analysis shows that taking cranberry products probably reduces the risk of subsequent symptomatic UTIs by up to 54% compared with placebo or no treatment, but does not specify a particular formulation (111407). Clinical trials show that daily consumption of cranberry syrup (Pharmatoka), cranberry juice (Cranberry UR-50, Kikkoman Company) 100 mL, cranberry-lingonberry juice 50 mL, and cranberry extract (Anthocran) 120 mg reduce the risk of UTI recurrence in children (46452,96733,96737,108055). In contrast, another clinical trial shows that drinking cranberry juice (Ocean Spray Cranberries, Inc) 5 mL/kg daily for 6 months does not reduce the incidence of recurrent UTI when compared with placebo, although it does decrease the total number of UTI episodes and length of antimicrobial therapy per child (46470). In older, institutionalized adults, a meta-analysis of 5 studies evaluating the effectiveness of cranberry products shows little or no benefit in preventing symptomatic, culture-verified UTIs (111407). A clinical study in females residing in long-term care (LTC) facilities shows that taking a specific cranberry supplement (Ellura, Pharmatoka) once daily for 1 year does not reduce the incidence of UTI or asymptomatic bacteriuria (92517). However, clinical trials of cranberry products in elderly patients in LTC facilities suggest that cranberry may be more effective in patients at a higher risk for UTIs, such as those with diabetes, long-term catheterization, or recurrent UTIs (90041,108055), and in patients with E. coli-related UTIs (46389,46472). In one small study, providing all patients living in a LTC facility with 4 ounces of cranberry juice or six tablets of a specific concentrated cranberry product (Azo-Cranberry, i-Health, Inc.) daily for 13 months decreased the facility's overall monthly UTI rate from 27.7 to 20.7 (46492). In another clinical trial, taking cranberry juice cocktail (Ocean Spray Cranberries, Inc) 300 mL daily for 6 months decreased the rate of asymptomatic bacteriuria plus pyuria by 13% in older females living in institutional settings (7008). In another clinical trial, taking a cranberry capsule 500 mg, standardized to 1.8% PACs, twice daily for 12 months decreased the risk of UTI by around 26% in patients at high-risk for UTI, including those with catheters, diabetes, or at least one UTI in the previous 12 months (90041). Meta-analyses and clinical research show that cranberry products do not reduce the risk of UTI associated with neurogenic bladder, neuromuscular dysfunction, or insufficient bladder emptying in adults or children (2811,6759,11980,46379,46425,46473,90044,92578,96737,108055,111407). However, one study found benefit in patients with neurogenic bladder due to spinal cord injury taking cranberry capsules (Cran-Max, Proprietary Nutritionals, Inc.) 500 mg daily (46443). Cranberry products have also been evaluated in a variety of other high-risk populations, with mixed results. A meta-analysis of 7 studies shows that cranberry products reduce the risk of UTIs in people with increased susceptibility to UTI due to an intervention (e.g., kidney transplant, radiotherapy to urogenital system, or urogenital surgery) when compared with placebo (111407). Cranberry extracts do not seem to reduce the risk of UTIs in individuals undergoing hysterectomy and/or anterior vaginal repair (46465), pelvic floor surgery (104245), or in patients with multiple sclerosis (46496,111407). Taking cranberry powder capsules (NurtiCran90, Petefa AB) 550 mg three times daily for 5 days does not reduce the UTI rate at days 5 or 14 when compared with placebo in postoperative females with hip fracture receiving a urinary catheter; however, the study was not adequately powered to detect a difference in this outcome (96734). Other preliminary clinical research in elderly males with benign prostatic hyperplasia and a recent UTI shows that taking a standardized cranberry extract (Anthocran) 120 mg daily for 60 days reduces the UTI recurrence rate by about 62% when compared with placebo (96735). Cranberry supplements have been studied in a variety of formulations, but it is unclear whether certain cranberry formulations are better than others (111407). Most positive studies utilized oral cranberry EXTRACTS in tablet, powder, or capsule form (6760,17210,46366,46432,93669,111407). Some products (Cranberry Supreme, GNC; Cranpac, IPCA Laboratories), taken as 200 mg twice daily, were standardized to provide 100-120 mg of proanthocyanidins (PACs) daily (46432). Some of these studies used capsules containing 400 mg cranberry solids twice daily (6760) or Natural Cranberry Extract (Solgar Vitamin and Herb Co.) 800 mg twice daily (17210). However, a clinical study in healthy females with a history of UTIs shows that taking a specific cranberry extract product (Urophenol; Diana Food) does not reduce the risk of symptomatic UTI when taken at a dose of 120 mg twice daily, standardized to 15% PACs, or at a dose of 1 mg twice daily, standardized to 1% PACs. A subgroup analysis suggests that the high dose may have modest benefit in those with less than 5 UTIs a year (108054). Cranberry JUICE or syrup has yielded mixed results for the prevention of UTI in patients with a history of recurrent UTIs, with some showing significant benefit (8253,46366,96736,111407). These studies used cranberry juice 240-250 mL 1-3 times daily (46366,96736), cranberry syrup, or a combination beverage containing cranberry juice plus lingonberry juice (Maija) 50 mL daily (8253). However, other studies found no significant improvement when compared with placebo (17524,46471,90047), although some of these studies may have been inadequately powered to detect a difference (17524,46471). Cranberry products have also been compared with other treatments including antibiotics and probiotics for preventing recurrent UTI, but the results are unclear. A meta-analysis suggests that cranberry products reduce the risk of symptomatic UTIs compared to probiotics. The analysis also showed no difference in the risk of UTI between cranberry products and antibiotics, but the precision of included studies was poor (111407). In one study, taking cranberry extract capsules (Cran-Max; Proprietary Nutritionals, Inc) 500 mg daily for 6 months was as effective as trimethoprim 100 mg daily in elderly females with recurrent UTI (16720). However, taking this same cranberry product twice daily for 12 months was less effective than trimethoprim-sulfamethoxazole 480 mg once daily in younger premenopausal individuals (17176). Additional research in children with vesicoureteral reflux (VUR) shows that daily consumption of cranberry products results in UTI recurrence rates equivalent to those obtained with prophylactic antibiotics. Cranberry juice (Cranberry UR-50, Kikkoman Company) 100 mL daily was equally effective to cefaclor 5-10 mg/kg daily; cranberry syrup (Pharmatoka) 0.2 mL/kg daily was equally effective to trimethoprim 0.2 mL/kg daily (96737).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related cognitive decline. It is unclear if oral cranberry is beneficial for age-related cognitive decline. Oral cranberry may be beneficial for improving visual episodic memory in healthy, elderly adults, but its effects on other aspects of cognition are unclear. Details: A clinical study in healthy adults aged 50-80 years shows that taking a freeze-dried cranberry powder 4.5 grams twice daily (standardized to provide 281 mg proanthocyanidins daily), provided as a sachet and added to food or beverage for 12 weeks, improves visual episodic memory performance during a memory and recall test (Rey Complex Figure Test), but does not appear to affect other measures such as attention, orientation, fluency, language, processing speed, or short-term memory, when compared with placebo (108564). Cranberry supplementation also does not appear to affect grey matter structure; however, due to the low number of patients who completed a baseline and follow-up MRI, this study may not have been adequately powered to detect a difference between groups.
• Benign prostatic hyperplasia (BPH). Preliminary clinical research suggests that oral cranberry is beneficial for reducing BPH symptoms. Details: Preliminary clinical research shows that taking powdered dried cranberry fruit 500 mg three times daily for 6 months improves lower urinary symptoms and reduces prostate specific antigen (PSA) levels when compared with no treatment in patients 45 years of age or older with elevated PSA levels, a negative prostate biopsy, and clinically confirmed non-bacterial prostatitis (17126). Another small study in those 45 years of age and older without elevated PSA levels shows that taking a specific dried cranberry powder (Flowens, Naturex-DBS, LLC) 250-500 mg daily for 6 months reduces lower urinary tract symptoms and improves voiding and storage symptoms when compared with placebo (96738).
• Cancer. Although there has been interest in using oral cranberry for cancer, there is insufficient reliable information about the clinical effects of cranberry for this condition.
• Cardiovascular disease (CVD). Although some research suggests that oral cranberry may modestly improve some CVD risk factors, it is unclear if it is beneficial for CVD prevention. Details: A meta-analysis of 10 clinical studies shows that cranberry juice or cranberry extract seems to reduce systolic blood pressure by 3.6 mmHg and body mass index by 0.3 kg/m2 when compared with placebo. However, these improvements are unlikely to be clinically significant, and cranberry does not appear to improve diastolic blood pressure, lipid levels, glycemic control, or waist circumference (102849). The generalizability of these results is limited, as the study populations ranged from healthy adults to those with type 2 diabetes, metabolic syndrome, or coronary heart disease. A clinical crossover study in patients who are overweight or obese and have elevated blood pressure shows that drinking cranberry juice 250 mL twice daily for 8 weeks reduces ambulatory diastolic blood pressure by 2 mmHg during daytime hours, but does not improve systolic blood pressure, glycemic control, or lipid levels, when compared with placebo (108059). The validity of these findings is limited due to short duration of treatment and broad heterogeneity of patient baseline characteristics.
• Catheter-related infections. Although there has been interest in using oral cranberry for catheter-related infections, there is insufficient reliable information about the clinical effects of cranberry for this condition.
• Chronic fatigue syndrome (CFS). Although there has been interest in using oral cranberry for CFS, there is insufficient reliable information about the clinical effects of cranberry for this condition.
• Diabetes. It is unclear if oral cranberry is beneficial for diabetes. Details: A small clinical trial shows that taking cranberry supplements orally does not improve fasting serum glucose, glycated hemoglobin (HbA1C), fructosamine, triglycerides, high-density lipoprotein (HDL) cholesterol, or low-density lipoprotein (LDL) cholesterol levels in patients with type 2 diabetes (11328).
• Helicobacter pylori. There is conflicting evidence regarding the use of oral cranberry for Helicobacter pylori eradication, either as a standalone treatment or in combination with standard triple therapy. Details: Two small clinical studies show that taking cranberry juice 480-500 mL, containing 88 mg proanthocyanidins (PACs), daily in two divided doses for 2-3 months can modestly increase the H. pylori eradication rate at 8 weeks, but not at 2 weeks, when compared with placebo. However, the eradication rate was only 20% or less, which is much lower than that obtained with conventional triple therapy (46388,104248). Lower doses, as either cranberry juice or cranberry powder, do not seem to improve H. pylori eradication rates. Cranberry juice containing only 23 mg or 44 mg PACs or cranberry powder containing 36 mg or 72 mg PACs did not demonstrate benefit when compared with placebo (104248). Cranberry juice has also been studied in combination with standard triple therapy. Preliminary clinical research shows that taking cranberry juice 250 mL daily for 3 weeks along with omeprazole, amoxicillin, and clarithromycin for one week does not increase the eradication rate when compared with triple therapy plus placebo. However, the combination treatment increased the rate of H. pylori eradication when only females were considered (46439). A meta-analysis of 4 small clinical studies, including three studies already discussed, shows that taking cranberry, either as a juice or a dried powder, does not improve H. pylori eradication rate when compared with placebo, regardless of treatment duration (108060). The validity of these findings is limited by the high heterogeneity of the included studies and incomplete reporting. In asymptomatic children aged 6-16 years old with H. pylori, one clinical study shows that drinking cranberry juice 200 mL, with live or heat-killed Lactobacillus johnsonii 80 mL, daily for 3 weeks eradicates H. pylori in 15% to 22% of patients, compared with 1.5% of those receiving placebo. However, these rates are lower than those typically obtained with conventional triple therapy (46441).
• Hyperlipidemia. Oral cranberry has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Drinking a combination of cranberry, blueberry, apple, and chokeberry juice 300 mL daily for 6 weeks appears to decrease total cholesterol and increase high-density lipoprotein (HDL) cholesterol when compared to baseline in females with overweight or obesity and at least one risk factor for cardiovascular disease (111233). However, the validity of the study is limited by its small size, short duration, and lack of a comparator group. It is unclear if these effects are due to cranberry, other ingredients, or the combination.
• Kidney stones (nephrolithiasis). It is unclear if oral cranberry is beneficial for reducing the risk of kidney stones. Details: Although some preliminary clinical research shows that drinking cranberry juice 500 mL diluted in 1500 mL water daily for 2 weeks can decrease urinary excretion of oxalate in healthy males, which suggests a decreased risk of kidney stone formation (46371), other preliminary clinical research shows that both cranberry juice and concentrated cranberry extracts can increase urinary oxalate levels, suggesting an increased risk of stone formation (7074,46393).
• Memory. It is unclear if oral cranberry is beneficial for memory. Details: Preliminary clinical research in cognitively intact older adults shows that taking cranberry juice 16 ounces twice daily for 6 weeks does not improve memory when compared with placebo (46390).
• Metabolic syndrome. It is unclear if oral cranberry is beneficial for metabolic syndrome. Details: Preliminary clinical research shows that drinking cranberry juice 240 mL twice daily for 8 weeks can increase plasma antioxidant capacity when compared with placebo in adults with metabolic syndrome. However, cranberry juice does not appear to affect blood pressure, blood glucose, serum lipids, or markers of inflammation when compared with placebo in these patients (46467).
• Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral cranberry is beneficial for NAFLD. Details: Preliminary clinical research in adults with NAFLD shows that adding cranberry extract 288 mg daily to a weight loss diet for 12 weeks does not appear to affect body weight, liver enzymes, lipid levels, or steatosis grade when compared with placebo. Cranberry extract may moderately reduce insulin levels and insulin resistance (104249). However, the clinical impact of these reductions is unclear. Another clinical trial in adults with NAFLD shows that taking dried cranberry powder 144 mg daily after lunch for 6 months improves steatosis grade as measured by ultrasound, insulin sensitivity, and levels of total cholesterol and triglycerides, but does not affect liver enzyme levels, when compared with placebo. All patients also consumed a reduced-calorie diet and an undefined dose of supplemental vitamin E (108058).
• Obesity. Oral cranberry has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in females with overweight or obesity and at least one risk factor for cardiovascular disease shows that drinking a combination of cranberry, blueberry, apple, and chokeberry juice 300 mL daily for 6 weeks does not reduce body weight, body mass index (BMI), or blood pressure but might improve total cholesterol and high-density lipoprotein (HDL) cholesterol when compared to baseline (111233). However, the validity of these findings is limited by the small study size, short duration, and lack of a comparator group. It is unclear if these effects are due to cranberry, other ingredients, or the combination.
• Overactive bladder. It is unclear if oral cranberry is beneficial for overactive bladder. Details: Preliminary clinical research in otherwise healthy females shows that taking dried cranberry powder 500 mg daily for 24 weeks can reduce daily micturition by 16% and urgency episodes by 57% when compared with placebo. Patients taking cranberry powder also reported an improvement in their own perception of their bladder condition when compared with placebo (104246). Limitations of this study include a short duration, lack of a run-in period, and high drop-out rate, which interfered with the ability to meet power.
• Peristomal lesions. Although there has been interest in using oral cranberry for peristomal lesions, there is insufficient reliable information about the clinical effects of cranberry for this condition.
• Prostate cancer. It is unclear if cranberry is beneficial for preventing prostate cancer recurrence. Details: Clinical research shows that taking cranberry powder (Pacran, Naturex) 1500 mg for a mean of 30 days prior to radical prostatectomy for prostate cancer does not improve prostate tissue markers when compared with taking placebo. However, levels of prostate tissue antigen decreased by approximately 22% when compared with baseline (105127).
• Radiation-induced cystitis. Evidence for the use of cranberry juice in the prevention of radiation-induced cystitis is conflicting. Details:One small clinical study in individuals with prostate cancer shows that taking 200 mg of a cranberry extract standardized to 30% proanthocyanidins (Monoselect Macrocarpon; PharmExtracta) once daily during external beam radiotherapy for 6-7 weeks reduces the risk of lower UTI by 64% when compared with placebo (92579). However, other preliminary clinical research shows that taking cranberry capsules, standardized to contain a total of 72 mg proanthocyanidins, daily during radiation treatment for prostate cancer and for two weeks post-treatment, does not improve pain, burning, nocturia, or urinary flow symptoms from radiation-induced cystitis when compared with a beetroot placebo (104247). Additionally, preliminary clinical research in patients receiving radiotherapy for bladder or cervical cancer shows that consuming cranberry juice 250 mL daily for 2 weeks does not seem to reduce the incidence of UTIs (46469).
• Rheumatoid arthritis (RA). It is unclear if cranberry juice is beneficial in RA. Details: A clinical study in adults with RA shows that drinking reduced-calorie cranberry juice 250 mL twice daily in addition to taking fish oil 1 gram three times daily for 90 days improves disease activity score (DAS28-CRP) when compared with no supplementation. However, this combination was similarly effective to patients taking fish oil alone, suggesting that any benefits may be due to fish oil, as opposed to cranberry juice (108057).
• Upper respiratory tract infection (URTI). It is unclear if oral cranberry is beneficial for the prevention or treatment of URTIs. Details: Clinical research shows that drinking a cranberry juice beverage 450 mL daily for 70 days does not decrease the incidence of cold or flu, but may reduce cold and flu symptoms, when compared with placebo in healthy adults (90046).
• Urinary odor. It is unclear if oral cranberry is beneficial for urinary odor. Details: Preliminary clinical research shows that cranberry juice cocktail might reduce urinary odors when given orally on a regular basis to patients with urinary incontinence (3333,3334,8254). Cranberry juice cocktail up to 237 mL three times daily for up to 4 weeks has been used (3334). More evidence is needed to rate cranberry for these uses.

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LIKELY SAFE ...when used orally or intravenously and appropriately. Calcium is safe when used in appropriate doses (7555,12928,12946,95817). However, excessive doses should be avoided. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: Age 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg; 19-50 years, 2500 mg; 51+ years, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stone, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients not to consume more than the recommended daily intake of 1000-1200 mg per day and to consider total calcium intake from both dietary and supplemental sources (17484). Also, advise patients taking calcium supplements to take calcium along with vitamin D (93533).

POSSIBLY UNSAFE ...when used orally in excessive doses. The National Academy of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 19-50 years, 2500 mg; 51 years and older, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients to not consume more than the recommended daily intake of 1000-1200 mg per day and to consider total calcium intake from both dietary and supplemental sources (17484). Also, advise patients taking calcium supplements to take calcium along with vitamin D (93533).

CHILDREN: LIKELY SAFE
when used orally and appropriately. Calcium is safe when used in appropriate doses (17506).

CHILDREN: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately (945,1586,3263,3264,17506). The World Health Organization (WHO) recommends prescribing oral calcium supplementation 1.5-2 grams daily during pregnancy to those with low dietary calcium intake to prevent pre-eclampsia (97347).

PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the same daily tolerable upper intake level (UL) for calcium according to age independent of pregnancy status: 9-18 years, 3000 mg; 19-50 years, 2500 mg (17506). Doses over these amounts might increase the risk of neonatal hypocalcemia-induced seizures possibly caused by transient neonatal hypoparathyroidism in the setting of excessive calcium supplementation during pregnancy, especially during the third trimester. Neonatal hypocalcemia is a risk factor for neonatal seizures (97345).

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LIKELY SAFE . .when used orally and appropriately. Cranberry juice up to 300 mL daily and cranberry extracts in doses up to 800 mg twice daily have been safely used in clinical trials (3333,3334,6758,6760,7008,8252,8253,8254,8995,11328) (16415,16720,17100,17126,17176,17210,17524,46379,46388,46389)(46390,46425,46439,46443,46465,46456,46466,46467,46469,46471)(46496,46499,90044,102847,111407).

CHILDREN: LIKELY SAFE
when cranberry juice is consumed in amounts commonly found in the diet (2811,6759,46441,46452,46470,111407). There is insufficient reliable information available about the safety of cranberry when used in medicinal amounts in children.

PREGNANCY AND LACTATION: LIKELY SAFE
when consumed in amounts commonly found in the diet. There is insufficient reliable information available about the safety of cranberry when used therapeutically during pregnancy or lactation; avoid using.

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ALUMINUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Calcium citrate might increase aluminum absorption and toxicity. Other types of calcium do not increase aluminum absorption.  Details Calcium citrate can increase the absorption of aluminum when taken with aluminum hydroxide. The increase in aluminum levels may become toxic, particularly in individuals with kidney disease (21631). However, the effect of calcium citrate on aluminum absorption is due to the citrate anion rather than calcium cation. Calcium acetate does not appear to increase aluminum absorption (93006).

BISPHOSPHONATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Calcium reduces the absorption of bisphosphonates.  Details Advise patients to take bisphosphonates at least 30 minutes before calcium, but preferably at a different time of day. Calcium supplements decrease absorption of bisphosphonates (12937).

CALCIPOTRIENE (Dovonex) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Taking calcipotriene with calcium might increase the risk for hypercalcemia.  Details Calcipotriene is a vitamin D analog used topically for psoriasis. It can be absorbed in sufficient amounts to cause systemic effects, including hypercalcemia (12938). Theoretically, combining calcipotriene with calcium supplements might increase the risk of hypercalcemia.

CALCIUM CHANNEL BLOCKERS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.  Details Intravenous calcium is used to decrease the effects of calcium channel blockers in the management of overdose. Intravenous calcium gluconate has been used before intravenous verapamil (Isoptin) to prevent or reduce the hypotensive effects without affecting the antiarrhythmic effects (6124). But there is no evidence that dietary or supplemental calcium when taken orally interacts with calcium channel blockers (12939,12947).

CEFTRIAXONE (Rocephin) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = D Co-administration of intravenous calcium and ceftriaxone can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys.  Details Avoid administering intravenous calcium in any form, such as parenteral nutrition or Lactated Ringers, within 48 hours of intravenous ceftriaxone. Case reports in neonates show that administering intravenous ceftriaxone and calcium can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys. In several cases, neonates have died as a result of this interaction (15794,21632). So far there are no reports in adults; however, there is still concern that this interaction might occur in adults.

DIGOXIN (Lanoxin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Using intravenous calcium with digoxin might increase the risk of fatal cardiac arrhythmias.  Details Hypercalcemia increases the risk of fatal cardiac arrhythmias with digoxin (12940). However, one retrospective analysis of clinical data suggests that intravenous calcium does not increase the risk of dysrhythmias or mortality in patients receiving digoxin (38960).

DILTIAZEM (Cardizem, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, calcium may reduce the therapeutic effects of diltiazem.  Details Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, calcium might increase this risk of hypercalcemia and reduce the effectiveness of diltiazem.

DOLUTEGRAVIR (Tivicay) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce levels of dolutegravir.  Details Advise patients to take dolutegravir either 2 hours before or 6 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium carbonate 1200 mg concomitantly with dolutegravir 50 mg reduces plasma levels of dolutegravir by almost 40%. Calcium appears to decrease levels of dolutegravir through chelation (93578).

ELVITEGRAVIR (Vitekta) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce levels of elvitegravir.  Details Advise patients to take elvitegravir either 2 hours before or 2 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium along with elvitegravir can reduce blood levels of elvitegravir through chelation (94166).

LEVOTHYROXINE (Synthroid, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce the absorption and effectiveness of levothyroxine.  Details Advise patients to take levothyroxine and calcium supplements at least 4 hours apart. Calcium reduces levothyroxine absorption, probably by forming insoluble complexes (5082). Calcium carbonate supplements reduce effectiveness of levothyroxine in patients with hypothyroidism (5081,5082,6137).

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use of calcium and lithium may increase this risk of hypercalcemia.  Details Clinical research suggests that long-term use of lithium may cause hypercalcemia in 10% to 60% of patients (38953). Theoretically, concomitant use of lithium and calcium supplements may further increase this risk.

QUINOLONE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce the absorption of quinolone antibiotics.  Details Advise patients to take oral quinolones at least 2 hours before or 4-6 hours after calcium supplements or calcium-fortified foods. Taking calcium at the same time as oral quinolones can reduce quinolone absorption. Calcium binds to quinolones in the gut (4412,10339,21638,38570).

RALTEGRAVIR (Isentress) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Calcium may reduce levels of raltegravir.  Details Pharmacokinetic research shows that taking a single dose of calcium carbonate 3000 mg along with raltegravir 400 mg twice daily modestly decreases the mean area under the curve of raltegravir, but the decrease does not necessitate a dose adjustment of raltegravir (94164). However, a case of elevated HIV-1 RNA levels and documented resistance to raltegravir has been reported for a patient taking calcium carbonate 1 gram three times daily plus vitamin D3 (cholecalciferol) 400 IU three times daily in combination with raltegravir 400 mg twice daily for 11 months. It is thought that calcium reduced raltegravir levels by chelation, leading to treatment failure (94165).

SOTALOL (Betapace) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Calcium seems to reduce the absorption of sotalol.  Details Advise patients to separate doses by at least 2 hours before or 4-6 hours after calcium. Calcium appears to reduce the absorption of sotalol, probably by forming insoluble complexes (10018).

TETRACYCLINE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Calcium seems to reduce the absorption of tetracycline antibiotics.  Details Advise patients to take oral tetracyclines at least 2 hours before, or 4-6 hours after calcium supplements. Taking calcium at the same time as oral tetracyclines can reduce tetracycline absorption. Calcium binds to tetracyclines in the gut (1843).

THIAZIDE DIURETICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.  Details Thiazides reduce calcium excretion by the kidneys (1902). Using thiazides along with moderately large amounts of calcium carbonate increases the risk of milk-alkali syndrome (hypercalcemia, metabolic alkalosis, renal failure). Patients may need to have their serum calcium levels and/or parathyroid function monitored regularly.

VERAPAMIL (Calan, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, calcium may reduce the therapeutic effects of verapamil.  Details Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, use of calcium supplements may increase this risk of hypercalcemia and reduce the effectiveness of verapamil.

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ATORVASTATIN (Lipitor) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, cranberry might increase levels and adverse effects of atorvastatin.  Details In one case report, a patient taking atorvastatin experienced upper back pain, rhabdomyolysis, and abnormal liver function after drinking cranberry juice 16 ounces daily for 2 weeks. Theoretically, this may have been caused by inhibition of cytochrome P450 3A4 (CYP3A4) enzymes by cranberry juice, as atorvastatin is a CYP3A4 substrate. Creatinine kinase and liver enzymes normalized within 2 weeks of stopping cranberry juice (90042). Patients taking atorvastatin should avoid large quantities of cranberry juice.

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = B Theoretically, cranberry might increase the levels and adverse effects of CYP2C9 substrates. However, research is conflicting.  Details There is contradictory evidence about the effect of cranberry on CYP2C9 enzymes. In vitro evidence suggests that flavonoids in cranberry inhibit CYP2C9 enzymes (10452,11115,90048). However, clinical research shows that cranberry juice does not significantly affect the levels, metabolism, or elimination of the CYP2C9 substrates flurbiprofen or diclofenac (11094,90048). Also, in patients stabilized on warfarin, drinking cranberry juice 250 mL daily for 7 days does not significantly increase the anticoagulant activity of warfarin, a CYP2C9 substrate (15374). Additional pharmacokinetic research shows that cranberry juice does not increase peak plasma concentrations or area under the concentration-time curve of warfarin (15393).

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, cranberry might increase the levels and adverse effects of CYP3A4 substrates.  Details A case of upper back pain, rhabdomyolysis, and abnormal liver function has been reported for a patient taking atorvastatin, a CYP3A4 substrate, in combination with cranberry juice 16 ounces daily for 2 weeks. Creatinine kinase and liver enzymes normalized within 2 weeks of stopping cranberry juice (90042). Also, animal research suggests that cranberry juice, administered intraduodenally 30 minutes prior to nifedipine, a CYP3A4 substrate, inhibits nifedipine metabolism and increases the area under the concentration-time curve by 1.6-fold compared to control (46420).

DICLOFENAC (Voltaren, others) Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = B Theoretically, cranberry might modestly increase the levels and adverse effects of diclofenac.  Details In vitro evidence suggests that cranberry juice inhibits diclofenac metabolism by human liver microsomes (90048). However, drinking cranberry juice does not seem to affect diclofenac metabolism in humans (90048).

NIFEDIPINE (Procardia) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, cranberry might increase the levels and adverse effects of nifedipine.  Details Animal research suggests that cranberry juice, administered intraduodenally 30 minutes prior to nifedipine treatment, inhibits nifedipine metabolism and increases the area under the concentration-time curve by 1.6-fold compared to control (46420). This interaction has not been reported in humans.

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, cranberry might increase the levels and adverse effects of warfarin. However, research is conflicting.  Details There is contradictory evidence about the effect of cranberry juice on warfarin. Case reports have linked cranberry juice consumption to increases in the international normalized ratio (INR) in patients taking warfarin, resulting in severe spontaneous bleeding and excessive postoperative bleeding (10452,12189,12668,21187,21188,21189,46378,46396,46411)(46415,90043). Daily consumption of cranberry sauce for one week has also been linked to an increase in INR in one case report (16816). In a small study in healthy young males, taking a high dose of 3 grams of cranberry juice concentrate capsules, equivalent to 57 grams of fruit daily, for 2 weeks produced a 30% increase in the area under the INR-time curve after a single 25-mg dose of warfarin (16416). However, 3 very small clinical studies in patients stabilized on warfarin reported that cranberry juice 250 mL once or twice daily for 7 days (27% cranberry juice or pure cranberry juice) or 240 mL once daily for 14 days does not significantly increase INR or affect plasma warfarin levels (15374,17124,90045). The reasons for these discrepant findings are unclear. It is possible that the form and dose of cranberry may play a role, as cranberry extracts and juices contain different constituents. Additionally, an in vitro study evaluating 5 different cranberry juices found varying effects, with only a cranberry concentrate, and not diluted cranberry juices, inhibiting CYP2C9. However, this concentrate did not inhibit CYP2C9 activity in humans (108062).

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General ...Orally and intravenously, calcium is well-tolerated when used appropriately.
Most Common Adverse Effects:
Orally: Belching, constipation, diarrhea, flatulence, and stomach upset.
Serious Adverse Effects (Rare):
Orally: Case reports have raised concerns about calciphylaxis and kidney stones.

Cardiovascular ...There has been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these results, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of CVD, CHD, or MI (93533,107231). Also, the association between calcium supplementation and CVD, CHD, or MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482). To minimize the possible risk of CVD, CHD, or MI, advise patients not to consume more than the recommended daily intake of 1000-1200 mg and to consider total calcium intake from both dietary and supplemental sources (17484). While dietary intake of calcium is preferred over supplemental intake, advise patients who require calcium supplements to take calcium along with vitamin D, as this combination does not appear to be associated with an increased risk of MI (93533).
Rarely, calcium intake can increase the risk of calciphylaxis, which usually occurs in patients with kidney failure. Calciphylaxis is the deposition of calcium phosphate in arterioles, which causes skin ulcers and skin necrosis. In a case report, a 64-year-old female with a history of neck fracture, sepsis, and ischemic colitis presented with painful leg ulcers due to calciphylaxis. She discontinued calcium and vitamin D supplementation and was treated with sodium thiosulfate and supportive care (95816).

Gastrointestinal ...Orally, calcium can cause belching, flatulence, nausea, gastrointestinal discomfort, and diarrhea (1824,1843,12950,38803). Although constipation is frequently cited as an adverse effect of calcium, there is no scientific substantiation of this side effect (1824,1843,1844,1845,12950,38978). Calcium carbonate has been reported to cause acid rebound, but this is controversial (12935,12936).

Oncologic ...There is some concern that very high doses of calcium might increase the risk of prostate cancer. Some epidemiological evidence suggests that consuming over 2000 mg/day of dietary calcium might increase the risk for prostate cancer (4825,12949). Additional research suggests that calcium intake over 1500 mg/day might increase the risk of advanced prostate cancer and prostate cancer mortality (14132). Consumption of dairy products has also been weakly linked to a small increase in prostate cancer risk (98894). However, contradictory research suggests no association between dietary intake of calcium and overall prostate cancer risk (14131,14132,104630). More evidence is needed to determine the effect of calcium, if any, on prostate cancer risk.

Renal ...Kidney stones have been reported in individuals taking calcium carbonate 1500 mg daily in combination with vitamin D 2000 IU daily for 4 years (93943).

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General ...Orally, cranberry seems to be well tolerated.
Most Common Adverse Effects:
Orally: Diarrhea and gastrointestinal discomfort.

Dermatologic ...Orally, skin redness and itching has been reported in one patient (46389).

Gastrointestinal ...In very large doses, for example 3-4 L per day of juice, cranberry can cause gastrointestinal upset and diarrhea, particularly in young children (46364). There are reports of abdominal and gastrointestinal discomfort after taking cranberry tablets, extracts, and juice in clinical trials (16720,46379,111407). Nausea, vomiting, and diarrhea have also been reported with consumption of lower doses of cranberry juice cocktail, 16 ounces per day, equivalent to about 4 ounces cranberry juice, for several weeks (16415).

Genitourinary ...Vulvovaginal candidiasis has been associated with ingestion of cranberry juice (46374). Clinical research suggests that ingestion of cranberry juice may be associated with vaginal itching and vaginal dryness (46471). One patient in clinical research stopped taking dried cranberry juice due to excessive urination (46437), and an isolated case of nocturia following ingestion of cranberry tablets has been reported (16720).

Hematologic ...Thrombocytopenia has been reported as an adverse event to cranberry juice (46459).

Other ...An isolated case of sensitive swollen nipples after taking cranberry tablets has been reported (16720).

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