Glucomannan by Wonder Laboratories

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).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• 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.

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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.

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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.

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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).

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