Scientific Name(s): Cyamopsis tetragonolobus (L.) Taub. synonymous with C. psoralioides DC. Family: Fabaceae (beans)
Common Name(s): Guar , guar flour , jaguar gum
Guar gum is a food additive shown to reduce serum cholesterol. It appears to have positive effects on blood glucose. Do not use guar gum to promote weight loss.
Guar gum has been administered in amounts from 7.5 to 21 g daily in clinical trials for weight loss.
Contraindications have not yet been identified.
Information regarding safety and efficacy in pregnancy and lactation is lacking.
Large amounts of guar gum (10 g or more daily) may decrease metformin serum concentrations and should be avoided.
Guar gum may cause GI obstruction. Use guar gum cautiously in diabetic patients. Flatulence and other symptoms of GI distress are common during initial use.
Research reveals little or no information regarding toxicology with the use of guar gum.
The guar plant is a small nitrogen-fixing annual that bears pods, each containing a number of seeds. Native to tropical Asia, the plant grows throughout India and Pakistan and has been grown in the southern US since the beginning of the 20th century. 1
Guar gum is a dietary fiber obtained from the endosperm of the Indian cluster bean. The endosperm can account for more than 40% of the seed weight and is separated and ground to form commercial guar gum.
Guar gum has been used for centuries as a thickening agent for foods and pharmaceuticals. It continues to find extensive use for these applications as well as the paper, textile, and oil drilling industries.
Guar is a galactomannan polysaccharide that forms a viscous gel when placed in contact with water. It forms solutions that range from slightly acidic to neutral pH. Even at low concentrations (1% to 2%) guar gum forms gels in water. The viscosity of these gels is generally unaffected by the pH of the solution.
Food grade guar gum contains ≈ 80% guaran (a galactomannan composed of D-mannose and D-galactose units) with an average molecular weight of 220 kDa. However, guar gum is not a uniform product and its viscosity may vary in proportion to the degree of galactomannan cross-linking.
Because of this physical composition, guar gum-based matrix tablets are currently being evaluated as a method of administering sustained-release drugs including diltiazem, 2 , 3 and for colonic drug delivery of corticosteroids to patients with inflammatory bowel disease. 4
Uses and PharmacologyHyperlipidemia
Research reveals no animal data regarding the use of guar gum for hyperlipidemia.Clinical data
Guar gum has been shown to have positive effects on cholesterol at doses ranging from 12 to 15 g/day. Most short-term studies (< 1 year) in patients with mild to moderate hypercholesterolemia have demonstrated a decrease in serum total cholesterol levels ≈ 6.5% to 15% and in low density lipoprotein-cholesterol (LDL cholesterol) by between 10.5% and 25%, without any effect on triglycerides or high density lipoprotein-cholesterol (HDL cholesterol) levels. 5 , 6 , 7 , 8 , 9 A long-term study in 40 patients illustrated that the effects of guar gum on total cholesterol and LDL cholesterol are sustained with continued use over a period of 24 months. 10 A comprehensive review of the lipid-lowering effects of guar gum described a general hypothesis for the mechanism of this action: Guar reduces cholesterol absorption and increases bile excretion leading to increased hepatic turnover of cholesterol. It has been suggested that the effects of guar on LDL cholesterol metabolism are similar to those of the bile-sequestering agents. 11
Guar gum also has been used as an adjunct to more conventional lipid-lowering therapy. Coadministration with lovastatin resulted in a larger decrease in total cholesterol levels (44%) compared with lovastatin alone (34%) after 18 weeks of treatment. 12 Guar gum has an unpleasant flavor. Placebo-controlled trials have used a number of methods in an attempt to mask this; using uncoated granules, 13 powders, crispbreads, and other flavored formulas. 14Diabetes mellitus
The ability of guar to alter viscosity 15 and thus affect GI transit results in delayed absorption of glucose and may contribute to its hypoglycemic activity.Animal data
Research reveals no animal data regarding the use of guar gum for diabetes mellitus.Clinical data
Guar reduces postprandial glucose and insulin levels in healthy subjects 15 and patients with type 2 diabetes mellitus. 16 , 17 , 18 , 19 , 20 , 21 No reduction in plasma C-peptide levels was observed, suggesting that guar gum attenuates the insulin concentration in peripheral venous blood by increasing the hepatic extraction of insulin. 21 These effects on glucose and insulin seem to be most pronounced when large amounts of guar gum are added to the diet, and when the fiber is administered with the glucose or food. 22 However, when dietary fats and proteins are not adequately controlled in the diabetic diet, the addition of guar has been shown to have little effect on postprandial glucose or C-peptide responses. 23GI motility
Preparations containing guar gum have been used extensively to promote normal GI motility and to maintain fecal bulk. 24 Guar preparations may delay gastric emptying time or GI transit, but these effects seem to be related to the type of meal and diet.Animal data
Research reveals no animal data regarding the use of guar gum for GI motility.Clinical data
Oral rehydration solution, supplemented with guar gum, may reduce the duration of diarrhea in young children. 25 Also, the addition of enzymatically modified guar gum to enteral formulas has been shown to increase GI transit time, increase fecal nitrogen excretion, 26 and reduce diarrhea. 27 This is achieved without any effects on normal absorption of glucose, amino acids, or fat, or any adverse effects on hematological, hepatic, or renal function. 28Weight loss
Because bulk-forming fibers may impart a “feeling of fullness,” they have been used to help curb appetite.Animal data
Research reveals no animal data regarding the use of guar gum for weight loss.Clinical data
One small study has suggested that guar gum may have a more profound effect on satiety when added to a meal rich in fat than when added to a low-fat meal. 29 A meta-analysis presented the combined results of 20 randomized controlled trials in which guar gum (average daily dose, 9 to 30 g) was compared with placebo. 30 It was shown conclusively that guar gum is not efficacious for reducing body weight. Additionally, a number of studies using a partially hydrolyzed form of guar gum, which has no viscosity or bulking effect, have found no effect on appetite 31 or weight maintenance. 32 Although evidence for the effectiveness of fiber products as appetite suppressants is lacking, they remain popular ingredients in OTC weight loss preparations.Blood pressure
Guar gum has been reported to have varied effects on blood pressure.Animal data
Research reveals no animal data regarding the use of guar gum for blood pressure.Clinical data
One small study of 10 elderly subjects showed a reduction in postprandial hypotension (defined as a decrease in systolic blood pressure > 20 mm Hg occurring within 2 hours of the end of a meal). 33 Conversely, guar supplementation for 2 weeks was shown to reduce blood pressure by 9% in moderately overweight men. 34Intrahepatic cholestasis and pruritus in pregnancy
Research reveals no animal data regarding the use of guar gum for intrahepatic cholestasis and pruritus in pregnancy.Clinical data
In 2 double-blind studies, guar gum diminished or prevented worsening of pruritus in 96 pregnant women with intrahepatic cholestasis. This outcome is related to bile acid concentration, which remained unchanged in the guar gum-treated patients but increased in the placebo recipients. 35 , 36 The authors suggest that guar gum is a safe alternative and possible treatment option in these patients.
Guar gum has been administered in amounts from 7.5 to 21 g daily in clinical trials for weight loss. 37
Information regarding safety and efficacy in pregnancy and lactation is lacking.
Guar gum reduces the absorption of metformin, which may decrease the hypoglycemic effect. 38 The effect of ingestion of 10 g of guar gum on a single 1700 mg dose of metformin was studied in 6 healthy subjects. 38 Guar gum decreased metformin serum levels between 1.5 and 5 hours after taking guar gum. The metformin area under the curve was decreased 39% and the absorption rate was decreased over the first 6 hours following coadministration of guar gum.
In the colon, guar gum is fermented to short-chain fatty acids. Both guar and its resultant by-products do not appear to be absorbed by the gut. The most common adverse effects are GI, including GI pain, nausea, diarrhea, and flatulence. Approximately 50% of those taking guar experience flatulence; this usually occurs early in treatment and resolves with continued use. A dose of ≈ 3 g 3 times/day, not to exceed 15 g/day, can minimize GI effects. 39
Guar gum may affect the absorption of coadministered drugs. Slowed absorption of digoxin, acetaminophen, and bumetanide, and decreased absorption of metformin, penicillin V, and some formulations of glyburide have been reported. 40 Bezafibrate, glipizide, and glyburide 41 are generally unaffected by coadministration. 5
Guar gum in a weight-loss product was implicated as causing esophageal obstruction in a patient who exceeded the recommended dosage. 42 In a review, 18 cases of esophageal obstruction, 7 cases of small bowel obstruction, and possibly 1 death were associated with the use of Cal-Ban 3000 , a guar gum-containing diet pill. 43 The water-retaining capacity of the gum permits it to swell 10- to 20-fold and may lead to luminal obstruction, particularly when an anatomic predisposition exists. Take guar with large amounts of liquid.
Occupational asthma has been observed among those working with guar gum. 44 Because of its potential to affect glycemic control, guar gum should be used cautiously in diabetic patients. Guar gum is not teratogenic and does not affect reproduction in rats. 45
Research reveals little or no information regarding toxicology with the use of guar gum.
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