Guar Gum

Scientific Name(s): Cyamopsis tetragonolobus (L.) Taub. synonymous with C. psoralioides DC. Family: Fabaceae (beans)

Common Name(s): Guar , guar flour , jaguar gum

Uses

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.

Dosing

Guar gum has been administered in amounts from 7.5 to 21 g daily in clinical trials for weight loss.

Contraindications

Contraindications have not yet been identified.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

Large amounts of guar gum (10 g or more daily) may decrease metformin serum concentrations and should be avoided.

Adverse Reactions

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.

Toxicology

Research reveals little or no information regarding toxicology with the use of guar gum.

Botany

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.

History

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.

Chemistry

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 Pharmacology

Hyperlipidemia
Animal data

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. 14

Diabetes 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. 23

GI 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. 28

Weight 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. 34

Intrahepatic cholestasis and pruritus in pregnancy
Animal data

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.

Dosage

Guar gum has been administered in amounts from 7.5 to 21 g daily in clinical trials for weight loss. 37

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

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.

Adverse Reactions

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

Toxicology

Research reveals little or no information regarding toxicology with the use of guar gum.

Bibliography

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10. Salenius JP, Harju E, Jokela H, Riekkinen H, Silvasti M. Long term effects of guar gum on lipid metabolism after carotid endarterectomy. BMJ . 1995;310:95-96.
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12. Uusitupa MI, Miettinen TA, Happonen P, Ebeling T, Turtola H, Voutilainen E, Pyorala K. Lathosterol and other noncholesterol sterols during treatment of hypercholesterolemia with lovastatin alone and with cholestyramine or guar gum. Arterioscler Thromb . 1992;12:807-813.
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14. Jenkins DJ, Leeds AR, Slavin B, Mann J, Jepson EM. Dietary fiber and blood lipids: reduction of serum cholesterol in type II hyperlipidemia by guar gum. Am J Clin Nutr . 1979;32:16-18.
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16. Smith U, Holm G. Effect of a modified guar gum preparation on glucose and lipid levels in diabetics and healthy volunteers. Atherosclerosis . 1982;45:1-10.
17. Aro A, Uusitupa M, Voutilainen E, Hersio K, Korhonen T, Siitonen O. Improved diabetic control and hypocholesterolaemic effect induced by long-term dietary supplementation with guar gum in type 2 (insulin-independent) diabetes. Diabetologia . 1981;21:29-33.
18. Lakhdar A, et al. Fibre and patients with diabetes [letter]. BMJ . 1988;296:1471.
19. Kirsten R, Heintz B, Nelson K, Oremek G, Speck U. Influence of two guar preparations on glycosylated hemoglobin, total cholesterol and triglycerides in patients with diabetes mellitus. Int J Clin Pharmacol Ther Toxicol . 1992;30:582-586.
20. Landin K, Holm G, Tengborn L, Smith U. Guar gum improves insulin sensitivity, blood lipids, blood pressure, and fibrinolysis in healthy men. Am J Clin Nutr . 1992;56:1061-1065.
21. Gatenby SJ, Ellis PR, Morgan LM, Judd PA. Effect of partially depolymerized guar gum on acute metabolic variables in patients with non-insulin-dependent diabetes. Diabet Med . 1996;13:358-364.
22. Nuttall FQ. Dietary fiber in the management of diabetes. Diabetes . 1993;42:503-508.
23. Sels JP, De Bruin H, Camps MH, et al. Absence of guar efficacy in complex spaghetti meals on postprandial glucose and C-peptide levels in healthy control and non-insulin-dependent diabetes mellitus subjects. Horm Metab Res Suppl . 1992;26:52-58.
24. Rajala SA, Salminen SJ, Seppanen JH, Vapaatalo H. Treatment of chronic constipation with lactitol sweetened yoghurt supplemented with guar gum and wheat bran in elderly hospital in-patients. Compr Gerontol . 1988;2:83-86.
25. Alam NH, Meier R, Schneider H, et al. Partially hydrolyzed guar gum-supplemented oral rehydration solution in the treatment of acute diarrhea in children. J Pediatr Gastroenterol Nutr . 2000;31:503-507.
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27. Homann HH, Kemen M, Fuessenich C, Senkal M, Zumtobel V. Reduction in diarrhea incidence by soluble fiber in patients receiving total or supplemental enteral nutrition. J Parenter Enteral Nutr . 1994;18:486-490.
28. Alam NH, Meier R, Rausch T, et al. Effects of a partially hydrolyzed guar gum on intestinal absorption of carbohydrate, protein and fat: a double-blind controlled study in volunteers. Clin Nutr . 1998;17:125-129.
29. French SJ, Read NW. Effect of guar gum on hunger and satiety after meals of differing fat content: relationship with gastric emptying. Am J Clin Nutr . 1994;59:87-91.
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33. Jones KL, MacIntosh C, Su Y-C, et al. Guar gum reduces postprandial hypotension in older people. J Am Geriatr Soc . 2001;49:162-167.
34. Krotkiewski M. Effect of guar gum on the arterial blood pressure. Acta Med Scand . 1987;222:43-49.
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36. Gylling H, Riikonen S, Nikkilä K, Savonius H, Miettinen TA. Oral guar gum treatment of intrahepatic cholestasis and pruritus in pregnant women: effects on serum cholestanol and other non-cholesterol sterols. Eur J Clin Invest . 1998;28:359-363.
37. Gin H, et al. the influence of guar gum on absorption of metformin from the gut in healthy volunteers. Horm Metab Res 1989;21:81-83.
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39. Tuomilehto J, Silvasti M, Manninen V, Uusitupa M, Aro A. Guar gum and gemfibrozil—an effective combination in the treatment of hypercholesterolaemia. Atherosclerosis . 1989;76:71-77.
40. Fugh-Berman A. Herb-drug interactions. Lancet . 2000;355:134-138.
41. Uusitupa M, Sodervik H, Silvasti M, Karttunen P. Effects of a gel forming dietary fiber, guar gum, on the absorption of glibenclamide and metabolic control and serum lipids in patients with non-insulin-dependent (type 2) diabetes. Int J Clin Pharmacol Ther Toxicol . 1990;28:153-157.
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43. Lewis JH. Esophageal and small bowel obstruction from guar gum-containing “diet pills”: analysis of 26 cases reported to the Food and Drug Administration. Am J Gastroenterol . 1992;87:1424-1428.
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45. Collins TF, Welsh JJ, Black TN, Graham SL, O'Donnell MW Jr. Study of the teratogenic potential of guar gum. Food Chem Toxicol . 1987;25:807-814.

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