A SPECIAL ARTICLE Psyllium versus Guar Gum: Facts and Comparisons by T.S. Dharmarajan INTRODUCTION stool mass, which floats in the toilet rather than sink- ietary fiber is a term that denotes components of ing while the unfermented gel from psyllium functions plant origin that are resistant to digestion by gas- as an emollient and lubricant. Dtrointestinal enzymes in humans. Based on its Guar gum is extracted from the seeds of the shrub solubility in water, fiber may be classified as soluble Cyamopsis tetragonolobus wherein it acts as a food or insoluble. Soluble fiber, the basis for discussion and water store. The annual plant, which flourishes in here, is a plant ingredient that stores water. Besides India, Pakistan and the West, is drought resistant and storing water, its properties include the ability to fer- thrives in sandy soil. Guar gum is an economical ment and to increase viscosity (1,2). thickener, emulsifier and stabilizer that hydrates Psyllium and guar gum are two forms of soluble rapidly in cold and hot water to give solutions high fiber that make an interesting comparison. Psyllium, viscosity. It retards ice crystal growth and is resistant mainly cultivated in Iran and India, is used in the man- to oils and solvents. Milk reactivity is in question. agement of several medical disorders and also as an Guar gum is approved for use in foods, pharmaceuti- herbal remedy. Psyllium is a member of the plant fam- cals and cosmetics. In the food industry, examples ily Plantaginaceae. Its common names include flea include bakeries and dairies. It is a common ingredient seed and ispaghula while the botanical names are for dressings and sauces and as a stabilizer for drinks Plantago ovato and Plantago ispaghula. Psyllium and juices. Guar gum serves as a thickener for sham- seeds contain up to 30% mucilage; swelling of the poos and toothpastes. It is also used in the textile and husk occurs in contact with water, resulting in a gelati- paper industries (Table 1). nous mass and an increase in bulk that keeps feces hydrated and soft (3). Psyllium husks are pure dietary BENEFITS IN HEALTH AND DISEASE fiber that is mainly composed of hemicellulose. This component of fiber is not digested in the small intes- Hyperlipidemia tine, but instead it is broken down in the colon where In numerous studies, psyllium has been found to be it acts as a food source for the intestinal flora. The bac- beneficial in lowering total and LDL (“bad”) choles- terial mass and water contribute to an increase in stool terol (4). However, HDL (“good”) cholesterol does not weight. The husks absorb water to form a soft bulky appear to be affected (5). The benefits of psyllium in hyperlipidemia are secondary to its soluble component. T.S. Dharmarajan, M.D., FACP, AGSF, Chief, Divi- In a meta-analysis of 8 controlled trials, psyllium sup- sion of Geriatrics, Director, Geriatric Medicine Fellow- plements caused significant reductions in total and LDL ship Program, Our Lady of Mercy Medical Center, cholesterol in subjects on a low-fat diet (6). Other solu- Bronx, New York, Professor of Medicine, New York ble fibers, such as guar gum (besides pectin and oat Medical College, Valhalla, NY. bran), also decrease total and LDL cholesterol. How- 72 PRACTICAL GASTROENTEROLOGY • FEBRUARY 2005 Psyllium Versus Guar Gum A SPECIAL ARTICLE ever, practical use of many of the latter Table 1 forms of fiber is limited by the lack of Properties of Psyllium and Guar Gum palatable preparations (7). In a study in rats comparing 10 different fibers, psyl- Property Psyllium Guar Gum lium use was associated with the lowest serum cholesterol levels (8). The Food Botanical name P. ovato, P. ispaghula C. tetragonolobus and Drug Administration has authorized Structure Non starch polysaccharide Non starch polysaccharide the use of “the association of psyllium Solubility Soluble Soluble and a reduced risk of coronary heart dis- ease” on health labels. This health claim Component Mucilage, hemicellulose Gum was attributed to a lowering of choles- Thickening effect Effective Very effective terol levels, based on the assumption Palatability Several choices Limited that 4 servings of dietary fiber per day would reduce cardiovascular risk (9). Gas, bloating Less problematic More problematic Diabetes also been demonstrated is the regulation of stool fre- In type 2 diabetes, addition of psyllium to dietary mea- quency in irritable bowel syndrome. Aside from these sures has been shown to improve glycemic control (4). examples of relief in transit disorders, in ventilator- The benefit appears to result from a slowing of glucose dependent septic patients, soluble fiber in the form absorption from the small intestine. Psyllium treatment of guar gum added to enteral feeding reduced the should be individualized for maximum effect (10). In a incidence of diarrhea (16). The addition of guar gum study comparing ispaghula husk (psyllium) with guar (7 g daily) to a standard tube feeding formula gum, mean serum postprandial insulin levels decreased stool frequency and helped normalize stool decreased for both, but the area under the glucose flora (17). The relief of constipation and resultant curve was reduced significantly for psyllium but not long-term regular bowel habits with soft stools from for guar gum (11). the use of fiber provides relief to individuals suffering from hemorrhoids. Constipation and Other Gastrointestinal Transit Disorders Hunger, Food Intake and Weight Loss Many studies have revealed the benefit of psyllium in Psyllium reduces the feeling of hunger and thereby alleviating constipation by speeding the transit of stool energy intake. The mechanism of action may entail through the intestines. Its use is standard practice for increasing the time for intestinal absorption and flat- constipation. Psyllium increases stool mass more than tening of glucose, insulin and triglyceride curves with- common fiber sources such as oat bran and wheat bran out altering gastric emptying for solids or liquids (18). (12,13). A comparison of psyllium as ispaghula husk Hence, it is conceivable that psyllium may help in with other laxatives revealed that ispaghula use was weight loss, inducing a feeling of stomach fullness associated with a higher percentage of well-formed without providing calories. The addition of guar gum and less hard stools, as well as less soiling, diarrhea to meals has also been shown to prevent an increase in and abdominal discomfort (14). As a bulk-forming appetite, hunger and desire to eat (19). agent, psyllium also helps manage mild diarrhea by providing a stool firmer that slows transit time. In ulcerative colitis, psyllium seeds (10 grams twice Blood Pressure daily) were as effective as mesalamine in maintaining Soluble fiber administered as psyllium (12 g/d) remission in one trial (15). Another benefit that has reduced 24-hour and awake systolic blood pressure. PRACTICAL GASTROENTEROLOGY • FEBRUARY 2005 73 Psyllium Versus Guar Gum A SPECIAL ARTICLE Table 2 ADMINISTRATION Psyllium and Guar Gum in Health Care Fiber is an important dietary ingredi- ent, but the precise dietary require- Disorder Psyllium Guar Gum ments for protective benefits are not Hypercholesterolemia Lowers LDLC, TC Lowers LDLC, TC clear. In general, it is advisable to con- sume fiber from natural sources before Diabetes Significant benefit Significant benefit resorting to supplements. The Ameri- Constipation Significant benefit Some benefit can Dietetic Association recommends Diarrhea Some benefit Some benefit the consumption of 20 to 35 grams of fiber per day. A combination of solu- Irritable bowel syndrome Some benefit Role not clear ble and insoluble fiber is recom- Ulcerative colitis Some benefit Role not clear mended (1,2). Where the dietary intake of fiber is inadequate, commer- Weight loss May be helpful May be helpful cial preparations supplement fiber Blood pressure Beneficial in Benefit in post-prandial intake to match the recommended hypertension? hypotension? amounts. Standard forms of psyllium are This finding may have implications in long-term treat- available in dry seed and husk form. Psyllium is taken ment of hypertension (20). In quite the opposite set- one to three times a day with plenty of water a half ting, through a slowing of gastric emptying and glu- hour before or at least an hour after meals. Husks can cose absorption, guar gum reduced the magnitude of a be added to soups or sauces as a thickener. Psyllium drop in blood pressure after an oral glucose load. This should be taken with a full 8 oz glass of water, and it finding may provide a novel approach to the manage- ment of post-prandial hypotension (21). (continued on page 76) Table 3 Miscellaneous Considerations A Comparison of Two Forms of Soluble Fiber In one study, the consumption of fiber (as P. ovata) has been associated with a reduced risk Konsyl Benefiber of colon cancer (22). However, the data from Ingredient Psyllium Hydrolyzed guar gum numerous trials evaluating the relationship Serving Size 1 teaspoon 1 tablespoon between dietary fiber and colorectal cancer are at best conflicting (1,23). Fiber, particu- Serving Size (grams) 6 g/teaspoon 4 g/tablespoon larly the insoluble component, has been asso- Fiber (g/serving) 5 grams 3 grams ciated with a decreased risk of diverticular disease. In patients in whom adequate intake Calories 3 per serving 16 per serving of insoluble fiber is not possible, preparations Sodium 4.1 mg 15 mg such as psyllium may be helpful. Potassium 42 mg 15 mg Psyllium use is not habit forming. As a pure fiber, the husks contain only trace calo- Calcium 48 mg none ries, vitamins and minerals. Unlike wheat Carbohydrate 0.05 g 4.0 g bran and some other fiber, excessive bloating Protein 5.3% none attributable to gas formation is less likely to occur with psyllium. Gastrointestinal side Fat 2.7% none effects appear to be more common with guar Sugars none none gum (2) (Table 2).