Chitosan is made from the shells of shellfish and is a type of dietary fiber called an aminopolysaccharide (a combination of sugar and protein). Because of its positive charge, it has the ability to attract and bind to the negatively charged fatty acids in our diet. When consumed with fatty foods, chitosan has the ability to bind the fats and essentially block their absorption. Chitosan can absorb up to 4-6 times its weight in fat or cholesterol; therefore, for approximately every gram of chitosan consumed, about 4-6 g of fat can be blocked.

Most of the research on chitosan has been performed on animals and has shown chitosan to effectively block fat from digestion by binding to fats in the digestive system. However, the clinical data have given mixed results. Generally, it is accepted that chitosan works only if it is used in conjunction with a reduced-calorie diet, but clinical data are still needed to prove the best conditions for the use of chitosan and to back up claims of supplements.

In a small study conducted by Gades and Stern (2002), seven healthy males were fed a high-fat diet (>120 g/day) for 12 days. Chitosan (5.25 g/day) was administered on days 6-9 before meals and snacks, and charcoal markers were consumed on days 2, 6, and 10 to indicate the baseline and supplement periods. All feces were collected on days 2-12 and analyzed for fecal fat for the 4 baseline and 4 supplement days. Fecal fat content was found unchanged on the days of chitosan administration; therefore, no fat-blocking effect was observed.

Zahorska-Markiewicz et al. (2002) examined the use of chitosan in a complex treatment for obesity involving 6 months in which subjects followed a low-calorie diet (1,000 kcal/day), chitosan orplacebo supplementation, and modifications in physical activity and behavior, supported by 2-hour group meetings with a physician, psychologist, and dietitian 2 times weekly. The chitosan (750 mg of pure chitosan called Chitinin, 2 tablets 3 times daily before each main meal) was studied using a double blind, placebo controlled, randomized design. Significantly greater body weight loss was found in the chitosan group (15.9 kg) versus the placebo group (10.9 kg), and also significantly lower systolic and diastolic blood pressure readings were observed in the chitosan group. No difference in cholesterol (total or low-density lipoprotein [LDL]) levels between groups and no adverse effects were noted.

The fat-blocking effects of prescription orlistat versus chitosan supplementation were compared in a randomized, open-label, two-period, sequential study design. Twelve healthy volunteers followed a standardized diet for the 21-day study and were subjected to a 7-day initial run-in diet. The groups were randomized and given either orlistat (120 mg) or chitosan (890 mg) 3 times daily for 7 days, and then the groups were crossed over for another 7 days of treatment. Fecal fat excretion was measured daily and found to be significantly increased with orlistat and not significantly changed by chitosan (Guerciolini et al., 2001).

In a randomized, double-blind, placebo-controlled study in obese, hypercholesterolemic subjects without dietary restriction, chitosan (as Asorbitol, a commercial chitosan product) or placebo was administered at the dosage of 250 mg 3 times daily. Sixty-eight subjects completed the study, and weight, body mass index, lean body mass, waist, hip, blood pressure, fasting lipids, and insulin levels were taken at the beginning and at weeks 4 and 6 of the study. The only change in the measured parameters was an increase in high-density lipoprotein (HDL) cholesterol in the chitosan group versus a decrease in the placebo group (Ho et al., 2001).

Pittler (1999) examined the use of chitosan for weight loss in a randomized, double-blind, placebo-controlled clinical trial. Thirty-four overweight people were given either a placebo or chitosan (2 g/ day) for 28 days. The participants were instructed to maintain their normal diet and to document the types and amounts of foods they consumed. At the end of the study, no significant changes in weight were observed between the treatment and placebo groups, and no changes in the levels of serum cholesterol, body mass index, triglycerides, ft carotene, and vitamins A, D, and E were observed. No serious adverse effects were noted, and the authors concluded that unless accompanied by other dietary alterations, chitosan does not reduce body weight in overweight people.

In a randomized, double-blind, placebo-controlled study of 86 obese people, the effect of a chitosan fiber along with a low-calorie diet was measured on weight loss and lipid-lowering parameters. The chitosan fiber product (Somagril) studied was a mixture of chitosan, guar, ascorbic acid, and other micromitrients, and the treatment group was given 4 tablets/day (unspecified amount of chitosan) for 4 weeks. The results for the chitosan group (C) and the placebo group (P) indicated statistically greater effect in the reductions of all parameters. Additionally, HDL increased 11.8% in the C group and 4.6% in the P group. No statistically significant side effects were noted in either group. The authors concluded that the chitosan fiber product plus a low-calorie diet is useful in treating obese patients, with benefits including reduced levels of hypertension and hyperlipoproteinemia (Sciutto and Colombo, 1995).

Giustina and Ventura (1995) studied the combination of a chitosan dietary fiber product (Somagril, 4 tablets/day) and a low-calorie diet for its effects on weight reduction in a randomized, double-blind, placebo-controlled study of 100 obese subjects. Statistically significant reductions in the chitosan group (C) and the placebo group (P) of body weight (83.6 kg C and 76.3 kg P), overweight percentage (from 17.2% to 7.3% C and 16.3% to 12.4% P), arterial systolic pressure (from 145.3 to 135 mm Hg C and 146.0 to 142.9 mm Hg P), arterial diastolic pressure (92.6 mm Hg to 84.2 C and 92.5 to 90.0 P), and respiratory rate (27.6/ min to 21.2/min C and 28.1/min to 26.3/min P) were measured. No statistically significant side effects between the two groups were noted, and any adverse effects were mild and transient. The authors concluded that the chitosan fiber product plus a low-calorie diet is useful in the treatment of obesity better than a low-calorie diet alone and with the side benefits of ameliorating the secondary disorders of hypertension or dyspnea.

Author Bio: Georgiy Kharchenko with American Weight Loss Group LLC: Fitness Trainer, Ephedra Products, Natural Weight Loss Pills, Phentramin D Tablets

Category: Medicines and Remedies
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