About Herbs

Bottom Line: Chitosan has never been shown to work on its own (without diet and exercise) for weight loss or cholesterol reduction. Claims of increased fat excretion are not true, but it may reduce the absorption of important nutrients.

Chitosan's main ingredient is chitin, an extract from the exoskeleton of crustaceans (e.g., shrimp, lobster, and clams). Chitin is indigestible by the human GI tract, and therefore is completely eliminated in the feces. The marketers of chitin-containing weight loss products claim that chitin binds to fat and cholesterol in the intestine, preventing them from being absorbed. However, in an evaluation of people before and after using chitosan, it was found that chitosan did not result in increased levels of fat excreted in their feces. On the downside, chitin may reduce the absorption of other important nutrients, such as nitrogen, vitamins, and calcium. Application of chitosan to wounds has been shown to aid in wound healing; scientists think it may enhance a number of the steps in the formation of new tissue.

Weight loss:
The effect of chitosan on weight loss was assessed in 30 overweight individuals. Subjects maintained their current diet with the addition of either 1000 mg of chitosan or a similar placebo twice daily. At two and four weeks into the study, those taking chitosan and those taking placebo showed similar changes in weight, total cholesterol, triglycerides, or quality of life, indicating that chitosan does not cause weight loss when used without dietary changes. The researchers found that the over-the-counter product used in this study contained only 60% of the labeled chitosan content.

A study examined the claim that chitosan (Fat Trapper®) increases the excretion of fat in the feces and thereby promotes weight loss. Twelve healthy volunteers ate normally and three times a day took either 890 mg of chitosan or 120 mg of orlistat (Xenical®, a prescription drug that increases fat excretion). After a week, the volunteers switched treatments. Their feces were collected on days four through seven and were analyzed for fat content. Compared to before treatment, chitosan did not increase fat excretion, while orlistat did. This suggests that marketer's claims that chitosan binds fat and helps to eliminate it from the body may not be true.

Hemodialysis side effects:
Patients undergoing hemodialysis three times a week took part in a study of chitosan's effects on anemia and cholesterol reduction. Patients took 1400 mg of chitosan or a similar placebo pill three times a day for 12 weeks. The patients taking chitosan showed an increase in blood hemoglobin levels from 5.8 g/dL to 6.8 g/dL, while these levels did not really change in patients taking placebo. The researchers are unsure how chitosan exerts this effect and do not mention whether the patients used other therapies to treat anemia. A significant reduction in total cholesterol was also noted for patients taking chitosan. These results may not apply to patients not undergoing hemodialysis.

Wound healing:
In 20 patients who were receiving skin grafts, chitosan was applied to half of the donor site so that researchers could monitor its effects on wound healing. The other half was covered with either Kaltostat® or Mepitel® conventional dressing. Chitosan had a similar healing time compared to the Kaltostat dressing, but a significantly shorter healing time compared to the Mepitel dressing. None of the patients developed donor site infections or adverse reactions to chitosan. These results may not apply to other cases of wound healing.

High cholesterol:
The effect of chitosan on high cholesterol was studied in 33 patients with type II diabetes who had been unsuccessful in reducing their cholesterol with diet alone. Patients received either 450 mg of chitosan or a similar placebo pill three times a day for 8 weeks, then crossed over to the opposite treatment for another 8 weeks. While taking chitosan, patients showed a significant reduction in total cholesterol and LDL ("bad") cholesterol compared to when taking the placebo pill. These results may not apply to non-diabetics.

Chitosan's ability to increase fat excretion is questionable. Any attempt at weight loss or cholesterol reduction should include dietary modifications and/or exercise.

Deacetylated chitin bipolymer

Chitosan, kitosan, chitin

Fat Trapper™, Fat Trapper Plus™, Fat Absorb™, Fat Blocker™

Chitin is extracted from the exoskeleton of crustaceans, including shrimp, lobster, and clams. A derivative of chitin, chitosan is used as an excipient in pharmaceutical formulations for weight loss, hyperlipidemia, and wound healing. It is also made into an edible film to protect food from spoilage ⁽⁸⁾. Although it is said to bind fat in the gut, several clinical trials found no increase in fecal excretion of fat or weight loss as compared to placebo ^{(4) (5) (9)}. Chitosan may lower low-density lipoprotein (LDL) cholesterol, although an optimal dose and long-term efficacy are not yet established ⁽²⁾. Limited clinical data are available regarding efficacy for anemia of chronic renal failure, although chitosan did show benefit in a small randomized study ⁽⁶⁾. Reported adverse events include constipation and gastrointestinal distress ⁽⁴⁾. Patients allergic to shellfish should not use this supplement. Pregnant women should not consume due to binding of fat soluble vitamins (ADEK) and calcium.

The exact mechanism of action is not known. Following oral administration, chitosan forms a positively charged gel matrix in stomach acid able to bind bile acids, nitrogen metabolites, phospholipids, unesterified cholesterol, fat-soluble vitamins, and calcium ⁽²⁾. Increased elimination of fat has not been demonstrated ⁽⁵⁾. Topical application enhances wound healing by stimulation of granulation tissue. Possible mechanisms of action include formation of a gel-like fibronectin matrix that facilitates inward epithelial cell migration and the formation of heparin-chitosan complexes that ultimately activates growth factors that bind to stabilized heparin ⁽³⁾.

Not absorbed systemically.

In April 2000, the Federal Trade Commission issued a court order against Enforma Natural Products, Inc., manufacturers of Fat Trapper and Fat Trapper Plus, for making unsubstantiated and deceptive claims about the health benefits of these products. The order prohibits Enforma from using the name "Fat Trapper" and requires them to disclose in advertising that dieting and/or exercise are required to lose weight. FTC report available at: http://www.ftc.gov/opa/2002/07/enforma.htm.

Patients with shellfish allergy should not use chitosan.
Pregnant women should not consume chitosan due to a possible reduction in calcium and vitamin D absorption.

Reported: Constipation, flatulence, and GI distress symptoms
⁽⁴⁾

Vitamins A, D, E, and K: Chitosan may bind fat-soluble vitamins and decrease absorption.
⁽¹⁾

Total cholesterol, LDL

Stone CA, et al. Healing at skin graft donor sites dressed with chitosan. Br J Plast Surg 2000;53:601-6.
Prospective evaluation of 20 patients receiving skin grafts from either thigh or forearm. Patients served as their own control. Half of the donor site was dressed with conventional material and the other half with chitosan. Time to healing was primary endpoint. No donor site infections or adverse reactions were noted. Chitosan had a similar healing time to Kaltostat control dressing, but a significantly shorter healing time compared to Mepitel control dressing. Observational data suggest chitosan improved re-epithelialization, nerve, and capillary regeneration, but further research is needed.

Guerciolini R, et al. Comparative evaluation of fecal fat excretion induced by orlistat and chitosan. Obes Res 2001;9:364-7.
A prospective, randomized, open-label, crossover study comparing fecal fat excretion induced by either orlistat (Xenical®) or chitosan (Fat trapper™). Patients received thrice daily supplementation of 120 mg orlistat or 890 mg chitosan for 7 days. A total of 12 healthy patients were enrolled. Feces was collected for days 4-7 and analyzed for fat content. Baseline excretion of fat was 1.36 ± 0.45 g/d. Supplementation with chitosan did not significantly increase fat excretion (0.27 ± 1.02 g/d) as compared to baseline. Orlistat significantly increased excretion as compared to baseline (16.13 ± 7.27 g/d). The claim that chitosan binds fat and helps to eliminate it from the body was not substantiated in this trial.