- How It Works
- Purported Uses
- Research Evidence
- Patient Warnings
- Do Not Take If
- Side Effects
- Special Point
- Dosage (Inside MSKCC Only)
Scientific Name
Deacetylated chitin bipolymer
Common Name
Chitosan, kitosan, chitin
Brand Name
Fat Trapper™, Fat Trapper Plus™, Fat Absorb™, Fat Blocker™
Clinical Summary
Chitosan is a derivative of chitin extracted from the exoskeleton of crustaceans, including shrimp, lobster, and clams. It is used as an excipient in pharmaceutical formulations and as a dietary supplement for weight loss, hyperlipidemia, and wound healing. It is also made into an edible film to protect food from spoilage (1). Although marketers of weight loss supplements claim that chitosan can bind with fat in the gut, several clinical trials found no increase in fecal excretion of fat or weight loss as compared to placebo (2) (3) (4). Chitosan may lower low-density lipoprotein (LDL) cholesterol, although an optimal dose and long-term efficacy are not yet established (5) (6). One small clinical study in obese patients found that chitosan supplementation decreased weight, body mass index (BMI), waist circumference, and triglycerides (TG) (7). A systematic review of the published literature also concluded that chitosan reduces total cholesterol, but larger, randomized controlled trials are necessary to determine its effect on other lipoproteins (8). Chitosan may increase total plasma antioxidant activity and lowered indices of oxidative stress in humans (9). Limited clinical data are available regarding efficacy for anemia or chronic renal failure, although chitosan did show benefit in a small randomized study (10). Reported adverse events include constipation and gastrointestinal distress (2). Patients allergic to shellfish should not use this supplement.
Purported Uses
- High cholesterol
- Weight loss
- Wound healing
Constituents
- Polymers: Cationic polysaccharides, similar to cellulose, consisting of glucosamine and N-acetylated glucosamine linked by glycosidic bonds
(11)
Mechanism of Action
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 (5). Increased elimination of fat has not been demonstrated (3). 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 (12). In an in vitro study, chitosan demonstrated an antioxidant effect by reducing albumin carobonyls and hydroperoxides in a time dependent manner (9).
Pharmacokinetics
Not absorbed systemically.
Warnings
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.
Contraindications
Patients with shellfish allergy should not use chitosan.
Herb-Drug Interactions
Vitamins A, D, E, and K: Chitosan may bind fat-soluble vitamins and decrease absorption.
(11)
Herb Lab Interactions
Total cholesterol, LDL
Literature Summary and Critique
Hernández-González SO, et al. Chitosan improves insulin sensitivity as determined by the euglycemic-hyperinsulinemic clamp technique in obese subjects. Nutr Res. 2010 Jun;30(6):392-5.
The objective of this randomized, double-blind study was to evaluate the effect of chitosan on insulin sensitivity through use of the euglycemic-hyperinsulinemic clamp technique. Twelve obese, nondiabetic patients received chitosan tid before meals for 3 months and the control subjects (n=6) received placebo. Serum glucose, total cholesterol, HDL cholesterol, and triglycerides (TGs) were measured at baseline and at the end of the 3 month study. Chitosan signficantly increased insulin sensitivity (2.4 + 1.4 vs 3.6 + 1.4 mg/kg/min, P=.043). There was also a significant decrease in weight (90.7 + 14.2 vs 84.7 + 13.7 kg;P=.027), BMI (34.3 + 2.7 vs 31.6 + 2.2 kg/m2;P=.028), waist circumference (106 + 12 vs 99 + 9 cm;P=0.28) and TGs (2.4 + 0.9 vs 1.6 + 0.9 mmol/L;P=.028) in the group receiving chitosan. No adverse events were observed. The authors concluded that chitosan increased insulin sensitivity and decreased weight, BMI, waist circumference, and TG in obese patients.
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.
References
- Cagri A, Ustunol Z, Ryser ET. Antimicrobial edible films and coatings. J Food Prot. 2004 Apr;67(4):833-48.
- Pittler MH, et al. Randomized, double-blind trial of chitosan for body weight reduction. Eur J Clin Nutr 1999;53:379-81.
- Guerciolini R, et al. Comparative evaluation of fecal fat excretion induced by orlistat and chitosan. Obes Res 2001;9:364-7.
- Pittler MH, Ernst E. Dietary supplements for body-weight reduction: a systematic review. Am J Clin Nutr. 2004 Apr;79(4):529-36.
- Maezaki Y, et al. Hypocholesterolemic effect of chitosan in adult males. Biosci Biotech Biochem 1993;57:1439-44.
- Tai TS, et al. Effect of chitosan on plasma lipoprotein concentrations in type-two diabetic subjects with hypercholesterolemia. Diabetes Care 2000;23:1703-4.
- Hernández-González SO, González-Ortiz M, Martínez-Abundis E, et al. Chitosan improves insulin sensitivity as determined by the euglycemic-hyperinsulinemic clamp technique in obese subjects. Nutr Res. 2010 Jun;30(6):392-5.
- 8. Baker WL, Tercius A, Anglade M, et al. A meta-analysis evaluating the impact of chitosan on serum lipids in hypercholesterolemic patients. Ann Nutr Metab. 2009; 55(4):368-74.
- Anraku M, Fujii T, Furutani N, et al. Antioxidant effects of a dietary supplement: reduction of indices of oxidative stress in normal subjects by water-soluble chitosan. Food Chem Toxicol. 2009 Jan;47(1):104-9.
- Jing SB, et al. Effect of chitosan on renal function in patients with chronic renal failure. J Pharm Pharmacol 1997;49:721-3.
- Koide SS. Chitin - chitosan: properties, benefits, and risks. Nutrition Research 1998;18:1091-101.
- Stone CA, et al. Healing at skin graft donor sites dressed with chitosan. Br J Plast Surg 2000;53:601-6.
How It Works
Bottom Line: Insufficient clinical evidence exists to support the efficacy of chitosan for weight loss or cholesterol reduction. Further study is needed to confirm these effects. 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 shells of sea creatures. Chitin is not absorbed in 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.
Purported Uses
- For weight loss
Insufficient clinical evidence exists to support the use of chitosan alone (without dietary changes or exercise) for weight loss. - To lower their cholesterol
Some clinical trials support this use, but its long-term effectiveness is unknown. - To treat anemia associated with chronic kidney failure
One clinical trial supports this use, but more research is needed. - Topically, for improved wound healing
Laboratory evidence and one clinical trial support this use.
Research Evidence
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.
Patient Warnings
- 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.
Do Not Take If
- You are pregnant (chitosan decreases intestinal absorption of vitamins A, D, E, K, and calcium, which are important during pregnancy).
- You are allergic to shellfish (chitosan is composed of shellfish exoskeletons).
Side Effects
- Constipation
- Flatulence
- Gastrointestinal distress symptoms (bloating, cramping)
Special Point
Chitosan’s ability to increase fat excretion is questionable. Any attempt at weight loss or cholesterol reduction should include dietary modifications and/or exercise.
Dosage (Inside MSKCC Only)
This field is only visible to only Inside MSKCC users.
Aliases
Fat Trapper™
Kitosan
E-mail your questions and comments to aboutherbs@mskcc.org.
