Health Care Professional Information

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, clinical trials did not find any increase in fecal excretion of fat or weight loss 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 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
  • Linear copolymer of β-(1,4)-poly-2-amino-2-deoxy-d-glucose and β-(1,4)-poly-2-acetamido-2-deoxy-d-glucose
    (9)
Mechanism of Action

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

Chitosan is 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.

Adverse Reactions

Reported: Constipation, flatulence, and GI distress symptoms.
(4) (8)

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 significantly 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.

Dosage (Inside MSKCC Only)
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References
  1. Cagri A, Ustunol Z, Ryser ET. Antimicrobial edible films and coatings. J Food Prot. 2004 Apr;67(4):833-48.
  2. Pittler MH, et al. Randomized, double-blind trial of chitosan for body weight reduction. Eur J Clin Nutr 1999;53:379-81.
  3. Guerciolini R, et al. Comparative evaluation of fecal fat excretion induced by orlistat and chitosan. Obes Res 2001;9:364-7.
  4. Pittler MH, Ernst E. Dietary supplements for body-weight reduction: a systematic review. Am J Clin Nutr. 2004 Apr;79(4):529-36.
  5. Maezaki Y, et al. Hypocholesterolemic effect of chitosan in adult males. Biosci Biotech Biochem 1993;57:1439-44.
  6. Tai TS, et al. Effect of chitosan on plasma lipoprotein concentrations in type-two diabetic subjects with hypercholesterolemia. Diabetes Care 2000;23:1703-4.
  7. 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. 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.
  9. 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.
  10. Jing SB, et al. Effect of chitosan on renal function in patients with chronic renal failure. J Pharm Pharmacol 1997;49:721-3.
  11. Koide SS. Chitin - chitosan: properties, benefits, and risks. Nutrition Research 1998;18:1091-101.
  12. Stone CA, et al. Healing at skin graft donor sites dressed with chitosan. Br J Plast Surg 2000;53:601-6.

Consumer Information

How It Works

Bottom Line: Current evidence is insufficient to support the efficacy of chitosan for weight loss or cholesterol reduction.

The main ingredient in chitosan 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

Insulin sensitivity:
Twelve obese, nondiabetic patients received chitosan three times a day before meals for 3 months and the control subjects 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 significantly increased insulin sensitivity. There was also a significant decrease in weight, BMI , waist circumference and TGs in the group on chitosan.  

 

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)
E-mail your questions and comments to aboutherbs@mskcc.org.