Common Names

  • Kitosan
  • Chitin
  • Polyglucosamine

For Patients & Caregivers

How It Works

Chitosan has been promoted for weight loss and for cholesterol reduction. However, there is not enough evidence to support these uses.

The main ingredient in chitosan (KY-to-san) is chitin, an extract from the shells of sea creatures such as shrimp, lobster, and clams. It can also come from the cell walls of Reishi mushrooms. Marketers promote chitosan as a weight-loss product, claiming it binds to fat and cholesterol to prevent their absorption. However, studies in people have found that chitosan did not increase levels of fat excreted. Other studies suggest it may help improve cholesterol levels. However, more trials are needed before definite conclusions can be drawn.

Chitosan is used as an ingredient in many medical-grade products including hydrogels and bandages to improve wound healing, as well as in dental applications. Scientists think it may enhance the process of new tissue formation.

Purported Uses
  • For weight loss
    There is not enough evidence to support the use of chitosan alone without dietary changes or exercise for weight loss.
  • To lower cholesterol
    Some clinical trials support this use, but long-term effectiveness is unknown.
  • Topically, for improved wound healing
    Laboratory evidence and a clinical trial support this use.
Do Not Take If
  • You are allergic to shellfish or mushrooms: Chitosan comes from either of these sources.
  • You are taking warfarin (Coumadin): A case report indicates that chitosan may increase the blood-thinning effects of this drug.
Side Effects
  • Constipation
  • Flatulence, gas
  • Bloating, abdominal cramping
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For Healthcare Professionals

Scientific Name
Deacetylated chitin bipolymer
Clinical Summary

Chitosan (KY-to-san) is a derivative of chitin, extracted from the exoskeleton of crustaceans, including shrimp, lobster, and clams, and from the cell wall of Reishi mushrooms (13). Chitosan is used as an excipient in pharmaceutical formulations and in biomedical applications including wound dressings. It is also made into an edible film to protect food from spoilage (1). Chitosan is marketed as an all-natural marine fiber to help manage weight and cholesterol.

Animal models suggest antiobesity properties with chitosan (14) (15) (16) (17) and derivative products (18) (19). In one animal study, a combination of capsaicin and chitosan increased this activity (20).

Findings from human studies are conflicting. Although marketers of weight loss supplements claim that chitosan can bind with fat in the intestine, some clinical trials did not find any increase in fecal excretion of fat or weight loss compared with placebo (2) (3) (4) (21). Other studies have had more positive results in combination with additional products or interventions (22) (23). Various studies and meta-analyses suggest chitosan may decrease diastolic blood pressure at higher dosages (32), improve serum lipid profiles (6) (8) (33) (34), and have some benefit on weight management (7) (24) (35) (36). However, more trials are needed before definitive conclusions can be drawn.

Chitosan may increase total plasma antioxidant activity and lower the indices of oxidative stress in humans (9). Limited clinical data are available regarding efficacy for anemia or chronic renal failure (10).

Reported adverse events include constipation and gastrointestinal distress (2). Patients allergic to shellfish or mushrooms should use related supplements with caution.

Purported Uses
  • High cholesterol
  • Weight loss
  • Wound healing
Mechanism of Action

Chitosan is a natural polysaccharide that consists of glucosamine and N-acetylglucosamine copolymers (14). It has been described as biodegradable, nontoxic, non-immunogenic, and biocompatible (25), with properties similar to cellulose (2).

In an in vitro study, chitosan demonstrated antioxidant effects by reducing albumin carobonyls and hydroperoxides in a time-dependent manner (9).

In animal models, antiobesity effects may occur through serum leptin and C-reactive protein modulation (14) or 5’ adenosine monophosphate-activated protein kinase (AMPK) activation and lipogenesis-associated gene inhibition (15). In porcine models, chitosan altered genes influencing appetite and feeding behavior in the small intestine (NPY), adipose tissue (Leptin), and the brain (HCRT, INSR, NMB, GHR, PPARG, NPY5R(17). It also downregulated FABP2 gene expression, increased serum leptin, and significantly altered gut microbial populations (16). In high-fat diet-induced obese rodents, chitosan oligosaccharides improved dyslipidemia and prevented body weight gain by inhibiting adipocyte differentiation (19). As an insoluble fiber, low molecular weight chitosan polyglucosamines can bind to fat in the intestinal lumen, forming a complex that is partially utilized by colon bacteria and partially eliminated (22) (26) (27), but appropriate concentrations are needed. In one of these animal studies, it was suggested that the more likely mechanisms for weight loss could include bacterial energy wasting, as increased acetate and glucose excretion were also present, suggesting that larger amounts of lipids and glucose were available as fuel for bacteria in the colon (26).

Hypocholesterolemic effects from chitosan in murine models were not due to reduced cholesterol absorption efficiency or increases in fecal sterol output, so that a major bile acid-binding capacity was ruled out (28). The more likely scenario is that the fiber’s influence on satiation and satiety reduces food intake suppression and therefore cholesterol (29).

Human studies suggest that it is unlikely that chitosan binds fat in intestines, and could therefore not support this purported mechanism of action (21) (30).

Topical application enhances wound healing by stimulation of granulation tissue. Possible mechanisms include formation of a gel-like fibronectin matrix that facilitates inward epithelial cell migration and the formation of heparin-chitosan complexes that activate growth factors that bind to stabilized heparin (12).


As chitosan products are derived from shellfish or mushrooms, patients who are allergic to these substances should use chitosan with caution.

Adverse Reactions

Constipation, flatulence, and GI distress symptoms (4) (8) (21) (22)

Herb-Drug Interactions

Warfarin (Coumadin): In a case report of an 83-year-old man with hypertensive cardiovascular disease, type 2 diabetes mellitus, and chronic atrial fibrillation who was maintained on warfarin, chitosan appeared to increase the anticoagulant effect of this drug (31).

Dosage (OneMSK Only)
  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. 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.
  13. Mesa Ospina N, Ospina Alvarez SP, Escobar Sierra DM, et al. Isolation of chitosan from Ganoderma lucidum mushroom for biomedical applications. J Mater Sci Mater Med. Mar 2015;26(3):135.
  14. Walsh AM, Sweeney T, Bahar B, et al. Multi-functional roles of chitosan as a potential protective agent against obesity. PLoS One. 2013;8(1):e53828.
  15. Chiu CY, Chan IL, Yang TH, et al. Supplementation of chitosan alleviates high-fat diet-enhanced lipogenesis in rats via adenosine monophosphate (AMP)-activated protein kinase activation and inhibition of lipogenesis-associated genes. J Agric Food Chem. Mar 25 2015;63(11):2979-2988.
  16. Egan AM, Sweeney T, Hayes M, et al. Prawn Shell Chitosan Has Anti-Obesogenic Properties, Influencing Both Nutrient Digestibility and Microbial Populations in a Pig Model. PLoS One. 2015;10(12):e0144127.
  17. Egan AM, O’Doherty JV, Vigors S, et al. Prawn Shell Chitosan Exhibits Anti-Obesogenic Potential through Alterations to Appetite, Affecting Feeding Behaviour and Satiety Signals In Vivo. PLoS One. 2016;11(2):e0149820.
  18. de Souza GI, Santamarina AB, de Santana AA, et al. Preventive effects of chitosan coacervate whey protein on body composition and immunometabolic aspect in obese mice. 2014;2014:281097.
  19. Huang L, Chen J, Cao P, et al. Anti-obese effect of glucosamine and chitosan oligosaccharide in high-fat diet-induced obese rats. Mar Drugs. May 2015;13(5):2732-2756.
  20. Tan S, Gao B, Tao Y, et al. Antiobese effects of capsaicin-chitosan microsphere (CCMS) in obese rats induced by high fat diet. J Agric Food Chem. Feb 26 2014;62(8):1866-1874.
  21. Mhurchu CN, Poppitt SD, McGill AT, et al. The effect of the dietary supplement, Chitosan, on body weight: a randomised controlled trial in 250 overweight and obese adults. Int J Obes Relat Metab Disord. Sep 2004;28(9):1149-1156.
  22. Pokhis K, Bitterlich N, Cornelli U, et al. Efficacy of polyglucosamine for weight loss-confirmed in a randomized double-blind, placebo-controlled clinical investigation. BMC Obes. 2015;2:25.
  23. Jung EY, Jun SC, Chang UJ, et al. L-ascorbic acid addition to chitosan reduces body weight in overweight women. Int J Vitam Nutr Res. 2014;84(1-2):5-11.
  24. Trivedi VR, Satia MC, Deschamps A, et al. Single-blind, placebo controlled randomised clinical study of chitosan for body weight reduction. Nutr J. 2016;15(1):3.
  25. Rios-Hoyo A, Gutierrez-Salmean G. New Dietary Supplements for Obesity: What We Currently Know. Curr Obes Rep. Apr 6 2016.
  26. Bondiolotti G, Cornelli U, Strabbioli RS, et al. Effect of a polyglucosamine on the body weight of male rats: Mechanisms of action. Food Chemistry. 2/1/ 2011;124(3):978-982.
  27. Bondiolotti G, Bareggi SR, Frega NG, et al. Activity of two different polyglucosamines, L112 and FF45, on body weight in male rats. Eur J Pharmacol. Jul 12 2007;567(1-2):155-158.
  28. van Bennekum AM, Nguyen DV, Schulthess G, et al. Mechanisms of cholesterol-lowering effects of dietary insoluble fibres: relationships with intestinal and hepatic cholesterol parameters. Br J Nutr. Sep 2005;94(3):331-337.
  29. Burton-Freeman B. Dietary fiber and energy regulation. J Nutr. Feb 2000;130(2S Suppl):272s-275s.
  30. Gades MD, Stern JS. Chitosan supplementation and fecal fat excretion in men. Obes Res. May 2003;11(5):683-688.
  31. Huang SS, Sung SH, Chiang CE. Chitosan potentiation of warfarin effect. Ann Pharmacother. Nov 2007;41(11):1912-1914.
  32. Huang H, Zou Y, Chi H. Quantitative assessment of the effects of chitosan intervention on blood pressure control. Drug Des Devel Ther. 2018;12:67-75.
  33. Huang H, Zou Y, Chi H, et al. Lipid-Modifying Effects of Chitosan Supplementation in Humans: A Pooled Analysis with Trial Sequential Analysis. Mol Nutr Food Res. Apr 2018;62(8):e1700842.
  34. Lutjohann D, Marinova M, Wolter K, et al. Influence of Chitosan Treatment on Surrogate Serum Markers of Cholesterol Metabolism in Obese Subjects. Nutrients. Jan 11 2018;10(1).
  35. Moraru C, Mincea MM, Frandes M, et al. A Meta-Analysis on Randomised Controlled Clinical Trials Evaluating the Effect of the Dietary Supplement Chitosan on Weight Loss, Lipid Parameters and Blood Pressure. Medicina (Kaunas). Dec 12 2018;54(6).
  36. Huang H, Liao D, Zou Y, et al. The effects of chitosan supplementation on body weight and body composition: a systematic review and meta-analysis of randomized controlled trials. Crit Rev Food Sci Nutr. Apr 16 2019:1-11.
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