What Is It?
Health Benefits

Dosage Information

Guidelines for Use

General Interaction

Possible Side Effects

Evidence Based Rating Scale

What Is It?

The shells of crabs, lobsters, and other crustaceans contain a non-digestible fiber called chitosan.  When extracted and taken in supplement form with meals, chitosan reportedly encourages weight loss by binding to Fat molecules in the digestive tract, preventing the body from absorbing the fat.

Health Benefits

Chitosan is most commonly marketed as a weight-loss aid, but the fiber is also being studied for its effects on cholesterol levels and as an anti-inflammatory agent that may be beneficial in treating the chronic intestinal Inflammation of Crohn's disease.  A natural fiber, chitosan is often touted as a treatment for constipation.  Additional claims include benefit in promoting the healing of lesions and ulcers, acting as an antacid, inhibiting plaque and tooth decay and offering anti-tumor action.  However, scientific research is limited.

Specifically, chitosan may help to:

Promote weight loss.  Some small studies have found that taking chitosan may aid in weight loss.  Whether chitosan is safe and effective as a diet aid remains controversial, however.  In a trial conducted in Helsinki in 1994, people who used chitosan for a month in conjunction with a Calorie-controlled diet lost, on average, 8% of their body weight.  (1) This translates into 16 pounds for a 200-pound person.  How much of this weight loss was due to the chitosan and how much to the calorie restriction is unknown.

Other studies, however, have not reported such positive findings.  A carefully designed 1999 trial in England involving 34 overweight individuals, found that when participants were instructed to maintain a normal diet, rather than restricting caloric intake, chitosan supplements were no better than a Placebo in reducing body weight.  (2) A similar study of 88 obese individuals in 2001 also found chitosan was no better than placebo in reducing body weight, body composition, blood pressure, or lipid profile.  (3) A 24-week study of 250 overweight and obese adults taking three grams of chitosan or placebo daily found no significant differences between the groups in body weight, body mass index, waist circumference, body fat percentage, blood pressure, serum lipids, plasma glucose, fat-soluble vitamins, fecal fat, or health-related quality of life. (4)

Some advertisements encourage taking chitosan so that you can "indulge" in a fatty meal.  This is definitely not the case.  Several studies have shown that taking chitosan does not significantly increase fecal fat excretion.  While chitosan may bind some of the fats in the digestive tract, it certainly does not cover them all.  The bottom line is that anyone wishing to try chitosan for weight loss will still have to watch total calorie intake, reduce fat in the diet, and exercise.  (4-7)

A 2005 Cochrane Database meta-analysis of studies found that while many studies showed that chitosan supplementation might modestly reduce weight compared to placebo, when only higher quality, larger studies are analyzed, the effect of chitosan on weight loss is minimal (approximately 0.5 kg - about one pound - when taken for one to six months) and unlikely to be of clinical significance.  (8)

Lower cholesterol.  Researchers are examining whether chitosan may lower cholesterol (another effect of its fat-binding qualities).  A 1999 study of 34 overweight individuals in England showed that taking one to three grams of chitosan daily for one month did not significantly decrease total cholesterol or low-density lipoprotein (LDL) in patients with high cholesterol.  (2) A 2001 study of 88 obese individuals also showed no positive benefit of chitosan on lipid profiles.  (3) And a 2003 randomized, placebo-controlled, double-blind crossover study of 130 healthy men and women with moderately increased total cholesterol levels found that taking three grams of chitosan daily had no effect on the plasma lipids or glucose levels.  (9)

However, a small study of 21 overweight men and women with normal cholesterol levels found that taking 1.2 grams of chitosan in combination with 1.2 grams of glucomannan daily for one month reduced total cholesterol by 7%, LDL cholesterol by 10% and increased high-density lipoprotein (HDL) by 4% in these individuals.  (10) It’s unclear whether glucomannan alone would have had this effect or whether it is the combination that is necessary.  In a 2003 study of 90 women with mild to moderate hypercholesterolemia, taking 1.2 grams of chitosan daily for eight weeks led to a 7% reduction in LDL cholesterol.  (11) The 2005 Cochrane Database meta-analysis of studies found that taking 1 to 4.5 grams of chitosan daily for longer than four weeks may reduce total cholesterol by about 6 mg/dL in patients with or without hyperlipidemia.  (8)

Kidney/Renal Disease.  For patients on long-term stable dialysis, a supplement of 45mg of chitosan three times a day contributed to decreased cholesterol, urea and creatinine levels, increased Hemoglobin levels, and improvements in appetite, sleep, and sense of well-being after four weeks in 40 patients compared to controls. (23)

Treat Crohn's disease.  The anti-inflammatory and fat-excreting properties of chitosan may be useful in reducing the discomfort associated with Crohn's disease, a chronic inflammatory condition of the intestines. A 2003 pilot study of 11 patients with Crohn's disease found that taking one Gram of chitosan in combination with Vitamin C daily for eight weeks helped to increase fat excretion and to decrease intestinal inflammation.  (12) More research is needed.

Speed wound healing.  Chitosan has shown wound healing activity, speeding the healing process in patients with skin grafts, duodenal ulcers and skin ulcers.  When used topically in wound dressings, chitosan has been shown to speed the healing of skin grafts and burns because it acts as a barrier yet allows for drainage and healthy air circulation.  (13-16) Chitosan also has been shown to speed the healing of foot and leg ulcers.  In a 2008 study of 85 patients with diabetic foot ulcers, pressure ulcers or leg ulcers, using a chitosan wound dressing for 21 days significantly increased the healing rate when compared to inactive gauze.  In the treatment group, 29 of 34 wounds (85%) healed completely and none became infected; the remaining five wounds healed during the follow-up period.  By contrast, in the control group, four pressure ulcers healed, but the remaining wounds deteriorated and became infected, requiring antibiotics.  (18) In a 2011 study of 16 patients with 26 venous leg ulcers, treatment with a triple compression bandage plus a chitosan gel led to a significantly higher reduction of the ulcer area than treatment with a compression bandage alone.  (19) More research is needed.

Duodenal ulcers.  Just as skin ulcers are improved with chitosan therapy, duodenal ulcers seem to benefit as well.  In a 2003 study, bacterial specimens from the stomachs of 122 patients with duodenal ulcers were treated with chitosan.  H. pylori was suppressed, and 85% of the other bacteria of the mucosa were sensitive to it.  With chitosan treatment, ulcer scarring was accelerated, which promoted the healing process. (17)

Prevent tooth decay and treat periodontal disease.  Preliminary evidence indicates that a chewing gum supplemented with chitosan can decrease the number of oral bacteria that lead to tooth decay better than non-supplemented gum.  In a 2007 double-blind study of 50 healthy subjects who chewed a gum containing chitosan at five minute intervals for a total of 80 minutes per day, the treatment resulted in significantly decreased number of cavity-causing bacteria compared to a control group.  (20) In a 2010 study of patients, using chitosan-containing polyherbal toothpaste led to a 70% reduction in plaque and an 85% reduction in bacterial count.  (21) Whether reduction of these bacteria actually results in reduction of decay has yet to be demonstrated.  With periodontal disease, the supporting structures of the teeth including gums, ligaments, and bone, become inflamed and damaged exposing the base of the teeth and allowing them to loosen.  One early study demonstrated that a mixture of chitosan with vitamin C in the form of a gel could be used to fill some of the defects of periodontal disease and reduce tooth mobility. (22)


  • capsule
  • gel
  • gum
  • tablet

Dosage Information

For Crohn's disease: Taking 1 gram of chitosan in combination with vitamin C daily has been used.

For dental health: Chewing a gum supplemented with chitosan for five-minute intervals for up to 80 minutes a day has been used.

For high cholesterol: Taking 1 to 3 grams of chitosan daily has been used. A combination of 1.2 grams of chitosan and 1.2 grams of glucomannan daily has also been used.

For renal failure with dialysis: 1.35 grams has been used three times daily.

For weight management: Taking 1 to 5 grams of chitosan daily has been used. A specific combination of 2.5 grams of chitosan in combination with 1 gram of psyllium, 200 mg of malic acid, and 100 mg of aloe daily (Fat Magnet, Natural Balance Inc.) has also been used.

For topical wound care: No specific dosage has been established for the topical application of chitosan. Applying a chitosan gel to bandage dressing has been used. 

Guidelines for Use

Chitosan is considered safe when taken within proper dosage guidelines.

To prevent the absorption of fats, chitosan should be taken with or before meals.

General Interaction

Although chitosan appears to be quite safe, in theory, it could block the absorption of fat-soluble vitamins (vitamins A, D, E and K) as well as essential fatty acids (the "good" fats, like omega-3 and omega-6).  In one case report, the blood test results for anti-coagulant activity (INR) was increased in a patient taking the anticoagulant warfarin, presumably due to decreased vitamin K absorption. Be cautious with this combination.  Check with your doctor before using chitosan and/or other supplements.

Possible Side Effects

Chitosan is generally well-tolerated, but rare side effects can include stomach upset, nausea, flatulence, increased stool bulk and constipation.


Don't take chitosan if you have an allergy to shellfish.

Chitosan doesn't get absorbed into the bloodstream, which means it's largely free of the side effects that so many people experience with numerous prescription (and nonprescription) weight-loss medications and supplements. 

Because no extensive safety studies have been done, women who are pregnant or breast-feeding and children under age 14 should avoid chitosan


1. Abelin J, Lassus A. Fat binder as weight reducer in patients with moderate obesity. ARS Medicine, Helsinki, Aug-Oct;1994.
2. Pitter MH, et al. Randomized, double-blind trial of chitosan for body weight reduction. Eur J Clin Nutr. May 1999;53(5):379-81.
3. Ho SC, Tai ES, Eng PH, et al. In the absence of dietary surveillance, chitosan does not reduce plasma lipids or obesity in hypercholesterolaemic obese Asian subjects. Singapore Med J. 2001 Jan;42(1):6-10.
4. Mhurchu CN, Poppitt SD, McGill AT, et al. The effect of the dietary supplement, Chitosan, on body weight: a randomized controlled trial in 250 overweight and obese adults. Int J Obes Relat Metab Disord. 2004;28:1149-56.
5. Guerciolini R, Radu-Radulescu L, Boldrin M, et al. Comparative evaluation of fecal fat excretion induced by orlistat and chitosan. Obes Res. 2001 Jun;9(6):364-7.
6. Gades MD, Stern JS. Chitosan supplementation does not affect fat absorption in healthy males fed a high-fat diet, a pilot study. Int J Obes. 2002;26:119-22.
7. Gades MD, Stern JS. Chitosan supplementation and fat absorption in men and women. J Am Diet Assoc. 2005;105:72-7.
8. Ni Mhurchu C, Dunshea-Mooij C, Bennett D, Rodgers A. Chitosan for overweight or obesity. Cochrane Database Syst Rev. 2005;(3):CD003892.
9. Metso S, Ylitalo R, Nikkilä M, Wuolijoki E, et al. The effect of long-term microcrystalline chitosan therapy on plasma lipids and glucose concentrations in subjects with increased plasma total cholesterol: a randomized placebo-controlled double-blind crossover trial in healthy men and women. Eur J Clin Pharmacol. 2003 Dec;59(10):741-6.
10. Gallaher DD, Gallaher CM, Mahrt GJ, et al. A glucomannan and chitosan fiber supplement decreases plasma cholesterol and increases cholesterol excretion in overweight normocholesterolemic humans. J Am Coll Nutr. 2002 Oct;21(5):428-33.
11. Bokura H, Kobayashi S. Chitosan decreases total cholesterol in women: a randomized, double-blind, placebo-controlled trial. Eur J Clin Nutr. 2003;57:721-5.
12. Tsujikawa T, Kanauchi O, Andoh A, et al. Supplement of a Chitosan and ascorbic acid mixture for Crohn's disease. A pilot study. Nutrition. 2003;19:137-9.
13. Peh K, Khan T, Ch'ng H. Mechanical, bioadhesive strength and biological evaluations of chitosan films for wound dressing. J Pharm Pharm Sci. Sep 2000;3(3):303-11.
14. Stone CA, Wright H, Clarke T, et al. Healing at skin graft donor sites dressed with chitosan. Br J Plast Surg. Oct 2000;53(7):601-6.
15. Mi FL, Shyu SS, Wu YB, et al. Fabrication and characterization of a sponge-like asymmetric chitosan membrane as a wound dressing. Biomaterials. Jan 2001;22(2):165-73.
16. Azad AK, Sermsintham N, Chandrkrachang S, Stevens WF. Chitosan membrane as a wound-healing dressing: characterization and clinical application. J Biomed Mater Res. May 2004;69B(2):216-22.
17. Bondarenko VM, Chervinets VM, Vorob'ev AA. Role of persisting opportunistic bacteria in the pathogenesis of the gastric and duodenum ulcer. Zh Mikrobiol Epidemiol Immunobiol. Jul 2003;(4):11-7.
18. Kordestani S, Shahrezaee M, Tahmasebi MN, et al. A randomised controlled trial on the effectiveness of an advanced wound dressing used in Iran. J Wound Care. 2008 Jul;17(7):323-7.
19. Sandoval M, Albornoz C, Muñoz S, et al. Addition of chitosan may improve the treatment efficacy of triple bandage and compression in the treatment of venous leg ulcers. J Drugs Dermatol. 2011 Jan;10(1):75-9.
20. Hayashi Y, Ohara N, Ganno T, et al. Chewing chitosan-containing gum effectively inhibits the growth of cariogenic bacteria. Arch Oral Biol. 2007;52:290-4.
21. Mohire NC, Yadav AV. Chitosan-based polyherbal toothpaste: as novel oral hygiene product. Indian J Dent Res. 2010 Jul-Sep;21(3):380-4.
22. Muzzarelli R, Biagini G, Pugnaloni A, et al. Reconstruction of parodontal tissue with chitosan. Biomaterials 1989;10:598-603.
23. Jing SB, Li L, Ji D, et al. Effect of chitosan on renal function in patients with chronic renal failure. J Pharm Pharmacol 1997;49:721-3.

Evidence Based Rating Scale

The Evidence Based Rating Scale is a tool that helps consumers translate the findings of medical research studies and what our clinical advisors have found to be efficacious in their personal practice into a visual and easy to interpret format. This tool is meant to simplify the information on supplements and therapies that demonstrate promise in the treatment of certain conditions.








Several studies indicate efficacy in speeding the healing of wounds such as burns. (13-19)

Crohn's disease
Preliminary evidence indicates potential efficacy when taken in combination with vitamin C. More research is needed. (12)
Gum disease  
One small study using a gel of chitosan and vitamin C demonstrates effective reduction of tooth mobility resulting from periodontal disease. (22)

High cholesterol  
Several studies and a Cochrane Database review indicate efficacy in reducing total cholesterol. However, conflicting evidence exists. More research is needed. (2-3, 8-11)
Kidney/Renal disease
In one study there was improvement in blood tests and quality of life among stable dialysis patients given chitosan. (23)
Tooth decay  <
Date Published: 04/18/2005
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