Chitosan Overview

Chitosan is a form of fiber chemically processed from crustacean shells. Like other forms of fiber, such as oat bran, chitosan is not well digested by the human body. As it passes through the digestive tract, it seems to have an ability to bond with ingested fat and carry it out in the stool. For this reason, it has been tried as an agent for lowering cholesterol and reducing weight. However, the results in studies have been more negative than positive.

In addition, chitosan has been tried as a treatment for kidney failure and as an aid in wound healing.

Note:We do not recommend the use of chitosan in children or pregnant women due to concerns about possible growth retardation (see Safety Issues below).

Chitosan can be extracted from the shells of shrimp, crab, or lobster. It is also found in yeast and some fungi. Another inexpensive source of chitin is "squid pens," a byproduct of squid processing; these are small, plastic-like, inedible pieces of squid that are removed prior to eating.

The standard dosage of chitosan is 3 to 6 g per day, to be taken with food.

Chitosan can deplete the body of certain minerals (see Safety Issues below). For this reason, when using chitosan, it may be helpful to take supplemental calcium , vitamin D , selenium , magnesium , and other minerals.

Also, according to a preliminary study in rats, taking vitamin C along with chitosan might provide additional benefit in lowering cholesterol. ¹

High Cholesterol

An 8-week, double-blind, placebo-controlled trial of 51 women found that use of chitosan at a dose of 1,200 mg twice daily slightly reduced LDL ("bad") cholesterol as compared to placebo, but did not affect total or HDL ("good") cholesterol levels. ² Another 8-week trial, this one enrolling 84 people, also found modest benefits. ³ However, a 4-month, double-blind, placebo-controlled trial of 88 individuals found no improvement in cholesterol with 1,000 mg 3 times daily of a different chitosan product. ⁴ A 7-month study of 84 men given placebo or 1,200 mg of chitosan daily also failed to find benefit. ⁵ Furthermore, in a 10-month, double-blind, placebo-controlled study of 130 men and women, use of a special microcrystalline form of chitosan at a dose of 1,200 mg twice daily again failed to improve cholesterol profile. ⁶ These contradictory results suggest that if chitosan actually improves cholesterol profile at all, it does so to only a minimal extent.

Weight Loss

Chitosan has been widely advocated as a weight loss supplement, on the basis of its supposed ability to bind fat in the digestive tract. However, despite some positive results ⁷ the largest and best designed trial failed to find benefit. ⁸ In this 6-month, double-blind, placebo-controlled study of 250 overweight people, use of chitosan at a dose of 3 g daily failed to enhance weight loss to any meaningful extent as compared to placebo.

Other studies have also failed to find significant benefit. ⁹

Kidney Failure

People with kidney failure experience numerous health problems, including anemia, fatigue, and loss of appetite. In one open study , researchers tested chitosan supplements in 80 people with kidney failure receiving ongoing hemodialysis treatment. Half the participants were given 45 mg tablets for a total of about 1,500 mg of chitosan daily for 12 weeks; the other half were not given a supplement. ¹⁰ Those in the treatment group showed a significant decrease in urea and creatinine levels. Further, they had a rise in hemoglobin levels and reported improved overall strength, appetite, and sleep. However, these results must be taken with grain of salt, for only double-blind, placebo-controlled studies can prove a treatment effective. (For information on why this is so, see Why Does This Database Rely on Double-blind Studies? )

1. Kanauchi O, Deuchi K, Imasato Y, et al. Increasing effect of a chitosan and ascorbic acid mixture on fecal dietary fat excretion. Biosci Biotechnol Biochem. 1994;58:1617-1620.
2. Wuolijoki E, Hirvelä T, Ylitalo P. Decrease in serum LDL cholesterol with microcrystalline chitosan. Methods Find Exp Clin Pharmacol. 21(5):357-61.
3. Bokura H, Kobayashi S. Chitosan decreases total cholesterol in women: a randomized, double-blind, placebo-controlled trial. Eur J Clin Nutr. 57(5):721-5.
4. Ho SC, Tai ES, Eng PH, Tan CE, Fok AC. In the absence of dietary surveillance, chitosan does not reduce plasma lipids or obesity in hypercholesterolaemic obese Asian subjects. Singapore Med J. 42(1):6-10.
5. Mhurchu CN, Dunshea-Mooij C, Bennett D, Rodgers A. Effect of chitosan on weight loss in overweight and obese individuals: a systematic review of randomized controlled trials. Obes Rev. 6(1):35-42.
6. Metso S, Ylitalo R, Nikkilä M, Wuolijoki E, Ylitalo P, Lehtimäki T. The effect of long-term microcrystalline chitosan therapy on plasma lipids and glucose concentrations in subjects with increased plasma total cholesterol: a randomised placebo-controlled double-blind crossover trial in healthy men and women. Eur J Clin Pharmacol. 59(10):741-6.
7. Schiller RN, Barrager E, Schauss AG, et al. A randomized, double-blind, placebo-controlled study examining the effects of a rapidly soluble chitosan dietary supplement on weight loss and body composition in overweight and mildly obese individuals. J Am Nutraceutical Assoc. 2001;4:42-49.
8. Mhurchu CN, Poppitt SD, McGill AT, Leahy FE, Bennett DA, Lin RB, Ormrod D, Ward L, Strik C, Rodgers A. 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. 28(9):1149-56.
9. Pittler MH, Abbot NC, Harkness EF, Ernst E. Randomized, double-blind trial of chitosan for body weight reduction. Eur J Clin Nutr. 53(5):379-81.
10. Jing SB, Li L, Ji D, Takiguchi Y, Yamaguchi T. Effect of chitosan on renal function in patients with chronic renal failure. J Pharm Pharmacol. 49(7):721-3.