Chitosan is a polysaccharide found in the shells of crustaceans.
Where is it found?
Chitosan is extracted from the shells of crustaceans, such as shrimp and crab.
Why do dieters use it?*
Some dieters say that chitosan
helps decrease appetite.
What do the advocates say?*
Chitosan has been shown to inhibit fat absorption in animals, although in studies in humans
chitosan did not inhibit fat absorption. Some research has found that taking chitosan during a
weight loss program increases the amount of weight loss. In other studies, however, chitosan
was ineffective.
It is important to note that supplementing with chitosan will also cause the body to
excrete the important fat-soluble vitamins A, D, E, and K, too.
How much is usually taken by dieters?
A double-blind Polish study found that people taking 1,500 mg of chitosan three times daily
during a weight loss program lost significantly more weight than people taking a placebo with
the same program.1 Other studies using smaller amounts of chitosan have reported no
effects on weight loss.234
Are there any side effects or interactions?
While no long-term studies of the effects of chitosan on human health have been done,
animal studies suggest that this compound could inhibit the absorption of minerals and fat-soluble vitamins. Adverse effects on the growth of children
and on the outcome of pregnancy are also
possible.5 In addition, although chitosan-included alterations in intestinal flora
are believed to be beneficial, the possibility that these changes may have negative long-term
consequences has not been ruled out. People with
intestinal malabsorption syndromes should not use chitosan.
At the time of writing, there were no well-known drug interactions
with chitosan.
*Dieters and weight-management advocates may claim benefits for
chitosan based on their personal or professional experience. These are individual opinions and
testimonials that may or may not be supported by controlled clinical studies or published
scientific articles on chitosan. For more complete and detailed information, including
references and safety information, see Chitosan as
a nutritional supplement.
References (To view, roll mouse over the "References" heading; to hide, click on the heading)
1. Zahorska-Markiewicz B, Krotkiewski M, Olszanecka-Glinianowicz M,
Zurakowski A. Effect of chitosan in complex management of obesity. Pol Merkuriusz Lek
2002;13:129–32 [in Polish].
2. 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;42:006–10.
3. Pittler MH, Abbot NC, Harkness EF, Ernst E. Randomized, double-blind
trial of chitosan for body weight reduction. Eur J Clin Nutr
1999;53:379–81.
4. Muzzarelli RA. Clinical and biochemical evaluation of chitosan for
hypercholesterolemia and overweight control. EXS 1999;87:293–304 [review].
5. Koide SS. Chitin-chitosan: properties, benefits and risks. Nutr
Res 1998;18:1091–101 [review].
The information presented in Healthnotes is for informational purposes
only. It is based on scientific studies (human, animal, or in vitro), clinical
experience, or traditional usage as cited in each article. The results reported may not
necessarily occur in all individuals. For many of the conditions discussed, treatment with
prescription or over the counter medication is also available. Consult your doctor,
practitioner, and/or pharmacist for any health problem and before using any supplements or
before making any changes in prescribed medications. Information expires September 2008.
