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Vitamins, Minerals and Dietary Supplements

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Chitosan

What is chitosan? Why do we need it?

Chitosan is a fiber-like substance derived from chitin, a polysaccharide found in the exoskeletons of crabs, shrimp and other shellfish. It possesses a positive ionic charge, which gives it the ability to chemically bond with negatively charged fats, lipids and bile.

Unlike dietary fiber, chitosan cannot be digested. However, it appears to have a variety of gastrointestinal benefits. Repeated animal studies (and some preliminary human studies) have shown that chitosan supplements can lower LDL (or "bad") cholesterol while raising HDL (or "good") cholesterol. Other studies suggest that large amounts of chitosan taken in conjunction with vitamin C may reduce dietary fat absorption.

How much chitosan should I take?

No suggestible levels have been determined for chitosan at present. However, most human research has used between 3-6 grams of chitosan per day with meals.

What are some good sources of chitosan? What forms are available?

Chitosan is found in the shells and exoskeletons of crustaceans such as shrimp and crab. It is available as a tablet, capsule or powder.

What can happen if I don't get enough chitosan? What can happen if I take too much? Are there any side-effects I should be aware of?

Because chitosan is not classified as an essential nutrient, deficiency and toxicity levels have yet to be established.

Because chitosan absorbs dietary fat, it may also impair the absorption of fat-soluble vitamins, such as vitamins A, D, E and K. People who are allergic to shellfish, or who have problems absorbing certain vitamins and minerals, should not use chitosan. It should also not be used by children or pregnant women.

At present, there is no evidence of any adverse drug reactions with chitosan.

References

  • Deuchi K, Kanauchi O, Imasato Y, et al. Decreasing effect of chitosan on the apparent fat digestibility by rats fed on a high-fat diet. Biosci Biotech Biochem 1994;58:1613—6.
  • 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.
  • Koide SS. Chitin-chitosan: properties, benefits and risks. Nutr Res 1998;18:1091—101
  • Maezaki Y, Tsuji K, Nakagawa Y, et al. Hypocholesterolemic effect of chitosan in adult males. Biosci Biotech Biochem 1993;57:1439—44.
  • Terada A, Hara H, Sato D, et al. Effect of dietary chitosan on faecal microbiota and faecal metabolites of humans. Microb Ecol Health Dis 1995;8:15—21.

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