What does Chitosan do?
Likedietary fiber, chitosan is not digestible but may have beneficial effectson the gastrointestinal tract. Chitosan may reduce the absorption of bile acidsor cholesterol, either of which may cause a lowering of blood cholesterol.¹ This effect has been repeatedlydemonstrated in animals, and a preliminary human study showed that 3–6 gramsper day of chitosan taken for two weeks resulted in a 6% drop in cholesterol anda 10% increase in HDL (the “good”) cholesterol.² Anoth high in salt.

er preliminary study showed a43% lowering of total cholesterol in people being treated for kidney failurewith dialysis who took 4 grams per day of chitosan for twelve weeks. This groupalso appeared to have improved kidney function and less severe anemia afterchitosan treatment.³

Chitosan in large amounts given with vitamin C has been shown to reducedietary fat absorption in animals fed a high-fat diet.^{4 56} Unfortunately, mineral andfat-soluble vitamin absorption is also reduced by feeding animals large amountsof chitosan.⁷ No studies have been done on theeffects of chitosan on dietary fat absorption in humans.

Animal and preliminary human research suggests that chitosan may prevent theblood pressure-elevating effects of a high-salt meal, possibly by reducing theabsorption of chloride. A small study showed that men taking 5 grams of chitosanwith a meal

ulted in no elevation in blood pressure, while thesame meal without chitosan significantly elevated systolic blood pressure.⁸

Chitosan may also have an effect on bacteria in the intestines. A small humanstudy found that taking 3–6 grams per day of chitosan for two weeks reducedindicators of putrefaction in the intestines,⁹ a change that might help preventdiseases, such as colon cancer.¹⁰

Where is it found?
Chitosan is a supplement commonly extracted from theshells of crustaceans, such as shrimp and crab.

Chitosan has been used in connection with the following conditions(refer to the individual health concern for complete information):

Who is likely to be deficient? Chitosan is not an essential nutrient, sodeficiencies do not occur.

 How much is usually taken? Most human research has used 3–6grams per day with meals.

 Are thereany side effects or interactions? While no long-term studies of the effectsof chitosan on human health have been done, animal studies suggest that harmfuleffects on mineral and fat-soluble vitamin absorption, on maintenance of normalintestinal flora, and on normal growth in children and during pregnancy arepossible.¹¹ People with intestinal malabsorptionsyndromes should not use chitosan. At the time of writing, there were no well-known drug interactions withchitosan.

References:
1. Koide SS. Chitin-chitosan:properties, benefits and risks. Nutr Res 1998;18:1091–101 [review].
2. Maezaki Y, Tsuji K, Nakagawa Y, et al. Hypocholesterolemic effect of chitosanin adult males. Biosci Biotech Biochem 1993;57:1439–44.
3. Jing SB, Li L, Ji D, et al. Effect of chitosan on renal function in patientswith chronic renal failure. J Pharm Pharmacol 1997;49:721–23.
4. Deuchi K, Kanauchi O, Imasato Y, et al. Effect of the viscosity ordeacetylation degree of chitosan on fecal fat excreted from rats fed on ahigh-fat diet. Biosci Biotech Biochem 1995;59:781–85.
5. Deuchi K, Kanauchi O, Imasato Y, et al. Decreasing effect of chitosan on theapparent fat digestibility by rats fed on a high-fat diet. Biosci BiotechBiochem 1994;58:1613–16.
6. Kanauchi O, Deuchi K, Imasato Y, et al. Increasing effect of a chitosan andascorbic acid mixture on fecal dietary fat excretion. Biosci Biotech Biochem1994;58:1617–20.
7. Deuchi K, Kanauchi O, Shizukuishi M, et al. Continuous and massive intake ofchitosan affects mineral and fat-soluble vitamin status in rats fed on ahigh-fat diet. Biosci Biotech Biochem 1995;59:1211–16.
8. Kato H, Taguchi T, Okuda H, et al. Antihypertensive effect of chitosan inrats and humans. J Trad Medicinen 1994;11:198–205.
9. Terada A, Hara H, Sato D, et al. Effect of dietary chitosan on faecalmicrobiota and faecal metabolites of humans. Microb Ecol Health Dis1995;8:15–21.
10. Bone E, Tamm A, Hill M. The production of urinary phenols by gut bacteriaand their possible role in the causation of large bowel cancer. Am J ClinNutr 1976;29:1448–54.
11. Koide SS. Chitin-chitosan: properties, benefits and risks. Nutr Res1998;18:1091–101 [review].