Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.
For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.
3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.
Refer to label instructions
Chitosan is a fiber-like substance that may reduce fat absorption. One study found it to be an effective weight-loss aid.
Chitosan is a fiber-like substance extracted from the shells of crustaceans such as shrimp and crab. Animal studies suggested that chitosan supplementation reduces fat absorption, but controlled human trials have found no impairment of fat absorption from supplementation with 2,700 mg of chitosan per day for seven days or 5,250 mg per day for four days.1 , 2 A double-blind study found that people taking 1,500 mg of chitosan three times per day during a weight-loss program lost significantly more weight than did people taking a placebo with the same program.3 Similar benefits were seen in another double-blind study that used 3,000 mg of chitosan per day.4 Other studies using smaller amounts of chitosan have reported no effects on weight loss.5 , 6 , 7
Refer to label instructions
Chitosan is a fiber-like supplement that has been shown to lower cholesterol and raise HDL (“good”) cholesterol).
The fiber-like supplement chitosan appears to reduce the absorption of bile acids or cholesterol; either of these effects may cause a lowering of blood cholesterol. 8 This effect has been repeatedly demonstrated in animals, and a preliminary human study showed that 3 to 6 grams per day of chitosan taken for two weeks resulted in a 6% drop in cholesterol and a 10% increase in HDL ("good") cholesterol.9 Another preliminary trial showed a 43% lowering of total cholesterol in people being treated for kidney failure with dialysis who took 4 grams per day of chitosan for 12 weeks. These people also appeared to have improved kidney function and less severe anemia after chitosan treatment. 10 In a double-blind trial, however, administration of 2.4 grams of chitosan per day for three months to people with high cholesterol had no effect on their cholesterol levels. 11 Another study also found no cholesterol-lowering effect of chitosan when taken in amounts up to 6.75 grams per day for 8 weeks.12
Chitosan in large amounts, given with vitamin C, has been shown to reduce dietary fat absorption in animals fed a high-fat diet.13 , 14 , 15 However, the absorption of minerals and fat-soluble vitamins was also reduced by feeding animals large amounts of chitosan.16 In studies in humans, chitosan did not reduce the absorption of dietary fat.17 , 18
Most human research has used 3–6 grams per day with meals.
Chitosan is extracted from the shells of crustaceans, such as shrimp and crab.
Chitosan is not an essential nutrient, so deficiencies do not occur.
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 possible.19 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.
1. 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 Relat Metab Disord 2002;26:119–22.
2. Guerciolini R, Radu-Radulescu L, Boldrin M, et al. Comparative evaluation of fecal fat excretion induced by orlistat and chitosan. Obes Res 2001;9:364–7.
3. 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].
4. Kaats GR, Michalek JE, Preuss HG. Evaluating efficacy of a chitosan product using a double-blinded, placebo-controlled protocol. J Am Coll Nutr 2006;25:389–94.
5. 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.
6. 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.
7. Muzzarelli RA. Clinical and biochemical evaluation of chitosan for hypercholesterolemia and overweight control. EXS 1999;87:293–304 [review].
8. Koide SS. Chitin-chitosan: properties, benefits and risks. Nutr Res 1998;18:1091-101 [review].
9. Maezaki Y, Tsuji K, Nakagawa Y, et al. Hypocholesterolemic effect of chitosan in adult males. Biosci Biotech Biochem 1993;57:1439-44.
10. 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.
11. Metso S, Ylitalo R, Nikkila M, et al. 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 2003;59:741–6.
12. Tapola NS, Lyyra ML, Kolehmainen RM, et al. Safety aspects and cholesterol-lowering efficacy of chitosan tablets. J Am Coll Nutr 2008;27:22–30.
13. Deuchi K, Kanauchi O, Imasato Y, et al. Effect of the viscosity or deacetylation degree of chitosan on fecal fat excreted from rats fed on a high-fat diet. Biosci Biotech Biochem 1995;59:781-5.
14. 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.
15. Kanauchi O, Deuchi K, Imasato Y, et al. Increasing effect of a chitosan and ascorbic acid mixture on fecal dietary fat excretion. Biosci Biotech Biochem 1994;58:1617-20.
16. Deuchi K, Kanauchi O, Shizukuishi M, et al. Continuous and massive intake of chitosan affects mineral and fat-soluble vitamin status in rats fed on a high-fat diet. Biosci Biotech Biochem 1995;59:1211-6.
17. Gades MD, Stern JS. Chitosan supplementation and fecal fat excretion in men. Obes Res 2003;11:683–8.
18. 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 Relat Metab Disord 2002;26:119–22.
19. Koide SS. Chitin-chitosan: properties, benefits and risks. Nutr Res 1998;18:1091–101 [review].
Last Review: 05-01-2013
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The information presented in Aisle7 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 June 2014.
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