An evidence-based review that studied previous trials of the weight loss supplement chitosan - also marketed as chitopearl and chitin - has found that while it may be an effective aid to weight loss, many of the trials into its effectiveness were limited by poor methodology. The researchers said that it showed some promise in treating obesity but has not been shown conclusively to be an effective weight loss aid. Chitosan is sold through alternative medicine outlets and is derived from chitin - which is found the in the shells of lobsters and other shellfish.
The review, appearing in the The Cochrane Library, looked into the results of 14 previous trials that included more than 1,000 overweight or obese adults with an average age of 44. Eleven of the studies included both men and women, while three included women only. The study subjects were given either chitosan (in doses ranging from less than a quarter of a gram to 15 grams a day) or a placebo for periods ranging from one month to six months.
On the positive side, those who received chitosan had an average weight loss of almost 4 pounds more than those who received a placebo. Additionally, their cholesterol and blood pressure levels also decreased more than those in the placebo group and no side effects were observed in the group taking chitosan.
But the lead researcher of the study, Cliona Ni Mhurchu, of the University of Auckland, was less optimistic, saying "chitosan may be an effective aid to weight loss but many of the included trials have been limited by poor methodology and reporting."
Ni Mhurchu added that "There is cheap and easy access to over-the-counter treatments and many people have the perception that herbal or natural remedies are safer than prescription medication. The manufacturers of supplements and herbal products should be obliged to provide evidence of efficacy before putting them on the market. People mistakenly believe that the manufacturers do have to prove the efficacy of the product and therefore think they are effective. The perception that such products are safer than prescription medication is wrong; there is a risk without adequate safety and monitoring regulations."