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Chitosan for weight loss

Clinical bottom line: Based on trials that have not been independently replicated, chitosan supplement of four tablets per day together with a calorie-controlled diet is associated with an additional 3.28 kg weight loss over 28 days (95% confidence interval (1.5 to 5.1) when compared with diet alone. This benefit is statistically significant and of clinical relevance. There are also significantly larger reductions in blood lipid levels and decreases in blood pressure. Overall, rates of adverse effects were low, and patients receiving chitosan experienced less adverse effects than patients receiving diet alone. Further independent research is required to replicate these finding.

Chitosan is an over-the-counter food supplement used for weight loss. It is a cationic polysaccharide derived from the cuticle of crustacea, and has properties similar to cellulose.

Systematic review

Ernst E, Pittler MH. Chitosan as a treatment for body weight reduction? A meta-analysis. Perfusion, 1998; 11:461-465.

Date review completed: January 1988

Number of trials included: 5

Number of patients: 386

Control group: placebo or calorie-controlled diet

Main outcomes: weight loss, blood pressure, blood lipid levels

Inclusion criteria were randomised, double-blind, placebo-controlled trials of chitosan for weight loss; chitosan main active ingredient in preparation; published or unpublished reports in any language.

Reviewers summarised trial findings and pooled weight loss data using RevMan 3.01 to calculate the weighted mean difference with 95% confidence interval (random effects model).


Five trials were carried out in 386 overweight patients (approximately 10-25% overweight). In all trials patients were treated with 4 tablets/day of chitosan for 28 days, but trials did not report on tablet contents. Where patients were treated with calorie controlled diet, this was in the range of 1000-1100 kcal/day. Reviewers note that all trials were provided by one manufacturer, and were not available on standard electronic bibliographic databases.

Four trials compared chitosan plus diet with placebo plus diet. Four of four trials showed significantly more weight loss with chitosan than with diet alone, with a weighted mean difference of 3.28 kg (95% CI 1.5 to 5.1). Of these, two of two trials showed significantly larger decreases in blood pressure with chitosan, and three of three trials showed significantly larger decreases in blood lipids with chitosan. Two of two trials reported ease of bowel movements with chitosan.

The fifth trial did not test for differences between treatments (chitosan plus diet, chitosan alone or diet alone). However, weight loss appeared better with chitosan plus diet.

Adverse effects

Five trials reported on adverse effects, and four of these stated that there were adverse effects. These ranged from 2 to 5% for chitosan plus diet and from 5 to 18% for diet alone. Reviewers did not describe these in further detail.

Further reading

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