A Cochrane review [Abstract] 1 on the effects of the supplement chitosan (deacetylated chitin) as a treatment for overweight and obesity included 15 studies with a total of 1219 subjects. Analyses including all trials indicated that chitosan preparations result in a significantly greater weight loss (weighted mean difference [WMD] -1.7 kg; 95% confidence interval [CI] -2.1 to -1.3 kg), decrease in total cholesterol (-0.2 mmol/l; 95% CI -0.3 to -0.1), decrease in systolic and diastolic blood pressure compared with placebo. There were no clear differences between intervention and control groups in terms of frequency of adverse events or in faecal fat excretion. No trial to date has measured the effect of chitosan on mortality or morbidity. The quality of many studies was sub-optimal. Results obtained from high quality trials indicate that the effect of chitosan on body weight is minimal and unlikely to be of clinical significance.
Comment: The quality of evidence is downgraded by limitations in study quality and by inconsistency (variability in results across studies).
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