Chitosan .. a fat blocker??

Ads for chitosan claim it can lower cholesterol and produce rapid weight loss by blocking the absorption of fat. Is this true?

Chitosan is derived from chitin, a polysaccharide found in the exoskeleton of shellfish such as shrimp, lobster, and or crabs. Many sellers claim that chitosan causes weight loss by binding fats in the stomach and preventing them from being digested and absorbed. Some refer to it as a "fat magnet." It is even marketed as a weight-control product for dogs.

Although chitosan can decrease fat absorption, the amount contained in the capsules is too small to have much of an effect on cholesterol levels. Moreover, with better, more predictable cholesterol-lowering products available, it doesn't make much sense to use chitosan for that purpose. There is no evidence that chitosan is effective for weight control.