Brief Answer:
Information

Detailed Answer:
Hello and welcome,

The jury is still out on determining Chitosan's effectiveness in lowering cholesterol. Some (small) studies have shown significant decreases in cholesterol levels, other studies have not shown any significant change. The trials are still small, mostly pilot (initial) research.

Here is an article summarizing a variety of research papers, but again, the number of people in the trials was small: http://www.medscape.com/viewarticle/458896_4

So - since much of the research on it is small and the results are conflicting, it is still in the category of "insufficient evidence" regarding it's effectiveness.

I'm sorry I can't give you an answer such as a percentage of effectiveness, as we just don't know yet. More research has to be done.

I hope this information helps.

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