I have never associated turmeric (curcumin) with feeling bad, other than the fact it can play havoc with indegestion if I try to take it on an empty stomach.
I love the stuff and take it regularly as a cancer preventive. I take Super Bio-Curcumin from Life Extension Foundation, which I get at a discounted price at iherb.com. It is much, much more absorbable than regular curcumin, which the body normally absorbs very poorly. If you take regular turmeric/curcumin you can help the absorption somewhat by taking it along with coconut milk or regular black pepper.
I personally take 400 to 800 mg regularly. For people who have agressive, difficult and/or late stage cancers we recommend up to 2500 to 3000 mg per day.
The herb itself works great and is dirt cheap. An extract is available but is really not any more beneficial. You can get just as much if not more curcumin from eating a yellow curry dish. And curcumin is poorly absorbed anyway, so larger doses are not any more beneficial.
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