Interesting article

"If taken in large doses, it can cause an upset stomach and diarrhea, and, in rare cases, it can cause damage to the liver. "

The problem is, no one knows what defines a large dose, because it is a supplement and has barely been studied long enough. And, as with all supplements, no user can know for sure about its actual efficacy, purity, consistency, or potency. So, "caveat emptor" (buyer, beware).