Anything that's marketed as a health or dietary supplement (basically, anything that falls under https://en.wikipedia.org/wiki/Dietary_Supplement_Health_and_... ) is unregulated by the FDA--no efficacy studies, not even safety studies are required for marketing.

They are required to list active ingredients, but unlike drug manufacturers, there is no regular inspection to make sure that they're actually producing the things they say they're making. And judging from the several reports I've seen, the manufacturers are so lazy that they can't be bothered to actually acquire the active ingredient.

Whatever you think about Big Pharma, they are saints compared to the supplement industry.