The regulatory system we have in the US for selling herbal supplements is screwed up. I've thought so for many years, and we're not the only country that fits that description, either. The system is screwed up in so many important ways that it's hard to know where to start, but how about back at the very basics - quality control?
Try this paper from BMC Medicine out (open access) and see what you think. The authors, from the DNA barcoding initiative at Guelph, tested 44 different brands of various herbal supplements, purchased in both the US and Canada. They found ridiculous levels of contamination. In fact, contamination is not the right word: one-third of the samples had no detectable amounts of the herb on the label. Instead, there were invasive weeds, ornamental plants from China, ground rice, soybeans, what have you. 10 of the 12 companies whose products were tested had at least one in this lovely category; 4 of them had nothing but.
This brings up several interesting questions: for one, how come this garbage continues to sell? Could it be that many of these preparations are of no benefit other than the placebo effect, which means that lawnmower scrapings will indeed work just as well? Second, who's ripping off whom? I would assume that some of these companies are buying from middlemen and repackaging, in which case, they're getting hosed (and passing the hosing along to you!) Doesn't anyone have even a passing interest in seeing if they've been sold the right material, or do they just not care, since it sells anyway?
When drug companies sell products of poor quality, the roof should come down on them, and I'm glad when it does. But these sleazeballs - is there even a roof to bring down? Now, I realize that some people will look at my background, and say, sure, this is someone who works in the pharma industry, of course he's going to put down these safe, natural, effective herbal medicines. Why, those would put his kind out of business if people just realized how wonderful they were! But I'm not denying that some herbal preparations can be used as medicines. If they can, though, they should have to prove it (the way we do in the drug industry), and they should have to actually sell what it says on the label, the way we do. Selling people a bunch of ditch clippings from a Chengdu compost pile is not acceptable, and if you're a big proponent of herbal remedies, you should be even more upset about this crap than I am.
More: Here's the New York Times on this story.