Try getting some good information on chromium picolante, the diet aid, some time. Every company who sells a product based on it gives a lot of "expert testimonial" to further their cause, whereas the FTC point out that the companies involved are being investigated for fraud, and don't point to any research with any sort of backup to their claims of it causing various cancers and the like.

I can't find any official word from the FDA, but I'd really like to (even artificially) boost my metabolism and get my body into some sort of shape without looking like Ally McBeal.