What suzanneM has said about chromium picolinate is very true. Several studies have been done which show that the supplement cause DNA mutations and actually enters cell walls, and "stays" there. Doing a search on Google will lead you in the right direction.

However, all is not lost. These same studies say that a different Chromium supplement in the form of Chromium Polynicotinate does not the produce the same mutations and is safe for use.

I take 200mcg a day of the "Chromium Polynicotinate" version.

JFF