Chromium is a mineral believed to enhance insulin action and help restore normal glucose tolerance. One form called chromium picolinate is especially popular because it is one of the more easily absorbed forms.
But in 1995, a report published by researchers at Dartmouth College first sparked controversy about the safety of chromium picolinate. They found that chromium picolinate could damage the genetic material of hamster cells.
Since then, other lab studies done using cell cultures and rats have suggested chromium picolinate causes oxidative stress and DNA damage. Nobody knows yet whether these findings would apply to humans. There have also been some case reports of adverse side effects after taking chromium picolinate supplements. Read the article: Chromium Picolinate Side Effects.