Chromium picolinate shows carcinogenic potential in vitro

Chromium picolinate has been shown to mutate Chinese hamster ovary cells, leading Diane Stearns, Ph.D., and her colleagues at Northern Arizona University to conclude that the supplement may have carcinogenic properties in humans. Based on the results from previous research with hamster ovary cells that demonstrated chromium picolinate caused chromosomal aberrations, Stearns sought to explore the role of Cr(III) in Cr(VI)-induced cancers.

Cr(III) and Cr(VI) are the two naturally occurring forms of chromium in nature. Cr(III) is found in plants, and subsequently used in supplements, while Cr(VI) tends to be found in industrial settings--making paints or pigments, leather tanning and steel production. When inhaled, Cr(VI) has been shown to cause lung cancer. "Turns out, once Cr(VI) gets into the body, it turns into Cr(III),"​ Stearns said. "It looks like Cr(III) is involved, at least in part, at causing Cr(VI)-induced cancers."​

The current study, which will be published in the Jan. 15 issue of Mutation Research (www.mutationresearch.com​), involved adding doses of chromium picolinate to hamster ovary cells and recording any mutations that occurred. The highest dose tested was 80 mcg/cm2, or .44 mg/mL. This amount, in terms of the mass applied to the surface area of the dish, was dosed as a particulate and is equal to 1 mM chromium if it were all soluble, according to Stearns.

These doses caused mutations in the hamster ovary cells within a 48-hour period. However, because placing cells in a laboratory setting causes mutations in itself, researchers looked for large amounts of mutation."We saw about 58 times more mutations with our doses of chromium picolinate than we did with untreated cells,"​ Stearns said. "This is 58 mutations per million cells. You don't need that many mutations to get cancer. You need one at the right time and the right place."​

Stearns responded to industry concerns that "the thing that consumers are concerned with and what the industry likes to point out is that the doses we used are higher than doses people would get in a pill. And that's absolutely true. But for this type of test, that's not the point of the test. We are looking at the potential, at a chemical level, if it is possible that [chromium picolinate] is a mutagen, and the answer is yes."​

Stearns continued, explaining that demonstrating a compound is mutagenic is not the same thing as showing it can cause cancer--that can only be demonstrated through animal or human studies. "People have developed these experiments to say that we know that things which mutate DNA tend to cause cancer in humans,"​ she said.