Does chromium cause cancer? What the research does and doesn't show

The one long-term government carcinogenicity study of chromium picolinate — two years, in rats and mice, at doses far above a supplement serving — found no cancer signal in five of six test groups, and an equivocal finding in the sixth. Most of the public concern about chromium and cancer actually traces back to a different, industrial form of the mineral, not the one in dietary supplements.

What the evidence doesn't support

It doesn't support chromium picolinate, the supplement form, as something that clearly causes cancer at the doses people actually take. The definitive test of that question — a 2-year U.S. National Toxicology Program feeding study — used doses many thousands of times a typical human serving and still found no cancer signal in female rats or in mice of either sex. It also doesn't support treating "chromium" as one substance: most of the documented cancer risk associated with chromium is specific to hexavalent chromium, an industrial and environmental form encountered through inhalation, not the trivalent form used in food and supplements.

What the studies found

The U.S. National Toxicology Program ran a 2-year feeding study of chromium picolinate monohydrate in F344/N rats and B6C3F1 mice, at doses up to 50,000 parts per million in the diet — equivalent to roughly 90 to 2,630 mg/kg of body weight per day depending on sex and species, thousands of times higher than a typical human supplement serving. No neoplasms or other lesions were attributed to chromium picolinate in female rats or in mice of either sex. In male rats only, at the highest dose tested, the incidence of a specific benign tumor (preputial gland adenoma) was increased above the range seen in historical control animals. The study's official conclusion was "equivocal evidence of carcinogenic activity" in male rats specifically, and no evidence of carcinogenic activity in female rats or in mice. Standard genetic-toxicology screens (bacterial mutation tests, blood-cell tests in mice) were mostly negative, with one equivocal result in female mice at the highest dose tested.

A separate 2007 laboratory study tested chromium picolinate for DNA-damaging (genotoxic) effects in mice and in human cells. In live mice given up to 3 mg/kg, and in most cell-culture conditions, chromium picolinate showed no genotoxic effect. The one exception was a small but statistically significant increase in DNA damage in human white blood cells — and only when those cells were exposed to chromium picolinate with no serum present in the culture, a non-physiological condition that doesn't reflect how the compound behaves in a living body. The authors' own conclusion was that any DNA-damaging effect requires high concentrations under artificial laboratory conditions.

Separately, hexavalent chromium — written Cr(VI), a different, more reactive form used in industrial processes like chrome plating, welding and pigment manufacturing — is a well-documented cause of lung cancer through inhalation exposure in occupational settings. That's the chromium behind most "chromium causes cancer" concern, and it's a different substance, taken in through a different route, from the trivalent chromium picolinate or chromium chelates sold as dietary supplements. See what is chromium for how the forms differ, and chromium side effects for more on the "chromium 6" distinction.

Questions people ask

Does chromium cause cancer?

The one long-term carcinogenicity study of chromium picolinate, run over 2 years at doses thousands of times a typical serving, found no cancer signal in female rats or mice of either sex, and an equivocal finding limited to one benign tumor type in male rats at the highest dose. That's not the same as "no risk at any dose," but it's the most direct evidence available, and it doesn't show a clear cancer-causing effect at doses anywhere close to what a supplement provides.

Does chromium picolinate cause cancer?

See above — chromium picolinate monohydrate is the specific compound tested in the National Toxicology Program's 2-year study, at doses far exceeding supplement levels, with the result described above.

Is chromium 6 the same as the chromium in supplements?

No. Chromium 6 (hexavalent chromium) is an industrial and environmental form linked to lung cancer through inhalation exposure. Dietary supplements use trivalent chromium — chromium picolinate or a chromium chelate — a different, less reactive form taken by mouth, not inhaled.

Can chromium oxide give cancer?

Chromium oxide (chromium III oxide, sometimes used as a green pigment) is a different compound from the chromium picolinate and chromium chelates most commonly sold as dietary supplements, and it isn't the form tested in the carcinogenicity study above — no data on chromium oxide specifically was found in this literature, so this page can't answer that question.

When to talk to a doctor

Cancer screening and any personal or family cancer history are conversations for a doctor, not a supplement search. Chromium is not a treatment for cancer, and nothing above should be read as a statement that any supplement is risk-free at every dose — it's a summary of what the one long-term carcinogenicity study, and the genotoxicity data alongside it, actually found. If you have questions about a specific product or dose, ask a doctor or pharmacist.

Related reading: what is chromium, chromium side effects, and how to choose a chromium supplement.