Popular Diet Supplement May Be A Cancer Risk

This research has been peer-reviewed and will soon appear in the American Chemical Society journal Chemical Research in Toxicology.

Chromium picolinate is claimed to reduce body fat and build muscle. It also has been suggested that the supplement reduces the risk of cardiovascular disease and the symptoms of diabetes. It often is an ingredient in products ranging from sports drinks and gum to pills.

The health claims for chromium are based on its status as an essential human nutrient required for normal carbohydrate and fat metabolism. The Alabama scientists believe it does this job by making the insulin receptor work better. Still, chromium's role in these processes is not well understood. The element is needed only in trace amounts, but the U.S. Department of Agriculture (USDA) says that more than 90% of American diets contain less than the minimum recommended daily allowance of chromium and dietary sources are extremely poorly absorbed by the body.

Chromium picolinate, on the other hand, is more readily taken in during digestive processes. Furthermore, University of Alabama chemists John B. Vincent, Ph.D., and Stephen A. Woski, Ph.D., say their laboratory has found the compound is remarkably stable and unaffected by water, buffers, or blood serum proteins. "If it's stable enough that it gets into the cells intact," says Vincent, "then it could be a big concern."

The Alabama studies advance the work of the late Dartmouth University chemist Karen Wetterhahn, Ph.D., who died from a widely publicized mercury-poisoning accident. In a 1995 paper she demonstrated that chromium picolinate can get into cells, at least in a lab dish. Her work further showed that, once inside those laboratory cells, it appeared to induce cleavage of chromosomal DNA. Until now, though, there was no solid explanation for just how chromium picolinate caused the damage.

"Simple chromium compounds don't do this," says Vincent. "They have to have ligands -- something that binds to chromium -- that make the properties just right and picolinate is one of those ligands."

Vincent found that chromium picolinate reacts with common biochemicals, like vitamin C. He says the products "can then catalyze a reaction with oxygen to generate the potent DNA-damaging hydroxyl radical." Indeed, when Vincent added "physiologically relevant concentrations" of chromium picolinate to laboratory solutions of DNA, much of the DNA was broken, he said.

It is not known what actually happens in humans, or even animals when chromium picolinate is consumed. A recent USDA study fed rats a diet rich in the compound for 24 weeks and did not see any ill effects. But Vincent asks, "what happens in six months, or a year, or longer?"

"I would definitely be concerned about taking this nutritional supplement based on what we've found," concludes Vincent. "Careful investigation into the effects of long-term diet supplementation with chromium picolinate are needed to evaluate its mutagenic and carcinogenic potentials. In addition, development of other readily absorbable sources of chromium that lack the DNA-damaging ability of chromium picolinate seems warranted."

A nonprofit organization with a membership of nearly 159,000 chemists and chemical engineers, the American Chemical Society publishes scientific journals and databases, convenes major research conferences, and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.