Copper, an obesity-tackling gold?

If you want to flush that stubborn fat away forever, then add copper-rich food to your diet as a team of scientists believes it boosts fat burning in the body.

Though small amounts of copper are essential to health - oysters, liver, beans and nuts are good sources - copper's role in metabolism has been unclear: Some studies found that it boosted fat burning, others that it depressed it.

University of California, Berkeley, Lawrence Berkeley National Laboratory and Howard Hughes Medical Institute researchers have now clarified the critical role that copper plays in nutrition: It helps move fat out of fat cells - called adipocytes - and into the blood stream for use as energy.

Without enough copper, fat builds up in fat cells without being utilized, said Christopher Chang, the Class of 1942 Chair and a professor of chemistry and of molecular and cell biology at UC Berkeley.

"Unlike other studies that link copper levels both to increased or decreased fat metabolism, our study shows definitively how it works - it's a signal that turns on fat cells," said Chang, adding "If we could find a way to burn fat more efficiently, this could be a big contribution to dealing with obesity and diabetes."

The team succeeded in tracking down exactly how copper works: It releases a brake on fat burning. Normally, a second messenger molecule called cyclic-AMP (cAMP) activates the enzymes that break down the fat molecules. They found, however, that another enzyme (phosphodiesterase 3, or PDE3) blocks cAMP, probably to prevent fat breakdown when it is not needed, such as when we're couch potatoes. Copper blocks this enzyme, thereby "putting a brake on a brake," Chang said.

Chang cautions against ingesting copper supplements as a result of these studies, however. Too much copper can lead to imbalances in other essential minerals, including zinc.

The study appears online in the journal Nature Chemical Biology.