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Mineral Spirits

Selenium in your dietmay be
a source of smiles.

Selenium has shown mpressive cancer-prevention prowess in rats and other critters.

But the formerly obscure mineral may also be crucial for proper brain function. Although researchers haven't yet figured out its exact role, it appears selenium helps us maintain a happy, healthy mood.

A clue comes from a study in which 12 men, holed up in a research facility for four months, were fed either a high- or low-selenium diet. Those on the reduced-selenium regimen--and whose initial selenium levels were low--were more prone to depression and hostility, report biochemist Wayne Chris Hawkes, Ph.D., and clinical psychologist Linda Hornbostel, Ph.D., in Biological Psychiatry (Vol. 39, No. 1).

Though the findings fit together nicely with a British study in which selenium supplements boosted subjects' mood, it's unlikely that selenium deficiency is responsible for much depression in the U.S., says Hawkes, a researcher at the USDA Agricultural Research Service. How much of the mineral you get depends less on what you eat than where that food comes from. If your fruits, veggies, and livestock are raised in selenium-poor soil, you may be at risk for deficiency. But selenium levels are adequate in most U.S. farmland.

Not so, however, in New Zealand and parts of China, according to Hawkes. (In the USDA study, in fact, the low-selenium group was fed New Zealand beef.) In such countries, dietary selenium levels could be insufficient for optimal mood maintenance.

Selenium's importance is underscored by the fact that when the body's stock is being depleted, the brain is the last organ to give up its supply But scientists still have little idea what the brain is doing with its stash, or why low levels would alter mood.