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A Little Sun Might Shield Against Skin Cancer

Posted: January 30, 2007

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Kathleen Egan, a professor of epidemiology at the H. Lee Moffitt Cancer Center and Research Institute in Tampa, Fla., agreed that the study findings are "tantalizing" but need further study.

Especially since the release of Berwick's melanoma study, "there's been an awful lot of questions about how -- or if -- vitamin D has a part to play in potentially offering some [cancer] protection under some circumstances," she said. "But it's very difficult to tease out, because the main human source of vitamin D is, in fact, sunlight exposure, which is also the most important risk factor for melanoma."

Nutritionists have known for decades that sunlight stimulates vitamin D production in the skin. In fact, this natural process is the body's major source of the nutrient. A proper amount of vitamin D is crucial to bone health, "and there's also a bunch of evidence that vitamin D may have a role in preventing colon cancer, although there's still some controversy about that," Weinstock said.

So, how much sunlight is enough to get the ideal amount of vitamin D?

Katharine Tallmadge, a Washington, D.C., dietitian and a spokeswoman for the American Dietetic Association, suggests that most people can probably get the U.S. Department of Agriculture's recommended 400 daily IUs of vitamin D by spending a half-hour to an hour outside per day.