Studies finding link to heart attack, diabetes and multiple sclerosis risks

SEATTLE — Dreary northern winters are infamous for inducing depression. But being starved for sunlight can do more than kick you into a psychic hole.

A growing body of evidence suggests it can raise your risk of cancer, increase susceptibility to heart attack, diabetes and other disorders, and at least partly account for the region’s sky-high rates of multiple sclerosis.

The reason is vitamin D, an essential nutrient produced in abundance by skin exposed to the sun’s rays. Long dismissed as being important mainly for strong bones, the so-called sunshine vitamin is now recognized as a key player throughout the body, including the immune system.

Experts say vitamin D deficiency is much more common than previously believed — especially in northern climes, where solar radiation from October to March is too puny to maintain healthy levels.

“You’re in a dark, gloomy place,’’ said Bruce Hollis, a leading vitamin D researcher at the Medical University of South Carolina. “In the winter, you could stand outside naked for five hours and nothing is going to happen.’’

Increased use of sunscreen has turned a seasonal shortfall into a year-round condition for many people. A recent survey in Britain found 87 percent of adults tested during winter, and more than 60 percent in summer, had subpar vitamin D levels. Doctors in many parts of the world — including California — report a resurgence of childhood rickets, soft bones caused by lack of vitamin D.

While supplements offer a cheap and easy solution, Hollis and other researchers argue the recommended intake is too low to provide many health benefits. A Canadian medical organization advises that pregnant and nursing women take 10 times the amount suggested in the U.S.

“You’re more likely to live longer and you’re less likely to die of serious chronic disease if you have adequate vitamin D on board,’’ said Dr. Michael Holick of Boston University School of Medicine, one of the world’s top experts. “It may well be the most important nutrient of the decade.’’

When Lisa Hill, 54, went to her doctor complaining of joint pain, she was surprised to get a diagnosis of vitamin D deficiency. “I had never heard of it,’’ she said.

Since leaving her native Southern California, her sun exposure has dropped dramatically.

“You’re like a little mole in a hole,’’ she said. “You just don’t get much sun here.’’

Many doctors once scoffed at the notion of vitamin D deficiency, but testing has become more routine and is covered by most insurance.

University of Washington heart surgeon Dr. Donald Miller Jr. tested 78 of his patients and found three-quarters had “insufficient’’ levels of vitamin D.