Low vitamin D may raise death risk

CHICAGO - Adults with a vitamin D deficiency are more likely to die than adults who have high levels, another indication of the nutrient's vital role in guarding against ailments from heart disease to cancer, US researchers said yesterday.

The report follows several recent studies that have shown vitamin D may protect against a host of ailments, including heart disease, cancers of the colon and breast, diabetes, and tuberculosis.

People with the lowest levels of the so-called sunshine vitamin had a 26 percent higher risk of death over eight years compared with those with the highest levels, researchers reported in the Archives of Internal Medicine. Dr. Michal Melamed of Albert Einstein College of Medicine in New York and colleagues studied 13,331 adults for an average of 8.7 years. Of the 1,806 people who died, 777 died of heart disease, though there were too few to conclude a vitamin deficiency caused fatal heart problems. Vitamin D deficiency was also linked to a higher risk of death from cancer, diabetes, and other diseases.

"The fact that all the deaths went up, but we could not find the specific cause, may be because vitamin D plays a role in both cancer and heart disease and potentially other things" such as diabetes, Melamed said by phone.

Scientists have evidence the vitamin helps lower blood pressure, reduce inflammation, and boost the immune system.

Vitamin D deficiency is common: About one-quarter of American adults have less than the 18 nanograms per milliliter of blood that Melamed recommended as minimal. About two in five American men and half of women have less than the 28 nanograms per milliliter considered healthy.

The body makes vitamin D when the skin is exposed to sunlight, and it is also found in fatty fish like salmon. But many people do not get enough of it, especially in winter in higher latitudes when the sun's rays are less direct and people are inside or covered up.

It is so important that it is added to milk and other foods.

Melamed's team noted that heart problems are more likely to arise in winter when vitamin D levels tend to be lower. And cancer survival rates are higher when the disease is diagnosed in summer when vitamin D levels are higher.

But too-high levels of the vitamin were also found to be harmful, Melamed said, though not as harmful as a deficiency.

"I think vitamin D is like everything else in the body: there has to be an ideal level," she said.