Another good thing about Vitamin D

Low levels of vitamin D, the essential nutrient obtained from milk, fortified cereals and exposure to sunlight, doubles the risk of stroke in whites, but not in blacks, according to a new report by researchers at Johns Hopkins.

Stroke is the nation's third leading cause of death, killing more than 140,000 Americans annually and temporarily or permanently disabling over half a million when there is a loss of blood flow to the brain.

Nearly 8,000 initially healthy men and women of both races were involved in the latest analysis, part of a larger, ongoing national health survey, in which the researchers compared the risk of death from stroke between those with the lowest blood levels of vitamin D to those with higher amounts. Among them, 6.6 percent of whites and 32.3 percent of blacks had severely low blood levels of vitamin D, which the experts say is less than 15 nanograms per milliliter. 

Besides helping to keep bones healthy, vitamin D plays an essential role in preventing abnormal cell growth, and in bolstering the body's immune system. The hormone-like nutrient also controls blood levels of calcium and phosphorus, essential chemicals in the body. Shortages of vitamin D have also been tied to increased rates of breast cancer and depression in the elderly. 

How to get more vitamin D?

Michos recommends that people maintain good vitamin D levels by eating diets rich in such fish as salmon and tuna, consuming vitamin-D fortified dairy products, and taking vitamin D supplements. She also promotes brief exposure daily to the sun's vitamin D-producing ultraviolet light. And to those concerned about the cancer risks linked to too much time spent in the sun, she says as little as 10 to 15 minutes of daily exposure is enough during the summer months. 

And about supplements.

If vitamin supplements are used, Michos says that daily doses between 1,000 and 2,000 international units are generally safe and beneficial for most people, but that people with the severe vitamin D deficits may need higher doses under close supervision by their physician to avoid possible risk of toxicity.

The U.S. Institute of Medicine (IOM) previously suggested that an adequate daily intake of vitamin D is between 200 and 600 international units. However, Michos argues that this may be woefully inadequate for most people to raise their vitamin D blood levels to a healthy 30 nanograms per milliliter. The IOM has set up an expert panel to review its vitamin D guidelines, with new recommendations expected by the end of the year. Previous results from the same nationwide survey showed that 41 percent of men and 53 percent of women have unhealthy amounts of vitamin D, with nutrient levels below 28 nanograms per milliliter.