As many as 75 percent of Americans may not be getting enough vitamin D for optimal health, according to a new report in the Archives of Internal Medicine. Doctors have known for years that vitamin D is good for bones, but now researchers are finding that vitamin D—often called the sunshine vitamin because your body produces it when exposed to the sun—may help ward off a whole host of illnesses, including cancer and heart disease. A team of Harvard scientists recently discovered that among 18,000 men they've been tracking since 1993, those with the highest blood levels of vitamin D were the least likely to have heart attacks, while those with the lowest levels had the highest risk. Other studies have found that increasing vitamin D intake reduces the risk of colorectal cancer, hip fractures, and tooth loss and significantly increases muscle strength.
Ironically, just as researchers are discovering the added importance of vitamin D, Americans are getting less and less of it. Average blood levels of the vitamin declined between 1994 and 2004, report University of Colorado researchers, in part because we've been told to cover up to avoid skin cancer. Those over age 50 may be particularly susceptible to vitamin D deficiency because our skin's ability to produce the vitamin declines as we age, as does our kidneys' ability to convert vitamin D into its active form.
Now some doctors are recommending 10 to 15 minutes of sun exposure a few times a week. Those who don't go out much should consider a 1,000-IU (international units) vitamin D supplement daily.
The Sun Outshines Food as Your Best Source of Vitamin D
To get the vitamin D value of ten minutes' exposure to sunlight, you'd have to eat...
6 1/2 pounds of shiitake mushrooms, or
150 egg yolks, or
3 3/4 pounds of fresh farmed salmon, or
30 servings of fortified cereal, or
2 1/6 pounds of sardines, or
30 cups of fortified orange juice
SOURCE: Michael F. Holick, Ph.D., M.D., the Vitamin D, Skin, and Bone Research Laboratory, Boston University Medical Center, Boston
http://www.aarpmagazine.org/health/sunshine_vitamin.html