Let the sun shine, and soak up that vitamin D

There's something simple you can do to help protect yourself against ailments ranging from cancer to depression. Chances are, you're not taking the cure.

It's vitamin D, and some experts believe as many as 50 percent of healthy adults and children are deficient in this essential nutrient.

Doctors across the country have begun prescribing high doses to patients who are surprised to learn they are deficient. Yet doctors and researchers say the vitamin D problem could be solved if we just got out in the sun.

Q: What's so important about vitamin D?

A: For years, doctors have known that vitamin D helps build strong bones by promoting the absorption of calcium. Vitamin D was added to milk more than 50 years ago to combat the common childhood bone disease of rickets. But recent research indicates D is important to almost all body tissues. Low levels of vitamin D have been linked to increased risk of breast and prostate cancer, colon polyps, multiple sclerosis, Type 1 diabetes, muscle weakness -- even depression and schizophrenia.

Q: Why are so many people deficient?

A: Two reasons. People aren't spending enough time in the sun, and it's hard to get enough vitamin D from food. The best way to get it is by being in the sun, since skin produces plenty of D when exposed to the sun's rays.

But office workers and kids playing video games often don't spend enough time outdoors to make the D they need. And when they are outside, they are probably wearing sunscreen. Sunscreen with an SPF of 8 blocks more than 95 percent of the sun's capacity to make vitamin D in your skin.

A cup of fortified milk, yogurt or orange juice contains about 100 International Units of vitamin D. Canned salmon contains 300 to 600 IU.

Doctors used to think 400 IU daily was enough for most adults. But new research indicates that is too low. Dr. Michael McClung, director of the Oregon Osteoporosis Center, recommends that adults get 1,000 to 2,000 IU of vitamin D each day -- unless their blood calcium is too high or they have had kidney stones.

Q: Who is most at risk of vitamin D deficiency?

A: "The farther you live from the equator and the less opportunity you have for regular sun exposure, the more likely you are to be deficient," says Charlotte internist Charles Rich.

Older adults are more at risk. Obesity and liver or kidney disease also increase your risk. Blacks and people with darker skin are more at risk, because their skin is less able to synthesize vitamin D from the sun.

Q: What are the symptoms of deficiency?

A: Often there are none. Debra Wilform, 49, of Charlotte learned she was low in vitamin D after a blood test during a routine physical last year. She had no symptoms. Her doctor prescribed 50,000 IU of D2 once a week for six weeks, then once a month for six months. She is to be retested this month.

Q: How much vitamin D do I need, and what are the best sources?

A: There's still disagreement on how much D is enough. The New England Journal of Medicine says adults and children need 800 to 1,000 IU of vitamin D daily if they're not getting enough sun exposure. McClung says it is safe for adults to take 1,000 to 2,000 IU daily. You would need to drink 10 glasses of milk to get 1,000 IU.

Cautious sun exposure is the easiest way to get enough vitamin D. The National Institutes of Health says 10 to 15 minutes in the sun at least twice a week with your arms, hands, face or back exposed without sunscreen is usually enough.

Children and healthy adults make about 25,000 IU of D by spending 15 minutes in the sun with their face and arms exposed before applying sunscreen, says McClung. Because D is stored in fat and muscle, you can build up reserves to draw on later. But the farther north you live, the harder it is to get enough D from sun exposure alone. From November through February, people living north of Atlanta make little or no vitamin D by being outdoors.

Q: Should I be tested?

A: Ask your doctor. The test costs about $100 and is often covered by insurance. For many people, McClung just recommends over-the-counter supplements.