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Q. I've been hearing a lot recently about the dangers of vitamin D deficiency. What's the story?

A: In a nutshell, vitamin D deficiency is a huge problem. We don't get nearly enough of this vitally important nutrient.

Many nutritionists think that vitamin D is one of the most underrated vitamins in the world. Our recommended daily allowances have been around 400 mg a day, but many doctors and nutritionists now believe it should be increased to 1,000 mg. In one hospital study, 76 percent of mothers coming into the hospital were severely vitamin D deficient, and 81 percent of their infants were as well. The American Academy of Pediatrics last spring instructed pediatricians to prescribe that all children, especially breast-fed babies, take vitamin D supplements through adolescence. And The Center for Disease Control reported that 42 percent of African American women during their child bearing years were vitamin D deficient, especially by the end of winter. By some estimates, 40-60 percent of elderly people are deficient.

Vitamin D is responsible for telling your body to absorb calcium from your diet more efficiently, to make sure that your blood calcium is normal and to ensure that you have healthy bones. In fact, without enough activated vitamin D, you can take all the calcium supplements in the world, and it won't do you all that much good.

Besides being absolutely necessary for strong bones, vitamin D also helps control cell growth, which is why scientists now believe that vitamin D may protect against breast cancer, colon cancer and prostate cancer. They've known for a while that people who live in the higher latitudes are more prone to vitamin D deficiency and are also more prone to developing common cancers and dying of them, especially prostate, colon and breast cancer. Your skin is literally a pharmaceutical factory for this incredible vitamin, but to work, it has to be turned on by sunlight.

Low levels of vitamin D have been suggested as a factor in depression, as well as a number of autoimmune diseases.

Your body makes vitamin D, but it makes it in the skin when you're exposed to sunlight. Our collective sun phobia isn't helping matters. While no one suggests reckless noon-day sunbathing without protection, we may have gone overboard in our avoidance of sunshine. For most Caucasians living where there is sunlight, if you expose about 10 percent of your body a couple times a week, that's enough to get your vitamin D requirement. Darker people or people who live in the northern latitudes need more. The point is, don't be sun-phobic. The sun offers life; it offers the ability to make a life-enhancing vitamin that most people are deficient in, and it offers the ability to regulate feel-good chemicals in the brain so that your sense of well being is improved.

And if you still want to stay out of the sun, for goodness sake, take a supplement. I recommend at least 1,000 IUs a day. Many people will do better with more. According to Al Sears' excellent book "The Sun Book," a young adult with fair skin will make 20,000 units of vitamin D in just a few minutes of sun exposure.

Maybe our bodies know what we need better than we do!

More articles from Jonny Bowden

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• Alli: Magic Pill? Well, No
• Bone Balance

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