Only a blood test can reveal for certain if a person is deficient in vitamin D

People's Pharmacy

Health & Fitness

September 05, 2004|By Joe Graedon and Teresa Graedon | Joe Graedon and Teresa Graedon,King Features Syndicate

How would I know whether I am low in vitamin D? I always use sunscreen, and I heard that it interferes with vitamin D formation. I am lactose intolerant, so I don't drink milk, which I know is a good source of vitamin D.

If I take a supplement, how much is safe? I read that too much can be toxic.

It is hard to tell if you are deficient without a sophisticated blood test (25-hydroxy-vitamin D). Millions of Americans are low in this crucial nutrient, which is formed in the skin when it is exposed to sunshine. Sunscreen can block vitamin D manufacture.

Not only is vitamin D essential for calcium absorption and strong bones, it also is crucial for healthy muscles, heart and nerves. It contributes to blood pressure control, and there is tantalizing evidence that it may reduce the risk of breast, prostate, colon and other cancers.

Dr. Michael Holick, an authority on vitamin D, recommends getting vitamin D from sun exposure when possible. The usual recommendation of 400 IU (International Units) in oral form supplies about 40 percent of an adult's daily requirement. To avoid toxicity, limit daily intake to 2,000 IU.

In their column, Joe and Teresa Graedon answer letters from readers. Write to them in care of King Features Syndicate, 888 Seventh Ave., New York, NY 10019, or e-mail them via their Web site,

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