The spotlight in on Vitamin D
YOUR HEALTH
DR. DONOHUE

DEAR DR. DONOHUE: I am a 76-year-old female. Until December 2005, I thought I was in fairly decent health. That's when I suffered a fractured hip. I didn't fall, just sort of slipped down. I have recovered and feel great, and I exercise. Last April, my doctor prescribed 50,000 IU vitamin D once a week. I have been taking it ever since. I get lots of sun. I also take 600 mg of calcium with 200 IU vitamin D twice a day. And I take one multivitamin a day, a Centrum Silver. My doctor wants me to consider taking Fosamax. What's going on? I worry about getting too much vitamin D. How does a person know how much is too much? -- T.W.

ANSWER: Most adults get too little vitamin D. The official recommendation for daily vitamin D intake is 200 IU for those from 19 to 50, 400 IU for those between 51 and 70, and 600 IU for those 71 and older. Many experts believe these recommendations are insufficient and that the daily dose should be 800 IU to 1,000 IU. Vitamin D enhances calcium absorption and plays a critical role, therefore, in keeping bones strong and in preventing fractures. There are hints that vitamin D prevents osteoarthritis, lessens the risk of prostate cancer and helps prevent diabetes and heart disease. Time will tell if all this is true. The stuff about bones is true.

We get vitamin D when sunlight strikes the skin. It turns a substance in the skin known as a "provitamin" into vitamin D. Ten minutes of sunlight on the face and arms, three times a week to daily, is all the sunlight needed for this conversion. Older people's skin is not so efficient in making the vitamin, and those living in northern latitudes can't depend on sunlight conversion in the winter months.

From your weekly 50,000 IU tablet, you get about 7,000 IU of the vitamin daily. Centrum Silver has 500 IU. You get another 400 IU with your daily calcium tablets. So your daily intake is around 8,000 IU. Too much vitamin D can be a problem. It can damage the kidneys and can actually draw calcium from the bones. The upper daily limit is set at 10,000 IU. You haven't crossed the border, but you're in its neighborhood. The 50,000 IU tablet can correct a vitamin D deficiency in six to eight weeks. I'd say you've made that correction. Ask your doctor about stopping this high-dose vitamin therapy. If there is a question about the adequacy of your body store of vitamin D, a blood test can determine if it is too low, too high or just right.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853- 6475. Readers may also order health newsletters from www.rbmamall. com. 2006 North America Syndicate Inc. All Rights Reserved