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For years, the media have trumpeted the vital role calcium plays in preventing osteoporosis -- a bone-thinning disease that afflicts 10 million Americans. Almost 34 million more are estimated to have low bone mass, placing them at increased risk for osteoporosis. The calcium clamor is so loud it sometimes drowns out messages about another nutritional necessity, vitamin D. Without enough vitamin D, the body cannot absorb calcium and deposit it in the bones.

The human body makes its own vitamin D when ultraviolet-B (UV-B) radiation from the sun interacts with a chemical in the skin. About five to 15 minutes of unfiltered sun exposure a day is usually enough. But the sunshine method isn't 100 percent reliable for everyone, particularly for older individuals, who are at the highest risk for weakened bones and fractures. Reasons for this include:

·         The skin's ability to make vitamin D from UV-B becomes less efficient as we age.

·         Darker skin blocks out up to 95 percent of UV-B rays.

·         Sunscreens absorb UV-B before the skin can form vitamin D.

·         The earth's ozone layer screens out UV-B in northern latitudes during the winter.

·         It is not always possible to get outdoors on sunny days.

As a result, many senior citizens are vitamin-D deficient or near-deficient, especially during winter.

According to leading vitamin D researcher Michael Holick M.D., of Boston University Medical Center, at least 40 percent of hip-fracture patients in the northeast United States and Europe are vitamin-D deficient. One of Holick's studies showed some senior citizens inMaine lose 3 percent to 4 percent of bone mass in their hips and spines in the fall and winter and regain some of it in the spring and summer.

More recently, Holick tested 290 Boston hospital patients, ranging in age from 18 to 95 and found that 57 percent did not have enough vitamin D circulating in their blood. In such cases, the blood raids the skeleton for the calcium it needs, thus raising the risk of osteoporosis.

These and other findings indicate dietary sources of vitamin D become increasingly important as we age. The recommended daily dietary allowance for vitamin D in adults is 400 IU (international units). According to the National Institute on Aging, the Dietary Reference Intake Guidelines recommend 600 IU for people older than 70.

Sources of vitamin D

Vitamin D is available from three sources:

·         Fortified milk and products made from fortified milk (not yogurt), as well as some fish.

·         Supplements, including multivitamins with vitamin D and calcium supplements with vitamin D.

·         Sun-exposed skin.

By law, a quart of milk must contain 400 IU of vitamin D, but studies show 80 percent of milk samples nationwide have more or less than that amount and 14 percent had no detectable vitamin D at all. Fortified breakfast cereals, egg yolks and fatty fish (including tuna, sardines and mackerel) are rich sources of vitamin D. Some breakfast and nutrition bars and drinks provide 100 IU to 140 IU of vitamin D per serving. Vitamin D is also available in multivitamins and calcium supplements.

If you take supplements, read labels to avoid overdosing on vitamin D. According to the Mayo Clinic Health Letter, ingesting more than 2,000 IU of vitamin D a day for a prolonged period poses the risk of toxic side effects. Symptoms of vitamin D poisoning may include nausea, headache, excessive urination, hypertension, kidney stones, kidney damage and other problems.

 

For  More   Information:  Please  consult  your   physician  on  your  next  visit.