Too Many Seniors Get Too Little Vitamin D
Health risks can results from lack of sunshine and vitamin-rich foods

(HealthDay News) -- Older adults who don't get enough sunshine or don't eat the right foods might suffer from a lack of vitamin D that could put them at risk.

Vitamin D plays a key role in bone health and muscle function, and many experts believe it also helps protect against diabetes, cancer, colds and tuberculosis.

A fat-soluble vitamin that is stored in the body's fatty tissue, vitamin D is produced naturally by the body through exposure to the sun. It also can be gotten from food and supplements.

According to the National Institutes of Health, the major biologic function of vitamin D is to maintain normal blood levels of calcium and phosphorus. By promoting calcium absorption, vitamin D helps to form and maintain strong bones. Vitamin D also works with other vitamins, minerals and hormones to promote bone mineralization. Without vitamin D, bones can become thin, brittle or misshapen. Vitamin D sufficiency prevents rickets in children and osteomalacia in adults, two forms of skeletal diseases that weaken bones.

About 25 percent of people older than 60 have low levels of vitamin D, say researchers.

Older adults are prone to low vitamin D levels, because they tend to spend less time in the sun and their skin is less efficient at producing vitamin D from sun exposure, said Denise Houston, an instructor in internal medicine-gerontology at Wake Forest University Baptist School of Medicine.

Older adults also may not get enough vitamin D from dietary sources, which include such dairy products as cheese, butter, cream and fortified milk along with fish, oysters, fortified cereals and margarine.

Without vitamin D, only 10 percent to 15 percent of dietary calcium and about 60 percent of phosphorus is absorbed by the body, which can have a direct effect on bone mineral density.

Houston led a team of researchers who analyzed data on 976 people 65 and older and found that those with low levels of vitamin D scored up to 10 percent lower on tests of physical performance and grip strength. The study found an association between vitamin D levels and physical performance, but the researchers said more study would be needed to prove that low levels actually caused poor performance.

By current recommendations, people age 50 to 69 should get 400 international units (IUs) of vitamin D every day, and people older than 70 should get 600 IUs a day. However, many experts believe that's not enough.

"Higher amounts of vitamin D may be needed for the preservation of muscle strength and physical function as well as other conditions such as cancer prevention," Houston said. "The current recommendations are based primarily on vitamin D's effects on bone health."

According to the National Institutes of Health, 10 to 15 minutes of sunshine three times a week is enough to produce the body's requirement of vitamin D.

On the Web

To learn more about vitamin D, visit the Web site of the National Institutes of Health, Office of Dietary Supplements.

SOURCES: HealthDay News ; Wake Forest University Baptist Medical Center , news release, April 23, 2007; Boston University , news release, July 18, 2007; National Institutes of Health, Office of Dietary Supplements (http://dietary-supplements.info.nih.gov)
Author: Anne Thompson
Publication Date: May 31, 2008
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