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Vitamin D Picture Could Be Sunnier For Elders
By Judy McBride
July 8, 1998
Vitamin D status is better for elderly men and women in the general population than for elderly hospital patients, according to findings from a study funded by the National Institutes of Health and USDA's Agricultural Research Service. But the study suggests inadequate D is an important public health problem in older Americans.
Researchers with USDA's Human Nutrition Research Center on Aging at Tufts in Boston and the Framingham, Mass., Heart Study conducted the first population-based study of vitamin D with 759 free-living volunteers, age 67 to 95. Epidemiologist Paul Jacques led the study.
About 15 percent of the women and 6 percent of the men had low blood levels of 25- hydroxyvitamin D--the major circulating form of vitamin D and the most sensitive measure of D status. About 4 percent of the women and 2 percent of the men were deficient.
Vitamin D is essential for healthy bones and teeth and helps prevent osteoporosis. Milk is fortified with the vitamin, as are some breakfast cereals. Fatty fish, egg yolks, liver, cheese and butter are naturally rich sources. Sunlight stimulates skin to manufacture the vitamin. The study data confirm the importance of eating foods rich in vitamin D and exposing skin to sunlight.
Participants' blood levels of D rose in step with intakes, leveling off only for men after daily intakes reached 400 International Units--twice the Recommended Dietary Allowance. Two-thirds of the volunteers drank less than 8 ounces of milk daily, which would supply half the RDA. Vitamin D supplements were a significant factor for the women's status, but were not as significant for the men's. Only 25 percent of the women and 20 percent of the men took vitamin D supplements.
Vitamin D levels were highest in late summer--after months of long, sunny days--and lowest in late winter. Low D status was inversely associated with time outdoors. Other study data suggest that older men may have a greater capacity to make vitamin D than older women.
Scientific contact: Paul F. Jacques, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts, Boston, MA 02111, phone (617) 556-3320, fax (617) 556-3344, paul@hnrc.tufts.edu.
