So say British researchers who found quarterly supplements of vitamin D could reduce the overall risk of fractures in people over 65 by 22 percent. The risk of fracture at common sites, such as the hip, wrist, forearms or back, was reduced by 33 percent with vitamin D supplementation.
"Maintaining adequate vitamin D status can reduce the risk of fractures," says study author Kay Tee Khaw, a professor of clinical gerontology at the University of Cambridge School of Clinical Medicine.
However, Khaw cautions, too much vitamin D can be toxic and recommends that no one take more than 800 IUs of vitamin D a day without consulting their physician first.
The study appears in the March 1 issue of the British Medical Journal.
Vitamin D is known as the "sunshine vitamin" because your body manufactures it when it's exposed to the sun. Vitamin D is also found in enriched dairy products, fatty fish and fish oils, as well as supplements. A lack of vitamin D can cause weak bones and contribute to the development of osteoporosis.
Older people are more at risk for vitamin D deficiencies because the body doesn't produce vitamin D as efficiently with age, and the elderly often spend more time indoors, away from the sun.
Khaw and his colleagues recruited 2,686 people between 65 and 85 years old for this study. Slightly more than 2,000 of the participants were men. All were still living in a community, not in a nursing home.
For five years, the researchers sent half of the volunteers one slow-release vitamin D capsule, containing 100,000 IUs of vitamin D3, by mail every four months. The other half of the group received a placebo capsule every four months. They were told to take the capsule immediately and to complete a short survey about their health.
The researchers also took a blood sample from 235 of the participants after four years to measure the vitamin D levels in their blood.
They found the volunteers who took the vitamin D supplements had a significantly lower rate of fractures. Fractures at common sites were reduced by one-third and overall by almost one-quarter.
"The results of the study are impressive," says Dr. Khaled Imam, a geriatric medicine specialist at William Beaumont Hospital in Royal Oak, Mich. He says the study is interesting because it included more men than women and because of the high doses of vitamin D given.
Imam explains most studies on osteoporosis focus on women, but that among the elderly, it is a serious problem for men as well.
While the dose of vitamin D given was in a slow-release form, Imam says he is concerned about what effect such a high dose might have on people with medical problems, such as kidney disease. One limitation of the study, according to Imam, is that the researchers didn't take more frequent blood samples to measure the concentrations of vitamin D at different points in the study.
He recommends that both men and women over 65 should get between 400 and 800 IUs of vitamin D a day, and at least 1,200 milligrams of calcium daily.