So getting enough of the vitamin is important, according to lead author Denise Houston, Ph.D.
It has been shown that older adults "had lower rates of falls and also some improvement in muscle strength" when they have sufficient vitamin D, Houston told All Headline News (AHN) in an interview.
But about 12 million people, or 25 percent of those over 60 are low in vitamin D and it is difficult to get enough through diet alone, said Houston, an instructor in internal medicine - gerontology.
Although Vitamin D is naturally produced when skin is exposed to the sun's ultraviolet rays, older adults often aren't out in the sun long enough and people's skin becomes less efficient at synthesizing sunlight into vitamin D with age, researchers say.
Foods such as fortified milk, juice and cereals also contain vitamin D, but it is hard to get the recommended 400 international units of vitamin D that way. Houston says that unless people drink milk they are unlikely to get it.
But people can take supplements and researchers found that higher amounts might be needed and studies show that doses up to 10,000 IUs have no negative effect, Houston said.
For supplementation, Houston says to make sure to look on the label and see that it says vitamin D3 because it is the "more bio available" of the vitamin D forms, and will convert into an active form that the body can absorb and use. Houston said that a lot of the D2 form was not as available to the body.
Since they have found that a lack of the vitamin can cause poor physical performance and disability, the next step is to do a study giving people supplements of vitamin D to "see if we intervene if we would see physical improvement in muscle and performance," Houston said.
Previous research has shown that vitamin D protects not just bone health, but also possibly protects individuals against such things as diabetes, cancer, colds and tuberculosis.
The study is published in the April issue of the Journal of Gerontology: Medical Sciences.
