Recent research has led to a growing awareness of the importance of vitamin D to our overall health. We all need vitamin D, which we get mainly through diet or through exposure to sunlight.
Because the elderly often eat poorly and spend much of their time inside, however, many do not get enough vitamin D and put themselves at increased risk for premature frailty and disability, according to a new study.
"With a growing older population, we need to identify better ways to reduce the risk of disability," said lead author Denise Houston, Ph.D, of the Wake Forest University School of Medicine. "Our study showed a significant relationship between low vitamin D levels in older adults and poorer physical performance."
About one-fourth of people over age 60 have low vitamin D levels. Previous research has shown that vitamin D not only plays a role in bone health, but possibly also in protecting against diabetes, cancer, colds and tuberculosis.
"Recent findings showing the importance of vitamin D status on multiple health outcomes underscore the need for more research on the effects of low vitamin D levels in elderly populations," said Houston.
Vitamin D is naturally produced when skin is exposed to the sun's ultraviolet rays. Foods such as fortified milk, juice and cereals also contain vitamin D, but it is difficult to get enough through diet alone, said Houston.
Older adults are particularly prone to low vitamin D levels both because they may get less exposure to sunlight and because their skin is less efficient in producing vitamin D than that of younger adults.
For the current study, researchers analyzed data from the InCHIANTI study, which evaluated factors contributing to the decline of mobility in late life. The study involved 976 people 65 and older from northern Italy. They completed a short test of their walking speed, ability to get up from a chair and ability to maintain their balance in progressively more challenging positions. In addition, handgrip strength, a predictor of future disability, was measured.
The researchers found that physical performance and grip strength were about five to 10 percent lower in those who had low levels of vitamin D. After looking at other variables that could influence the results, such as body mass index, physical activity, the season of the year, mental abilities, health conditions and anemia, the results held true.
Current recommendations call for people from age 50 to 69 to get 400 international units (IUs) of vitamin D per day and for those over age 70 to get 600 IUs. Many researchers, however, feel that higher amounts may be needed.
"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," said Houston. "The current recommendations are based primarily on vitamin D's effects on bone health."
The results of this study are reported in the April 2007 issue of the Journal of Gerontology: Medical Sciences.