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 who were 65 years and older from two towns in the Chianti area of Italy. The mean age of participants was 74.8 years. Data were collected from Sept. 1998 through March 2000.
Participants completed a short physical performance test of their walking speed, ability to stand 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 using a hand-held dynamometer.
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.
The study wasn’t designed to evaluate whether low vitamin D levels actually cause poor physical performance, but the results suggest the need for additional research in this area, said Houston. She said vitamin D plays an important role in muscle function, so it is plausible that low levels of the vitamin could result in lower muscle strength and physical performance.
“But it’s also possible that those with poor physical performance had less exposure to sunlight resulting in low vitamin D levels,” she said.
Current recommended daily intake for vitamin D might be too low.
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, suggest 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.”
We spend less time outside than our ancestors did. It seems likely we do not make enough vitamin D from sun exposure. At the same time, many of us do not get much vitamin D from foods. So vitamin D deficiency might be common.
|Share |||Randall Parker, 2007 April 25 10:59 PM Aging Diet Studies|