Older people with higher blood levels of vitamin D are able to walk and rise from a chair faster than those who have lower vitamin D levels, according to a study reported in the American Journal of Clinical Nutrition.
In the study, 4,100 adults over age 60 were asked to complete two separate tasks to measure physical function. Participants completed an eight-foot walking speed test (eight-foot-walk test) and a timed test of five repetitions of rising from a chair and sitting down (sit-to-stand test).
Those who walked at least one mile, swam, jogged, rode a bike, danced, or did garden work in the previous month were considered “active,” while those who did none of these activities were classified as “inactive.” Blood levels of 25-hydroxyvitamin D (the most reliable test for vitamin D nutritional status) were measured in all participants and divided into five quintiles, ranging from lowest to highest.
People with the highest blood levels of vitamin D were able to complete the eight-foot-walk test and sit-to-stand test faster than those with the lowest blood levels of vitamin D. Although active participants were quicker in completing the tests than the inactive group, the difference in performance speed between the two groups decreased as the level of vitamin D increased, which suggests that vitamin D helps improve muscle function, independent of physical activity. Even a modest increase in vitamin D levels was associated with improvement in both tests; however, the best performance was observed in those whose levels were in the highest quintile.
American Journal of Clinical Nutrition 80(3):752-758, 2004