Vitamin D May Have Role in Mobility Disabilities

Vitamin D, that little nutrient found in milk and developed by exposure to the sun, might be key to preventing mobility impairments, according to new research from Wake Forest Baptist Medical Center.

The study, published in the Journal of Gerontology: Medical Sciences, analyzed the association between vitamin D and the onset of mobility limitation and disability over six years of follow-up using data from the National Institute on Aging’s Health, Aging and Body Composition (Health ABC) study. The researchers defined mobility limitation and disability as any difficulty or inability to walk several blocks or climb a flight of stairs.

“We observed about a 30-percent increased risk of mobility limitations for those older adults who had low levels of vitamin D, and almost a two-fold higher risk of mobility disability,” said Dr. Denise Houston, a nutrition epidemiologist in the Wake Forest Baptist Department of Geriatrics and Gerontology.

Vitamin D plays an important role in muscle function, Houston explained. Therefore, low levels of the vitamin could cause decreased lower muscle strength and physical performance. Because vitamin D has been associated with diabetes, high blood pressure, cardiovascular disease and lung disease—conditions that cause decline in physical function—low levels of the vitamin might also indirectly affect physical function.

To get enough vitamin D, people can eat foods such as fortified milk, juice and cereals; get moderate sun exposure; or take supplements. People older than 70 require 800 International Units of vitamin D daily, although higher amounts might be necessary to prevent loss of muscle strength and physical function, Houston said.

Data from 2,099 men and women age 70-79 were collected in the study. Eligible participants reported no difficulty walking one-fourth mile, climbing 10 steps, or performing basic, daily living activities, and had no life-threatening illness. Vitamin D levels were measured in the blood at the beginning of the study. Annual clinic visits alternating with telephone interviews were used to assess the occurrence of mobility limitation and disability every six months over six years.