Adequate vitamin D supply may prevent mobility difficulties

Low blood vitamin D concentrations in older adults seem to increase the risk of developing mobility limitations and disability.

This observational study included 2,099 community-dwelling black and white men and women aged 70–79 who had no difficulty walking one-quarter of a mile, climbing 10 steps, or performing basic, daily living activities, and who were free of life-threatening illness (1). Vitamin D levels were measured in the blood at the beginning of the study and the occurrence of mobility limitation and disability was assessed every six months over the course of six years. The study results showed an approximately 30 percent increase in the risk of mobility limitations for the older adults who had low levels of vitamin D, and almost a twofold higher risk of mobility disability when compared with the participants with vitamin D levels over 75 nmol/L. 29% of participants had vitamin D blood levels below 50 nmol/L and 36% had 25(OH)D levels between 50 and
75 nmol/L.

The researchers commented that vitamin D plays an important role in muscle function, so it is plausible that low levels of the vitamin could result in the onset of decreased lower muscle strength and physical perfor-mance. Vitamin D may also indirectly affect physical function as low vitamin D levels have also been associated with diabetes, high blood pressure, and cardiovascular and lung disease – conditions that are frequent causes of decline in physical function. They added that it would be difficult to get enough vitamin D through dietary means alone and that older adults who did not spend much time outdoors would probably need to take a vitamin D supplement.

Current US recommendations call for people over age 70 to get 800 International Units of vitamin D in their diet or supplements daily. As the current dietary recommendations are based solely on vitamin D's effects on bone health, higher amounts of vitamin D may be needed for the preservation of muscle strength and physi-cal function, as well as other health conditions.

1. Houston D. K. et al. Low 25-Hydroxyvitamin D Predicts the Onset of Mobility Limitation and Disability in Community-Dwelling Older Adults: The Health ABC Study. Journal of Gerontology: Medical Sciences. Published online May 2012.