NMA: Nonprescription Medicines Academy

Vitamin D Supplementation May Reduce the Burden of Mobility Disability in Older Adults

August 1st, 2012

Data from the Health, Aging, and Body Composition (Health ABC) study suggest that low serum 25-hydroxyvitamin D [25(OH)D] concentrations are associated with an increased risk of mobility limitation and disability in older adults.

Health ABC is a prospective cohort study investigating the associations between body composition, weight-related health conditions, and incident functional limitations in community-dwelling white and black men and women 70 to 79 years of age in the Pittsburgh (Pennsylvania) and Memphis (Tennessee) metropolitan areas. The primary objective of the current analysis was to examine the association between 25(OH)D and incident mobility limitation and disability over 6 years of study follow-up. Possible effects of parathyroid hormone (PTH) on incident mobility limitation and disability also were examined. Mobility limitation and disability were assessed during annual clinic visits alternating with telephone interviews every 6 months throughout the study; serum 25(OH)D and PTH levels were measured at the Year 2 clinic visit. Mobility limitation was defined as two consecutive reports of having any difficulty walking 0.25 mile or climbing 10 steps, while disability was defined as two consecutive reports of having severe difficulty performing these tasks.

The final analysis sample included 2,099 participants. At the Year 2 visit, 28.9% of the participants had a serum 25(OH)D concentration <50 nmol/L (equivalent to <20 ng/mL), and 36.1% had a serum 25(OH)D concentration of 50 to <75 nmol/L. Over 6 years of follow-up, 738 participants (36.3%) reported having mobility limitation and 245 (22.0%) reported having mobility disability. Participants with lower serum 25(OH)D concentrations were at greater risk of developing mobility limitation and mobility disability, compared with the 35.0% of participants who had a serum 25(OH)D concentration ≥75 nmol/L. The hazard ratios (HR) of incident mobility limitation and mobility disability by 25(OH)D category—after adjusting for demographics, health behaviors, and chronic conditions—were as follows:

  • Mobility limitation with 25(OH)D <50 nmol/L: HR 1.29 (95% CI, 1.04–1.61).
  • Mobility limitation with 25(OH)D 50 nmol/L to <75 nmol/L: HR 1.27 (95% CI, 1.05–1.53).
  • Mobility disability with 25(OH)D <50 nmol/L: HR 1.93 (95% CI, 1.32–2.81).
  • Mobility disability with 25(OH)D 50 nmol/L to <75 nmol/L: HR 1.30 (95% CI, 0.92–1.83).

In contrast, elevated PTH was not significantly associated with developing mobility limitation or disability.

The authors concluded that prevention or treatment of low serum 25(OH)D concentrations may provide a pathway for reducing the burden of mobility disability in older adults.

J Gerontol A Biol Sci Med Sci. 2012 May 9. [Epub ahead of print]