Vitamin D status and lower extremity function: the Health ABC Study

Abstract

Vitamin D insufficiency is common among older adults and may play a role in physical function. Few studies have examined the longitudinal association between vitamin D status and physical function. We examined the association between baseline serum 25‐hydroxyvitamin D (25[OH]D) and lower extremity function (LEF) at baseline, 2‐ and 4‐yrs in well‐functioning older adults in the Health ABC Study (n=2,788). LEF was assessed using the Health ABC expanded short physical performance battery (Health ABC SPPB, range 0–4), 400‐m walk test, and isokinetic knee strength. Mixed models were used to examine the associations between 25(OH)D status (<50, 50–75, and 75 nmol/L) and LEF adjusted for age, gender, race, education, field site, and season. Participant mean age was 74.7 yrs; 51.1% were women, 39.7% were black, and 31.7% had 25(OH)D 75 nmol/L. Compared to individuals with 25(OH)D <50 nmol/L, those with 25(OH)D 75 nmol/L had 0.17 (SE=0.03) higher Health ABC SPPB scores (p<0.0001) and 0.09 (SE=0.01) m/sec faster gait speed on the 400‐m walk test (p<0.0001) across all 3 time points, but had similar knee strength (p=0.79). Although LEF declined over time (p<0.0001 for all), the interaction between vitamin D status and time was not significant. In summary, vitamin D insufficiency is associated with lower extremity function but not with greater declines in lower extremity function over 4 years of follow‐up. NIA, R01 AG029364.