Vitamin D status and physical function in older Finnish people: A one-year follow-up study

The aim was to describe vitamin D status and its association with changes in PF during 12 months in Finnish community-dwelling elderly (≥65 years).

Baseline serum 25-hydroxyvitamin D (25OHD) concentration was measured by enzymeimmunoassay, and participants (n=518) were divided according to 25OHD to three groups (I <50 nmol/l, II 50-74.9 nmol/l, and III ≥75 nmol/l). PF (maximal isometric extension strength of right and left knee, and time in five-repetition sit-to-stand test (5STS) and 10-m walking test) was measured at baseline and after 12 months. 25OHD deficiency (<50 nmol/l) was found in 20.5% of the participants. During a 12-month follow-up, differences in changes in knee extensor strength of right (p=0.044) and left (p=0.010) lower extremity and in 10-m walking test (p=.040) between the groups were significant. According to further pairwise comparisons these differences were between groups I and III (right knee, p=0.036; left knee, p=0.009; 10-m walk, p=0.044), with the exception of left knee extensor strength in which there were also significant difference between groups I and II (p=0.039). All significant differences in changes were in favour of group II or III. Significant differences in changes in knee extensor strengths maintained after adjustments for group (intervention/control), parathyroid hormone, and baseline level of knee extensor strength.

Prospective analyses showed low 25OHD concentrations (<50 nmol/l) to be associated with deterioration in PF during 12 months compared with high 25OHD concentrations (≥75 nmol/l).