ARS | Publication request: HIGHER 25-HYDROXYVITAMIN D LEVELS ARE ASSOCIATED WITH BETTER LOWER EXTREMITY FUNCTION IN BOTH ACTIVE AND INACTIVE ADULTS 60+ YEARS OF AGE

Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 8, 2004
Publication Date: September 1, 2004
Citation: Bischoff-Ferrari, H.A., Dietrich, T., Orav, J.E., Hu, F.B., Zhang, Y., Karlson, E., Dawson-Hughes, B. 2004. Higher 25-hydroxyvitamin D levels are associated with better lower extremity function in both active and inactive adults 60+ years of age. American Journal of Clinical Nutrition. 80:752-758.

Interpretive Summary: Complications caused by falls are the leading cause of death from injury in men and women over age 65. It has been suggested that vitamin D treatment in the elderly could improve musculoskeletal function thereby reducing their risk of falling. This study looks at the association between 25-hydroxyvitamin D (25-OHD) levels and lower extremity function in ambulatory elderly, whether the association differs by activity level and whether there is an identifiable threshold in this association. Linear regression analyses and regression plots were used to assess functional performance by serum 25-OHD levels in a cross-sectional, representative sample of the US population (NHANES III; 4100 adults age 60-90+ years). Among the factors taken into consideration were activity level (inactive vs. active), walking speed, and sit-to-stand speed. In comparison to the group with the lowest 25-OHD levels, the highest-level group showed an improvement in walking speed and in sit-to-stand speed. Active subjects were quicker in both tests than inactive subjects, but the same improvement in performance speed at higher 25-OHD levels was found in active and inactive subjects. Within the 25-OHD reference range of 22.5 to 94 nmol/L, levels above 40 nmol/L and as high as 90 nmol/L were associated with better musculoskeletal function in the lower extremities. This suggests that much of the older American population will benefit from supplementation with vitamin D.

Technical Abstract: It has been suggested that vitamin D treatment improves musculoskeletal function and reduces the risk of falling in institutionalized elderly individuals. The aims of this study were to determine whether there is an association between 25-hydroxyvitamin D (25-OHD) levels and lower-extremity function in ambulatory older persons, and, if so, whether the association differs by activity level and whether there is an identifiable threshold in this association. A cross-sectional, population-based sample of the US ambulatory population age 60-90+ years (the Third National Health and Nutrition Examination Survey; NHANES III; 4100 adults) was used. Linear regression analyses and regression plots were used to assess lower extremity functional performance by 25-OHD serum levels controlling for sex, age, race/ethnicity, BMI, calcium intake, poverty income ratio, number of medical comorbidity, self-reported arthritis, use of a walking device, month of measurement and activity level (inactive vs. active and METs in active elderly). In both active and inactive ambulatory individuals age 60 and older, 25-OHD levels above 40nmol/l and as high as 90 nmol/l, the upper end of the reference range, are associated with better musculoskeletal function in the lower extremities.