Abstract
OBJECTIVES: This study aimed to explore the association of circulating vitamin D levels with incidence of sarcopenia and its diagnostic components in older men and women. DESIGN: Two-year longitudinal study. SETTING: Nationwide Korean Frailty and Aging Cohort Study. PARTICIPANTS: A total of 1,292 adults (53% women) aged 70-84 years without sarcopenia at baseline and who completed the 2-year follow-up sarcopenia assessment were included. MEASUREMENTS: Serum 25-hydroxyvitamin D [25(OH)D] concentrations were measured using a chemiluminescent immunoassay and categorized into sex- and blood collection period-specific quartiles. The appendicular skeletal muscle mass was assessed using dual-energy X-ray absorptiometry. Muscle strength was evaluated using handgrip strength, and physical performance was assessed using the five-times-sit-to-stand test, usual gait speed, and Short Physical Performance Battery. Sarcopenia was defined in accordance with the 2019 consensus of the Asian Working Group for Sarcopenia. Logistic regression and generalized linear models were used to assess the association of serum 25(OH)D concentrations with sarcopenia and its components. RESULTS: Over the 2-year follow-up, incident sarcopenia occurred in 15.7% of men and 12.1% of women. Serum 25(OH)D concentrations were inversely associated with incident sarcopenia in men (odds ratio [OR] for the highest vs. lowest quartile, 0.47; 95% confidence interval [CI], 0.23-0.94; P for trend = 0.03), whereas no significant association was observed in women. When examining the association between serum 25(OH)D concentrations and components of sarcopenia, the third quartile was associated with lower odds of low muscle mass in men (OR, 0.39; 95% CI, 0.20-0.77) and low physical performance in women (OR, 0.32; 95% CI, 0.15-0.68), compared to the first quartile. Additionally, higher serum 25(OH)D concentrations were associated with more favorable annual changes in usual gait speed in men but not in women. CONCLUSION: Low serum 25(OH)D concentrations are associated with a higher likelihood of incident sarcopenia and its components, particularly among men. Adequate 25(OH)D concentrations may help slow age-related decline in muscle mass and function, with potential sex differences.