Low Serum 25-Hydroxyvitamin D as a Risk Factor for Frailty in Community-Dwelling Older Men: A Korean Nationwide Study

Despite the critical role of vitamin D in various biological processes, its impact on frailty-a condition closely linked to biological age-remains inconclusive. This study aimed to explore the association between serum 25-hydroxyvitamin D (25[OH] D) levels and frailty status in older Korean adults, utilizing a comprehensive frailty index (FI) and a nationally representative dataset.

This cross-sectional study included 6,589 participants aged ≥65 years from the Korea National Health and Nutrition Examination Survey (2008-2012). Frailty was assessed using a deficit accumulation FI based on 38 physical, cognitive, psychological, and social items.

After adjusting for potential confounders, frail men showed 6.8% lower serum 25(OH)D concentrations compared to nonfrail controls (P=0.007). Men in the lowest serum 25(OH)D quartile (≤39.3 nmol/L) exhibited a 5.3% higher FI (P=0.047) and 1.71-fold increased odds of frailty (P=0.005), compared to those in the highest quartile (>63.3 nmol/L). Similarly, men with vitamin D deficiency (<30 nmol/L) exhibited a 9.6% higher FI compared to those with sufficient vitamin D levels (≥50 nmol/L; P=0.004). However, no significant association between serum 25(OH)D concentration and frailty was observed in women across any analysis.

These findings suggest that low serum 25(OH)D concentrations are a potential risk factor for frailty, particularly in men. Further research is warranted to determine whether vitamin D supplementation in such high-risk older adults could help mitigate frailty.