Associations Between Vitamin D Deficiency and Sarcopenia in South Korean Adults: Based on the 2022 Korea National Health and Nutrition Examination Survey.

Background/Objectives: Although vitamin D has been associated with sarcopenia in older adults, evidence across age groups remains limited. This study evaluated the relationship between vitamin D deficiency (VDD) and muscle health in Korean adults aged ≥19 years. Methods: Data utilized in this study were obtained from the 2022 Korea National Health and Nutrition Examination Survey IX-1. Serum 25-hydroxyvitamin D [25(OH)D] levels were analyzed in relation to appendicular skeletal muscle mass (ASM), grip strength, and sarcopenia using multivariable regression models. Results: Among 3,920 participants, 46.5% had VDD, with the highest prevalence observed in younger adults. After adjusting for age, body mass index, energy intake, and other confounding factors, serum 25(OH)D levels showed a positive association with ASM in middle-aged men (β = 0.005; p = 0.007) and with maximal handgrip strength in young men (β = 0.097; p = 0.048). Among older men, those with VDD had significantly higher odds of low muscle mass (OR = 1.82; 95% CI: 1.10-3.02) and sarcopenia (OR = 2.30; 95% CI: 1.03-5.16) than those without VDD, after adjusting for potential confounders. No significant associations were observed in women. Conclusions: These results suggest that maintaining adequate vitamin D levels may benefit muscle health in men. Further prospective or interventional studies are needed to more accurately assess the effects of vitamin D on muscle health.