Associations of Serum Vitamin D Level with Sarcopenia, Non-Alcoholic Fatty Liver Disease (NAFLD), and Sarcopenia in NAFLD Among People Aged 50 Years and Older: The Korea National Health and Nutrition Examination Survey IV-V.

Background: The role of serum 25-hydroxyvitamin D [25(OH)D] levels in the development of sarcopenia in non-alcoholic fatty liver disease (NAFLD) remains controversial. We investigated the association between vitamin D levels, occurrence of sarcopenia, NAFLD, and sarcopenia in NAFLD in adults aged >50 years. Methods: This study used data pertaining to 5396 adults aged >50 years (1870 men and 3526 women) from the 2008-2011 Korea National Health and Nutrition Examination Survey. Appendicular skeletal muscle mass adjusted by weight (ASM/Wt) was used to diagnose sarcopenia, and NAFLD was diagnosed using the NAFLD fat score. Results: The lowest quintile of serum 25(OH)D level (4.85-15.26 ng/mL) was associated with an increased occurrence of sarcopenia [odds ratio (OR) 2.65; 95% confidence interval (CI) 1.64-4.27], NAFLD (OR 1.82; 95% CI 1.19-2.96), and sarcopenia in NAFLD (OR 2.25; 95% CI 1.26-4.03) in men. In women, sarcopenia (OR 1.80; 95% CI 1.29-2.51) was also significantly associated with serum vitamin D levels, whereas high levels of vitamin D were not significantly related to NAFLD. Conclusions: Serum vitamin D levels are associated with sarcopenia, NAFLD, and sarcopenia in NAFLD. Vitamin D level can be a useful marker of sarcopenia and NAFLD, especially in men.