Poor Vitamin D Status Is Prospectively Associated with Greater Muscle Mass Loss in Middle-Aged and Elderly Chinese Individuals

Background Poor vitamin D status can increase age-related muscle mass loss. However, existing prospective evidence is limited and controversial. Objective This study aimed to investigate the association of plasma 25-hydroxyvitamin D [25(OH)D] with muscle mass loss in middle-aged and elderly Chinese individuals over 6 years. Design We conducted a prospective cohort study. Participants/setting This community-based study included 568 men and women aged 50 to 70 years at baseline. Main outcomes measures Baseline plasma concentrations of 25(OH)D and biomarkers of liver and kidney functions and inflammation were measured. Body composition was assessed at baseline and 6-year follow-up by dual-energy x-ray absorptiometry. Appendicular skeletal muscle mass (ASMM) and trunk lean mass were calculated and total body lean mass was defined as an overall measure of total nonfat and nonbone tissues. Statistical analyses performed Descriptive statistics and multiple linear regression were applied. Results The 6-year loss of ASMM was 1.14 kg (5.3%) in men and 0.47 kg (3.1%) in women (all P values <0.001). Compared with the highest 25(OH)D tertile, participants in the lowest tertile had significantly more absolute loss of ASMM (-1.21 vs -1.00 kg; P for trend=0.024) after multivariate adjustments for conventional confounders, as well as protein intake. The association persisted after additional adjustment of bone mineral density and inflammatory markers (P for trend=0.017). No significant associations were detected between 25(OH)D and absolute loss of trunk lean mass or total body lean mass. Conclusions Lower 25(OH)D concentrations were prospectively associated with greater ASMM loss in middle-aged and elderly Chinese individuals independent of bone mineral density, inflammation, diet, and other risk factors.