Vitamin D status among the elderly Chinese population: a cross-sectional analysis of the 2010-2013 China national nutrition and health survey (CNNHS).

backgroundVitamin D inadequacy is common among the elderly, especially within the Asian population. The vitamin D status among healthy adults in the elderly Chinese population was evaluated.

methodsA total of 6014 healthy adults aged 60 years or older (2948 men, 3066 women) participated in this descriptive cross-sectional analysis. Possible predictors of vitamin D inadequacy were evaluated via multiple logistic regression analyses.

resultsThe median serum 25-hydroxyvitamin D (25(OH)D) levels were 61.0 nmol/l (interquartile range (IQR) 44.3-80.6, range 5.1-154.5) for men and 53.7 nmol/l (IQR 38.8-71.0, range 6.0-190.0) for women, with 34.1% (95% confidence interval (CI) 32.4-35.8) of men and 44.0% (95% CI 42.2-45.8) of women presenting vitamin D inadequacy (25(OH)D <50 nmol/l). According to the multivariate logistic regression analyses, vitamin D inadequacy was positively correlated with female gender (P <0.0001), underweight (P = 0.0259), the spring season (P <0.0001), low ambient UVB levels (P <0.0001) and living in large cities (P = 0.0026). For men, vitamin D inadequacy was positively correlated with the spring season (P = 0.0015), low ambient UVB levels (P <0.0001) and living in large cities (P = 0.0022); for women, vitamin D inadequacy was positively correlated with the spring season (P = 0.0005) and low ambient UVB levels (P <.0001).

conclusionsVitamin D inadequacy is prevalent among the elderly population in China. Because residing in regions with low ambient UVB levels increases the risk of vitamin D inadequacy both for men and women, vitamin D supplementation and sensible sun exposure should be encouraged, especially during the cooler seasons. Further studies are required to determine the optimal vitamin D intake and sun exposure levels to maintain sufficient vitamin D levels in the elderly Chinese population.