High prevalence of vitamin D deficiency and influencing factors among urban and rural residents in Tianjin, China

Summary There was a high prevalence of vitamin D deficiency among residents in Tianjin, China, especially among female residents, rural young adults, and elderly individuals. This is the first large-scale study evaluating vitamin D status in Tianjin, China, and we believe that it makes a significant contribution to the literature. Purpose Vitamin D deficiency has been documented as a worldwide public health problem. To our knowledge, there has not been any large-scale study on vitamin D status in Tianjin, China. The aim of this study was to investigate vitamin D status among Tianjin residents and to determine influencing factors. Methods This is a community-based study, and residents from both urban and rural areas of Tianjin were enrolled. Each participant completed a questionnaire regarding basic characteristics and lifestyle information. Serum 25-hydroxyvitamin D [25(OH)D] levels were statistically analyzed according to sex, age, and region. Other factors associated with vitamin D deficiency were also explored. Results A total of 1814 participants were included, with mean serum 25(OH)D level of 49.44 ± 14.9 nmol/L; only 47.63% achieved the optimal (50–125 nmol/L) 25(OH)D level. Serum 25(OH)D levels were higher among male participants than among female participants (53.44 ± 13.94 versus 46.55 ± 14.91 nmol/L, P < 0.05) and among urban participants than among rural participants (50.4 ± 16.32 versus 48.65 ± 13.58 nmol/L, P < 0.05). Serum 25(OH)D levels were significantly higher among the age group of 40–49 years (50.7 ± 17.99 nmol/L) than among the ≥ 70 years (48.45 ± 14.49 nmol/L) or 18–29 years (47.81 ± 13.08 nmol/L) age groups. Conclusions There was a high prevalence of vitamin D deficiency/inadequacy among Tianjin residents, especially among female participants, rural young adults, and elderly individuals. Vitamin D supplementation is imperative for these high-risk vitamin D-deficient residents.