[Nutritional status and influence of vitamin D among Chinese lactating women in 2013]

Objective: To analyze serum vitamin D levels in Chinese lactating women, in 2013, and to evaluate their vitamin D nutritional status and influencing factors. Methods: Data were from the Chinese National Nutrition and Health Surveillance in 2013. Using the multistage stratified cluster sampling method, serum samples from lactating women, at 0-24 months postpartum, were obtained from 55 sites in 30 provinces of China, excluding the Tibet Autonomous Region. The concentration of serum vitamin D was determined by mass spectroscopy. A standard questionnaire was used to obtain basic information and the season of blood collection. Dietary information for one recent month was collected using a food frequency questionnaire. A total of 1 981 lactating women were included in the study. A multiple logistic regression model was used to analyze the factors related to vitamin D levels among lactating women. Results: The mean vitamin D level was (16.6±6.5) ng/ml, the prevalence of vitamin D deficiency (VDD) (vitamin D<12 ng/ml) was 25.2% (499 cases) and the prevalence of vitamin D inadequacy (12 ng/ml≤vitamin D<20 ng/ml) was 45.4% (900 cases). Compared with in the Han ethnic group, the OR value of VDD was 13.37 for Muslim ethnic women. Compared with women having a junior high school education or below, the OR value of VDD was 1.40 for those women with an educational level of senior high, middle school or above. Compared with housewives or nonworking women, the OR value of VDD was 1.62 for professional women. Compared with women living in general rural settings, the OR values of VDD for women living in large cities, medium and small cities or poor rural settings were 1.99, 1.46 and 2.66 respectively. Compared with the women surveyed in the fall, the OR value of VDD was 2.19 for the women surveyed in winter or spring. The VDD prevalence increased with higher latitude (OR=1.12) and decreased with increased meat consumption per day (OR= 0.73). (P<0.05 for all comparisons). Conclusion: Vitamin D deficiency and vitamin D inadequacy were common in lactating women in China. Those with increased risk of VDD included lactating women who were ethnic Muslims, with higher education levels, engaged in a professional occupation, living in higher latitude region and were surveyed in winter and spring.