Vitamin D Status among Young Children Aged 1-3 Years: A Cross-Sectional Study in Wuxi, China

Background The increasingly recognized importance of vitamin D has been discussed and vitamin D status among young children has attracted widespread attention in recent years. However, study on vitamin D status in young children aged 1-3 y is limited in China. Objective To evaluate the nutritional vitamin D status of young children aged 1-3 y in Wuxi, southeastern China. Methods A large cohort of 5,571 young children aged 1-3 y were recruited in this study who visited the child health clinics at the Wuxi Maternity and Child Health Hospital (latitude 31.57 degrees N) during January 2014 to January 2015. Wuxi was located in southeastern China at a latitude of 31.57 degrees N. Finger-stick blood sampling was conducted in all the subjects and serum 25-Hydroxyvitamin D (25(OH) D) levels were measured to evaluate their vitamin D status. Results In this study, serum 25(OH) D levels of young children at the age of 1-3 years ranged from 20.6-132.9 nmol/L (Median: 71.5 nmol/L). 16.1% of the population had vitamin D deficiency (<50 nmol/L), while 38.8% of the subjects had a sufficient (50-74.9 nmol/L) vitamin D level. An optimal vitamin D status (>= 75 nmol/L) was found in 45.1% of the young children. The prevalence of vitamin D deficiency was higher in autumn (19.5%) than in summer (12.1%). There was no significant difference in vitamin D status between genders. The binary logistic regression analysis revealed that child age was strongly associated with vitamin D deficiency (adjusted OR: 1.173; 95% CI: 1.053-1.308; P = 0.004). Conclusions The prevalence of vitamin D deficiency was 16.1% among young children aged 1-3 y in Wuxi. Season and child age were associated with their vitamin D status. It is implied that young children should receive adequate amounts of vitamin D supplementation and spend more time outdoors to prolong the sunlight exposure when they grow older.