Vitamin D status and related factors in adolescent in Fuyang

Objective The purpose of this study was to determine vitamin D status in adolescents in North Anhui and to examine factors that independently related vitamin D status.Methods In April 2015,a total of 339 adolescent were selected from six classes in a college in Fuyang,one of the largest cities in North Anhui located at 32.9 degrees north latitude.Concentrations of 25(OH) D in finger-tip blood was measured by using LC-MS/MS,and questionnaires were used to collect information on related factors.Results The mean 25(OH) D level was 16.0 nmol/L(SD=5.4),ranged from 6.2 to 34.5.Univariate analysis indicated that the concentration of 25(OH) D was higher in adolescents with younger age,female,non-only child,longer duration of sun exposure,outdoor activities more than 30 minutes between 11 am and 15 pm in a nearly week,light-skin and non-drinking.However,there was no significant association between intake frequencies of vitamin D-rich food and 25(OH) D level.In a multiple linear regression model,25(OH) D levels significantly decrease with the increase of the age (β=-0.62,95%Cl=-1.04-0.20);25(OH) D level of girls were significant higher than boys(β =2.31,95%Cl =0.96-3.66);and 25(OH) D level was significantly elevate with the increase of sun exposure frequency(β=0.99,95%CI=0.13-1.85) and outdoor activity time between 11 am and 15 pm(β=0.93,95%CI=0.27-1.58).Conclusions Vitamin D deficiency among adolescents in North Anhui is common.More frequencies of sun exposure and increasing time of outdoor activity,rather than more vitamin D rich food,might significantly improve vitamin D levels.