[Multilevel study on the effects of dietary nutrients on body mass index of Chinese children and adolescents aged 7-17].

OBJECTIVE:Analyze the relationship between dietary nutrients and body mass index of children and adolescents aged 7-17 in China. METHODS:The data comes from the "China Health and Nutrition Survey", and 5562 children and adolescents aged 7-17 who participated in at least one round(2000, 2006, 2011 and 2015) of the survey and had complete dietary and physical measurement survey data were selected as the research objects. A three-level(community-individual-observation level) linear random intercept mixed effect model of body mass index was constructed to analyze the influence of dietary nutrient intake of children and adolescents of different genders in urban and rural areas on their body mass index(BMI).24 hours for 3 consecutive days and family weight accounting were used to evaluate the dietary nutrient intake. RESULTS:BMI of urban children and adolescents is higher than that of rural children and adolescents. The BMI of children and adolescents aged 12-17 is higher than that of children and adolescents aged 7-11. BMI of boys was higher than that of girls, but the difference was statistically significant only in 2011 and 2015. After controlling for confounding factors such as individual level(survey year, age, physical activity and family per capita income) and community level(community urbanization index), the three-level model showed that the BMI of rural boys increased with the increase of cholesterol intake(P<0.01). BMI of urban girls increased with the increase of vitamin B_1 intake(P<0.05) and iron intake(P<0.01). BMI of rural girls increased with the increase of vitamin E intake(P<0.001) and sodium intake(P<0.05). CONCLUSION:There are some differences in dietary nutrients that affect the BMI level of 7-17 years old children and adolescents between urban and rural areas.