Dairy consumption and pre-school, school-age and adolescent obesity in developed countries: a systematic review and meta-analysis.

Childhood obesity, the primary health problem affecting children in developed countries, has been attributed in part to changes in dietary patterns. Secular trends suggest a decrease in childhood dairy consumption coinciding with the rise in obesity prevalence. The objective of the present systematic review and meta-analysis was to consider evidence of associations between dairy intake and adiposity in pre-schoolers, school-age children and adolescents in developed countries. Of 36 studies included in the systematic review, sufficient data for effect size estimation and inclusion in the meta-analysis were obtained from 22 studies. No significant association was found between dairy intake and adiposity in the aggregated data, although statistical heterogeneity was high (I(2) = 0.72). Among adolescents, however, dairy intake was inversely associated with adiposity (effect size -0.26, [-0.38, -0.14], P < 0.0001). Effect size was not predicted by exposure variable (milk vs. dairy), study design, statistical methods, outcome variables or sex. Interpretation of results was complicated by variability in study methods and insufficient adjustment for relevant confounders, particularly dietary reporting accuracy, sweetened beverage intake and pubertal development. Despite limitations, available data suggest a neutral effect of dairy intake on adiposity during early and middle childhood and a modestly protective effect in adolescence.