Brown Adipose Tissue, Adiposity, and Metabolic Profile in Preschool Children.

CONTEXT: An inverse relationship between brown adipose tissue (BAT) and obesity has previously been reported in older children and adults but is unknown in young children. OBJECTIVE: We investigated the influence of BAT in thermoneutral condition on adiposity and metabolic profile in Asian preschool children. DESIGN, SETTING, AND PARTICIPANTS: A total of 198 children aged 4.5 years from a prospective birth cohort study, Growing Up in Singapore Towards Healthy Outcomes (GUSTO) were successfully studied with water-fat magnetic resonance imaging of the supraclavicular and axillary fat depot (FDSA). Regions within FDSA with fat-signal-fraction between 20% and 80% were considered BAT, and percentage BAT (%BAT; 100*BAT volume/ FDSA volume) was calculated. MAIN OUTCOME MEASURES: Abdominal adipose tissue compartment volumes, ectopic fat in the soleus muscle and liver, fatty liver index, metabolic syndrome scores, and markers of insulin sensitivity. RESULTS: A 1% unit increase in %BAT was associated with lower body mass index, difference (95% CI), -0.08 (-0.10, -0.06) kg/m2 and smaller abdominal adipose tissue compartment volumes. Ethnicity and sex modified these associations. In addition, each unit increase in %BAT was associated with lower ectopic fat at 4.5 years in the liver, -0.008% (-0.013%, -0.003%); soleus muscle, -0.003% (-0.006%, -0.001%) of water content and lower fatty liver index at 6 years. CONCLUSIONS: Higher %BAT is associated with a more favorable metabolic profile. BAT may thus play a role in the pathophysiology of obesity and related metabolic disorders. The observed ethnic and sex differences imply that the protective effect of BAT may vary among different groups.