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 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-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 one percent unit increase in %BAT was associated with lower body mass index, difference (95%CI), -0.08 (-0.10, -0.06) kg/m 2 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.