Indication of mixed glucose and fatty acid use by inferred brown adipose tissue activity in Samoans.

Objectives: Despite the growing rates of global obesity and the known positive associations between brown adipose tissue (BAT) and cardiovascular health, little is known about the metabolic effects of BAT activity in Samoans, a population at high risk of obesity and type II diabetes. Here we assessed the potential effects of inferred BAT activity on metabolic health markers in Samoan adults exposed to mild cold.

Methods: Using point-of-care finger prick technology we measured fasting glucose, total cholesterol, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) levels before and after 30 min of cold exposure among 61 individuals (38 females, 23 males, ages 31-54) from 'Upolu Island, Samoa. Respiratory quotient was measured by indirect calorimetry to determine substrate metabolism at room temperature and cold exposure.

Results: Fasting glucose levels decreased significantly (p < .001) after cold exposure while neither total cholesterol (p = .88), HDL (p = .312), nor LDL (p = .089) changed. Respiratory quotient decreased significantly (p = .009) between exposures, suggesting an increased preference for lipid metabolism as a response to cold.

Conclusions: The observed effects of inferred BAT activity on biomarkers suggest BAT activity utilizes both glucose and lipid-derived fatty acids as fuel for thermogenesis. Our work provides evidence for the beneficial metabolic effects of BAT and emphasizes the need for the population-specific development of metabolic treatments involving BAT to ensure the successful and equitable minimization of extreme consequences of obesity and metabolic health.