Infrared thermography unveiled the variation of brown adipose tissue thermogenesis among East Asian adults

The thermogenesis of brown adipose tissue (BAT) is interesting because the contribution to human adaptation to cold and obesity resistance has been suggested. ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) is a common method for measuring BAT activity; however, it has been studied in few large cohorts due to concerns about safety and cost. Studies using alternative methods make it challenging to directly compare BAT activity among studies and interpret those results because the procedure is various. We measured the supraclavicular BAT thermogenesis of 122 healthy Japanese and Chinese adults under mild cold stress using standardized infrared thermography (IRT) and examined the effects of various factors on BAT variation. BAT thermogenesis was significantly higher in females than in males (p < 0.001) and significantly higher in Chinese than in Japanese individuals (p < 0.05). Among the 27 participants enrolled in both summer and winter experiments, BAT thermogenesis increased during winter (p < 0.05) only in Japanese participants. Additionally, individuals born at higher latitudes exhibited greater BAT thermogenesis (p < 0.05), suggesting the involvement of genetic background or cold exposure in early life stages. We obtained interesting anthropological and physiological findings with the use of non-invasive IRT.