Effect of habitual cold exposure on brown adipose tissue activity in Arctic adults: a systematic review.

Brown adipose tissue (BAT) is crucial for non-shivering thermogenesis, a key adaptation for humans in Arctic environments. The discovery of BAT presence in human adults has ignited curiosity due to its potential role in combating obesity, type II diabetes and cardiovascular diseases. Following PRISMA guidelines and preregistration (PROSPERO CRD42023444511) this systematic review aims to describe the evidence of BAT activity among adults living in the Arctic with habitual cold exposure. Systematic searches were conducted in PubMed, Embase, and Scopus as of November 2024. In addition, trial registration searches, manual screening of reference lists, and requests to experts were performed. No restrictions were made regarding study selection. Each study was assessed using the NIH Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Of 429 studies screened, 21 full texts were included for eligibility assessment, and eight studies qualified for inclusion. Due to the heterogeneity of the included studies, a meta-analysis was not pursued. Results indicate high BAT activity in Arctic populations, as supported by increased supraclavicular skin temperatures after cold exposure, thyroid hormone dynamics, and genetic markers linked to BAT. Findings highlight BAT's role in cold adaptation among adults residing in Arctic regions, though methodological limitations remain, necessitating further research.