When the cold gets under your skin: Evidence for brown adipose tissue activity in Samoan adults

Abstract

ObjectivesBrown adipose tissue (BAT) is a heat‐producing organ aiding nonshivering thermogenesis (NST) during cold stress. Due to its potential cold‐adaptive role BAT has been predominantly studied in cold and temperate climate populations, but not among warm‐climate adults. This work explores if BAT activity can be inferred in Samoans.Materials and MethodsWe inferred BAT activity by comparing metabolic rate and surface heat dissipation using indirect calorimetry and thermal imaging between room temperature and cold exposure among Samoans (N = 61, females: n = 38) from ‘Upolu Island, Samoa. BAT activity was inferred using ANOVA linear regression models with the variables measured at cold exposure as outcomes. T‐tests were used to compare changes in surface temperature between room temperature and cold exposure.ResultsMetabolic rate significantly increased after cooling. In both the supraclavicular area, a known BAT location, and the sternum, a non‐BAT location, temperatures decreased significantly upon cold exposure. Differences in supraclavicular temperatures between room temperature and cold were significantly smaller than differences in sternum temperatures between exposures. These results suggest that BAT thermogenesis occurred in known BAT‐locations and thus contributed to NST during cooling.ConclusionsThis study adds to our understanding of BAT activity across different populations and climates. Further study may illuminate whether the cold‐adaptive properties of BAT may have played a role in the successful expansion of populations across the globe, including warm‐climate groups.

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

“…Study setting and sample are described in‐depth elsewhere (Niclou et al, 2023). In brief, participants from ‘Upolu Island, Samoa were contacted from previous genetic studies of obesity conducted by members of this author team (Hawley et al, 2014; Hawley et al, 2020; LaMonica et al, 2022; Minster et al, 2016).…”

“…The present work explores the associations between respiratory quotient (RQ)—a measure inferring substrate metabolism, fasting glucose, and cholesterol levels with inferred BAT activity during cold exposure among adults in Samoa (McClave et al, 2003). The following investigation derives its understanding of evidence for significant BAT activity from previous work conducted among the same individuals who participated in the present study (see Niclou et al, 2023). By exploring the associations between inferred BAT activity and changes in metabolic health markers upon cold exposure, this work sheds light on the variation in effects of inferred BAT activity on metabolism and promotes discussion on how BAT may contribute to metabolic heath in Samoans.…”

“…While mostly inactive under thermoneutral or warm conditions, BAT is activated at mild cold exposure (15–19°C) and contributes to non‐shivering thermogenesis (NST) (Cannon & Nedergaard, 2004; Ouellet et al, 2012). This thermogenic activity has an appreciable effect on total energy expenditure and metabolic rate in humans, which may contribute to increased metabolic and cardiovascular health in individuals with measurable BAT activity (Becher et al, 2021; Niclou et al, 2023; Niclou & Ocobock, 2022; Ouellet et al, 2012; Wibmer et al, 2021). Despite the promising effects of BAT activation on health, relatively little work has been done on BAT activity and its potential association with metabolic health among populations with high rates of obesity or diabetes.…”