Brown adipose tissue, energy expenditure, and biomarkers of cardio‐metabolic health among the Yakut (Sakha) of northeastern Siberia

Abstract

Objectives: This study provides the first investigation of non-shivering thermogenesis (NST) and brown adipose tissue (BAT) activity among an indigenous circumpolar population, the Yakut of northeastern Siberia. The study also examines the health significance of BAT activity in this population by testing the relationships between BAT thermogenesis and biomarkers of cardio-metabolic disease risk, such as percent body fat and blood glucose and cholesterol levels. Methods: Data were collected in the Sakha Republic (Yakutia) for 31 men and 43 women. Change in energy expenditure and BAT thermogenesis were quantified after a 30-minute mild cooling condition. Anthropometric dimensions, blood glucose, and lipid levels were also collected. Results: On average, the skin temperature of the supraclavicular area was constant after cooling while the skin temperature of a point on the sternum dropped significantly (P < .001), thus suggesting the presence of active supraclavicular BAT among Yakut adults. Participants with evidence of greater BAT thermogenesis exhibited a larger percent change in energy expenditure (% ΔEE) and an increase in respiratory quotient (RQ) after cooling (P ≤ .05). While there was no relationship between BAT activity and blood lipid levels, BAT thermogenesis was positively associated with blood glucose levels (P < .01). Conclusions: Yakut adults exhibit evidence of active BAT deposits. Given that there is a significant relationship between BAT activity and % ΔEE, it is possible that BAT plays a role in NST among Yakut adults. While the relationship between BAT and body composition is inconclusive, participants with greater BAT seemed to preferentially utilize glucose during cold stress exposure.

Field and laboratory methods for quantifying brown adipose tissue thermogenesis

“…An alternative option is to use a semi‐individualized protocol that also aims to maximize NST and minimize shivering. Levy et al () used a 30‐minute semi‐individualized cooling protocol to examine the relationship between BAT thermogenesis and cold‐induced changes in energy expenditure among Yakut adults, a population indigenous to northeastern Siberia. During the cooling condition, cold water (mean temperature: 10.3°C ± 2.9°C) was pumped through a water‐perfused suit (Med‐Eng) so that the internal temperature of the suit was maintained at ~15°C.…”

“…Previous work indicates that indigenous circumpolar populations adapt to chronic cold stress through persistent elevations in basal metabolic rate (BMR) and seasonal shifts in thyroid hormone dynamics (Froehle, ; Levy et al, ; Rode & Shephard, ; Snodgrass, Leonard, Tarskaia, Alekseev, & Krivoshapkin, ). Recent research suggests that populations living in high‐latitude regions may also adapt to cold exposure by increasing their non‐shivering thermogenesis (NST) (see Table for definitions of key terms) via the metabolic and endocrine action of brown adipose tissue (BAT) (Levy et al, ).…”

“…When UCP1 is integrated into the mitochondrial membrane, it uncouples oxidative phosphorylation from ATP production, resulting in inefficient metabolism and greater heat production (Lowell & Spiegelman, ). This process is referred to as BAT thermogenesis (Levy, ; Levy et al, ). Adult BAT is found primarily in the neck and above the clavicles, and occasionally around the spine, heart, kidneys, pancreas, liver, spleen, and scattered within white fat deposits of the greater omentum and mesocolon (Sacks & Symonds, ).…”

“…Adults with greater BAT thermogenesis exhibit a larger increase in whole‐body energy expenditure during cold exposure, suggesting a mechanistic link between BAT metabolism and NST (Chen et al, ; Hanssen et al, ; Levy et al, ; Otto Muzik, Mangner, Leonard, Kumar, & Granneman, ; van der Lans et al, ; van der Lans et al, ; van van Marken Lichtenbelt et al, ; Vosselman et al, ). Among the Yakut, a population that is indigenous to northeastern Siberia, adults with greater BAT thermogenesis expend more energy during acute cold stress (Levy et al, ). Additionally, populations living in temperate zones increase their BAT metabolism in response to repeated cold exposure and exhibit seasonal changes in BAT mass (Nirengi et al, ; van der Lans et al, ).…”

Biological Anthropology in 2018: Grounded in Theory, Questioning Contexts, Embracing Innovation

“…), and that supraclavicular brown adipose tissue in Yakut adults (Siberia) may play a role in nonshivering thermogenesis and, therefore, cold adaptation in this population (Levy et al. ).…”