Scope: Brown and brite adipocytes within the mammalian adipose organ provide non-shivering thermogenesis and thus, have an exceptional capacity to dissipate chemical energy as heat. Polyunsaturated fatty acids of the n3-series, abundant in fish oil, have been repeatedly demonstrated to enhance the recruitment of thermogenic capacity in these cells, consequently affecting body adiposity and glucose tolerance. We scrutinized these effects in mice housed in a thermoneutral environment and in a human dietary intervention trial.

Methods and results: Mice were housed in a thermoneutral environment eliminating the superimposing effect of mild cold-exposure on thermogenic adipocyte recruitment. Dietary fish oil supplementation in two different inbred mouse strains neither affected body mass trajectory nor enhanced the recruitment of brown and brite adipocytes, both in the presence and absence of a β3 adrenoreceptor agonist imitating the effect of cold-exposure on adipocytes. In line with these findings, dietary fish oil supplementation of persons with overweight or obesity failed to recruit thermogenic adipocytes in subcutaneous adipose tissue.

Conclusion: Thus, our data question the hypothesized potential of n3-polyunsaturated fatty acids as modulators of adipocyte-based thermogenesis and energy balance regulation. This article is protected by copyright. All rights reserved.