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Nicotinamide Riboside Enhances In Vitro Beta-adrenergic Brown Adipose Tissue Activity in Humans.
Nascimento, EBM, Moonen, MPB, Remie, CME, Gariani, K, Jörgensen, JA, Schaart, G, Hoeks, J, Auwerx, J, van Marken Lichtenbelt, WD, Schrauwen, P
The Journal of clinical endocrinology and metabolism. 2021;106(5):1437-1447
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Plain language summary
Brown fat is a type of fat that burns energy to regulate the body’s temperature in cold conditions. A high level of activity in the brown fat has been associated with healthy whole-body metabolism. Several supplements have been investigated for their potential to activate brown fat, however many of these have limiting side effects. Nicotinamide riboside (NR), also known as vitamin B3, is a supplement which can boost energy burning pathways within the body. This randomised control trial was part of a larger trial including a study on human brown fat cells and aimed to determine whether NR supplementation in overweight and obese individuals may act on the activity of brown tissue. The results showed that 6 weeks of NR supplementation had no effect on brown tissue activity or energy expenditure. It was concluded that NR supplementation for 6 weeks in individuals with obesity had no effect on brown fat tissue for reasons unknown, as the cellular study showed an increase in activity. This study could be used by healthcare professionals to better understand the role of brown fat in metabolism.
Abstract
CONTEXT Elevating nicotinamide adenine dinucleotide (NAD+) levels systemically improves metabolic health, which can be accomplished via nicotinamide riboside (NR). Previously, it was demonstrated that NR supplementation in high-fat-diet (HFD)-fed mice decreased weight gain, normalized glucose metabolism, and enhanced cold tolerance. OBJECTIVE Because brown adipose tissue (BAT) is a major source of thermogenesis, we hypothesize that NR stimulates BAT in mice and humans. DESIGN AND INTERVENTION HFD-fed C56BL/6J mice were supplemented with 400 mg/kg/day NR for 4 weeks and subsequently exposed to cold. In vitro primary adipocytes derived from human BAT biopsies were pretreated with 50 µM or 500 µM NR before measuring mitochondrial uncoupling. Human volunteers (45-65 years; body mass index, 27-35 kg/m2) were supplemented with 1000 mg/day NR for 6 weeks to determine whether BAT activity increased, as measured by [18F]FDG uptake via positron emission tomography-computed tomography (randomized, double blinded, placebo-controlled, crossover study with NR supplementation). RESULTS NR supplementation in HFD-fed mice decreased adipocyte cell size in BAT. Cold exposure further decreased adipocyte cell size on top of that achieved by NR alone independent of ex vivo lipolysis. In adipocytes derived from human BAT, NR enhanced in vitro norepinephrine-stimulated mitochondrial uncoupling. However, NR supplementation in human volunteers did not alter BAT activity or cold-induced thermogenesis. CONCLUSIONS NR stimulates in vitro human BAT but not in vivo BAT in humans. Our research demonstrates the need for further translational research to better understand the differences in NAD+ metabolism in mouse and human.
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Brown Adipose Crosstalk in Tissue Plasticity and Human Metabolism.
Scheele, C, Wolfrum, C
Endocrine reviews. 2020;41(1)
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Free full text
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Plain language summary
Brown adipose tissue (BAT) is an important contributor to the regulation of metabolism via cellular communication with organs such as liver, muscle, gut and central nervous system. BAT is important for heat generation and is at high levels in human infants. Levels of activation of BAT decline as we age and it has been shown that the amount of BAT is smaller and its activity reduced in those with obesity and type 2 diabetes. To date, there is no answer to efficiently restore functional BAT in aging and obese subjects. This review looks at experiments done on the factors secreted from active BAT (batokines). The review aims to provide a structure for the processes and cell types involved in BAT and the recent findings of BAT whole-body communication are discussed. Altogether, these findings demonstrate that BAT has an adaptive capacity. Studying batokines, offers an alternative approach to identify novel drug targets for metabolic regulation.
Abstract
Infants rely on brown adipose tissue (BAT) as a primary source of thermogenesis. In some adult humans, residuals of brown adipose tissue are adjacent to the central nervous system and acute activation increases metabolic rate. Brown adipose tissue (BAT) recruitment occurs during cold acclimation and includes secretion of factors, known as batokines, which target several different cell types within BAT, and promote adipogenesis, angiogenesis, immune cell interactions, and neurite outgrowth. All these processes seem to act in concert to promote an adapted BAT. Recent studies have also provided exciting data on whole body metabolic regulation with a broad spectrum of mechanisms involving BAT crosstalk with liver, skeletal muscle, and gut as well as the central nervous system. These widespread interactions might reflect the property of BAT of switching between an active thermogenic state where energy is highly consumed and drained from the circulation, and the passive thermoneutral state, where energy consumption is turned off. (Endocrine Reviews 41: XXX - XXX, 2020).