Brown fat, which is found around the neck and shoulders, was once thought only to be beneficial to newborns, but has more recently been thought to have beneficial health effects in humans. However, it has been challenging to study since it is so deeply buried.
In mouse models, brown fat is known to be thermogenic, significantly improving glucose and lipid homeostasis, but in humans its role in metabolism and cardiovascular disease was still unclear. The prevalence of brown fat is difficult to measure in humans, since the only noninvasive way to detect it is with expensive PET scans. However, radiologists have to distinguish brown fat from tumours in PET scans, and this provided a valuable resource to establish the prevalence of brown fat in the population. The researchers used 134 529 PET scans of 52 487 patients.
Brown fat was found in some 10% of the population, which may be an underestimate since individuals undergoing the scans were told to avoid cold, exercise and caffeine, which are all known to increase the activity of brown fat.
“For the first time, it reveals a link to lower risk of certain conditions,” said Paul Cohen, Assistant Professor at The Rockefeller University Hospital. “These findings make us more confident about the potential of targeting brown fat for therapeutic benefit.”
Despite this new evidence, exactly how brown fat contributes to health is still unclear, although there are some clues. Brown fat uses glucose to generate energy, and this may help lower blood glucose levels. The role hat brown fat plays in hypertension, which is tightly connected to the hormonal system, is less clear.”We are considering the possibility that brown fat tissue does more than consume glucose and burn calories, and perhaps actually participates in hormonal signaling to other organs,” Cohen says.
The researchers plan to investigate the biology of brown fat, such as by looking for genetic variations to explain why some have it and others do not, which may lead to pharmacological treatments.
“The natural question that everybody has is, ‘What can I do to get more brown fat?'” Cohen said. “We don’t have a good answer to that yet, but it will be an exciting space for scientists to explore in the upcoming years.”
Source: Medical Xpress
Journal information: Becher, T., Palanisamy, S., Kramer, D.J. et al. Brown adipose tissue is associated with cardiometabolic health. Nat Med (2021). doi.org/10.1038/s41591-020-1126-7
