Brown Fat is Associated with Lower Prevalence of Cardiometabolic Diseases

by | Feb 8, 2021 | 2021, Cardiovascular Health, Diabetes, Obesity

Written by Joyce Smith, BS. Study results suggest that brown fat (BAT) reduces the risk of cardiometabolic diseases in overweight and obese individuals.

cardiovascular healthSince 2003, BAT or brown fat has been studied in both newborns and animals. It was only in 2009 and later when scientists discovered the presence of brown fat in some adults, typically around the supraclavicular (neck and shoulders) area 1. Small prospective studies that followed demonstrated how cold-activated brown fat in healthy humans is thermogenic and dissipates energy as heat, and that this increased energy expenditure increases glucose metabolism and burns fat tissue to produce free fatty acids 2,3. These studies were too small to address brown fat as an intervention for treating obesity and obesity-related metabolic and cardiovascular diseases, thus the following study was designed to evaluate whether brown fat might mitigate the negative effects of obesity.

In the following study 4, researchers reviewed 134,529 PET/CT (18 F-FDG positron emission tomography computed tomography) reports of 52,487 patients that were generated between June and March 2018. The scans, done at the Memorial Sloan Kettering Cancer Center, were done on patients as part of their cancer diagnosis and any detected brown fat was noted by radiologists. Thus the research team was provided with a large study cohort of 14,923 individuals (5,070 with reported brown fat and 9,853 without reported brown fat).

Analysis revealed the following:

  • Individuals with BAT had lower prevalence of cardiometabolic diseases, and the presence of BAT was independently correlated with significantly lower odds of type 2 diabetes (T2DM, P<0.0001), dyslipidemia (P=0.0029), coronary artery disease (CAD, P=0.0002), cerebrovascular disease (CVD, P=0.0317), congestive heart failure (CHF, P=0.0043), and hypertension (P=0.0014).
  • Brown fat was more prevalent in women than men (13.8% versus 4.9%); decreased with participant age and correlated inversely with ambient temperature and body mass index (BMI) (P< 0.0001) for all.
  • Brown fat was more prevalent in the cervical and supraclavicular areas (82 and 88 % respectively) compared to the paraspinal (58%), mediastinal (50%), axillary 31%) and abdominal (21%) areas.
  • The cohort without brown fat had a significantly stronger association between beta blockers, statin use and brown fat prevalence (P<0.0001 vs. P=0.0058) compared to the cohort with brown fat.
  • A higher prevalence of brown fat was associated with a higher number of breast cancers 5,6 but negatively associated with non-Hodgkin’s lymphoma and leukemias.
  • The beneficial effects of brown fat were more pronounced in individuals with higher body mass index (BMI) who were overweight or obese (T2DM and CVD increased with higher BMIs) suggesting that brown fat might play a role in mitigating the damaging effects of obesity.

The actual mechanisms by which BAT may contribute to better health are still under investigation; however, brown fat cells metabolize glucose for energy thus lowering glucose levels which are a major risk factor for T2DM. Researchers also suggest a potential endocrine and paracrine crosstalk with other organ systems which might explain the increased CAD risk in patients with no BAT. Further work exploring the role of BAT in systemic metabolism is warranted.

Source: Becher, Tobias, Srikanth Palanisamy, Daniel J. Kramer, Mahmoud Eljalby, Sarah J. Marx, Andreas G. Wibmer, Scott D. Butler et al. “Brown adipose tissue is associated with cardiometabolic health.” Nature Medicine (2021): 1-8.

© The Author(s), under exclusive licence to Springer Nature America, Inc. 2021

Click here to read the full text study.

Posted February 8, 2021.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

References:

  1. van Marken Lichtenbelt WD, Vanhommerig JW, Smulders NM, et al. Cold-activated brown adipose tissue in healthy men. The New England journal of medicine. 2009;360(15):1500-1508.
  2. Yoneshiro T, Aita S, Matsushita M, et al. Brown adipose tissue, whole-body energy expenditure, and thermogenesis in healthy adult men. Obesity (Silver Spring, Md). 2011;19(1):13-16.
  3. Orava J, Nuutila P, Lidell ME, et al. Different metabolic responses of human brown adipose tissue to activation by cold and insulin. Cell Metab. 2011;14(2):272-279.
  4. Becher T, Palanisamy S, Kramer DJ, et al. Brown adipose tissue is associated with cardiometabolic health. Nat Med. 2021;27(1):58-65.
  5. Steinberg JD, Vogel W, Vegt E. Factors influencing brown fat activation in FDG PET/CT: a retrospective analysis of 15,000+ cases. The British journal of radiology. 2017;90(1075):20170093.
  6. Cao Q, Hersl J, La H, et al. A pilot study of FDG PET/CT detects a link between brown adipose tissue and breast cancer. BMC Cancer. 2014;14:126.