A large new study has provided strong evidence that people with brown fat in their bodies are less likely to suffer from a range of health problems.
“For the first time, it reveals a link with a lower risk of certain conditions,” said one of the researchers, Rockefeller University Hospital physician Paul Cohen.
“These findings give us more confidence in the potential to target brown fat for therapeutic benefit.”
Brown fat or brown adipose tissue (BAT) is especially common in overwintering mammals and newborns. BAT helps mammals regulate their temperature – when we’re very cold, the large amounts of mitochondria in this type of adipose tissue burn energy and produce heat. In fact, the iron-rich mitochondria give brown fat its characteristic color.
It wasn’t until 2009 that scientists discovered that some adult people also have brown fat in their bodies, usually around the neck and shoulders.
There have been many mouse studies looking at the benefit of brown fat, but in humans the research has been more obscure until recently. Having brown fat appears to improve a person’s metabolism and may even help with weight loss (although the latter is probably not that easy).
“The natural question everyone has is, ‘What can I do to get more brown fat?’” Cohen says.
“We don’t have a good answer to that yet, but it will be an exciting space for scientists to explore in the coming years.”
Looking at a large data set of 52,487 participants who underwent PET / CT scans for cancer evaluation, the team found evidence of brown fat in just under 10 percent of cases (5,070 people).
The researchers think this is an underestimate because of the conditions the participants were in – they were told to avoid exposure to cold, exercise, and caffeine before the scans, all of which have been linked to brown fat activity.
About 4.6 percent of people with brown fat also had type 2 diabetes, compared to 9.5 percent in the ‘no brown fat’ group. A similar result was seen with abnormal cholesterol results – 18.9 percent of people with brown fat had abnormal cholesterol, compared with 22.2 percent of people who had no brown fat.
Hypertension, congestive heart failure and coronary heart disease also saw small positive differences in the brown fat versus no brown fat groups.
“These findings were supported by improved high-density blood glucose, triglycerides and lipoproteins,” the team writes in their new paper.
While the numbers here are exciting, there’s no evidence yet that brown fat makes you immune to any of these conditions – but there’s a link with reduced risk worth investigating further.
What was really interesting, however, is that brown fat was particularly protective in obese people. Those obese brown fat patients had a similar prevalence of these metabolic and heart conditions as non-obese people.
“They almost seem like they are protected from the harmful effects of white fat,” Cohen says.
“Taken together, our findings highlight a potential role for BAT in promoting cardiometabolic health,” the researchers note in their paper.
It’s important to note that the data the researchers worked with came from cancer evaluations at Memorial Sloan Kettering Cancer Center, meaning this is not a sample representative of the general population.
Nonetheless, the study has provided a fascinating new look at the role of brown fat in the human body, and will hopefully lead to even more discoveries in the future.
“We are considering the possibility that brown adipose tissue does more than just consume glucose and burn calories, and may even contribute to hormonal signaling to other organs,” Cohen says.
The research is published in Nature Medicine.