A large study in over 52,000 people suggests that brown fat may help protect against many chronic diseases such as type 2 diabetes and hypertension. Details of this work are published in the journal Nature Medicine.
We have more than one type of fat in our body. The main type of fat cells is called white adipose tissue , named for its milky yellow color. The other is called brown adipose tissue , which is actually orange to reddish. Although brown fat has long been studied in newborns and animals, it was only recently that we discovered that it can also be found in some adults, usually around the neck and shoulders . From then on, researchers set out to study these fat cells.
Then we realized that brown fat does not behave the same way as white fat, but more like muscle. While the former stores energy and is associated with weight gain, brown fat is indeed thermogenic . In other words, it increases the heat in the body and burns the energy of white fat. However, that's about all we know so far.
The fact is that studying brown fat is a complicated business since these tissues only show up on PET scans, a special type of medical imaging. “These scans are expensive, but more importantly, they use radiation “, Details Tobias Becher, first author of the study. "We don't want to subject many healthy people to this “.
The researchers here offered an alternative. Not far from their lab in New York City is the Memorial Sloan-Kettering Cancer Center, a cancer treatment and research center visited by thousands of patients each year to undergo CT scans. Tobias Becher was aware that radiologists at this facility pay close attention to the brown fat visible on their scans to ensure it is not mistaken for a tumour .
"Also, we realized this could be a valuable resource for us to start looking at brown fat at the population level “, continues the researcher.
Using this "data bank", researchers examined 130,000 PET scans from over 52,000 patients , isolating the presence of brown fat in approximately 10% of individuals . They then pointed out that several common and chronic diseases were less frequent in these same people. For example, only 4.6% of them had type 2 diabetes, compared to 9.5% for the others. Similarly, 18.9% had developed abnormal cholesterol compared to 22.2% in those whose brown fat was undetectable.
Finally, those who had more brown fat had a lower risk of developing hypertension, congestive heart failure or coronary heart disease.
Another interesting point, it seems that brown fat reduces the negative health effects of obesity . The researchers found that among obese people who had brown fat, the prevalence of heart and metabolic disease was similar to that of non-obese people. “It looked like they were protected from the harmful effects of white fat “, emphasizes Tobias Becher.
This study thus extends the health benefits of brown fat. "For the first time, it reveals a link with a lower risk of certain diseases “, emphasizes Paul Cohen, of Rockefeller University Hospital. “These results make us more confident about the potential of targeting brown fat for therapeutic benefit “.
At this time, the mechanisms by which brown fat may contribute to better health are still unclear. According to the authors, it is possible that brown fat cells consume glucose to burn calories, lowering blood sugar levels in the process , which is a major risk factor for the development of diabetes. However, this process cannot explain everything. "We envision the possibility that brown adipose tissue does more than just consume glucose and burn calories “, notes the researcher. Further work will be needed here to determine this.
The authors also plan to focus on genetic variants capable of explaining why some people have more brown fatty tissue than others and aim to answer the famous question that everyone is now asking, "What can I do to get more brown fat? “.
