A study published by researchers at Rockefeller University in the journal Nature Medicine recently revealed that, according to data sourced from over 50,000 clinical trial participants, having a greater proportion of brown fat is associated with a reduced risk of multiple chronic diseases tied to metabolism.
In a large-scale review, clinical trial participants who did have detectable brown fat enjoyed a reduced risk of cardiac and metabolic conditions ranging from type 2 diabetes to coronary artery disease, which is the leading cause of death in the United States.
The study, by far the largest of its kind in humans, confirms and expands the health benefits of brown fat suggested by smaller clinical studies. “For the first time, it reveals a link to lower risk of certain conditions,” Paul Cohen, MD, assistant professor and senior attending physician at The Rockefeller University Hospital, said. “These findings make us more confident about the potential of targeting brown fat for therapeutic benefit.”
A Novel Approach
According to the authors of the study, brown adipose tissue has previously been studied for decades in newborns and animals, but it was not until 2009 that scientists began theorizing about instances in which it appeared in adults. Typically, adults can have brown fat around the neck and shoulders, and since then, much work has been done in an attempt to understand what health benefits the presence of brown fat can have, and what dietary patterns might be associated with its presence in adults.
The tissue only shows up on PET scans, a special type of medical imaging. “These scans are expensive, but more importantly, they use radiation,” Tobias Becher, the study’s first author and formerly a clinical scholar in Cohen’s lab, said. “We don’t want to subject many healthy people to that.”
However, many cancer patients undergo PET scans each year for standard evaluations, and radiologists take note of brown fat to make sure it is not mistaken for a tumor, the authors said. “We realized this could be a valuable resource to get us started with looking at brown fat at a population scale,” Becher said.
After reviewing 130,000 PET scans from more than 52,000 patients, researchers observed the presence of brown fat in 10% of clinical trial participants. The figure might be an underestimate, however, as the participants were instructed to avoid cold exposure, exercise, and caffeine, all three of which are thought to increase brown fat activity.
Several common and chronic diseases were less prevalent among people with detectable brown fat. Only 4.6% had type 2 diabetes, compared with 9.5% of people who did not have detectable brown fat. 18.9% of people with brown fat had abnormal cholesterol, compared to 22.2% in those without brown fat.
Significant reductions achieved in those with brown fat were also observed in hypertension, congestive heart failure, and coronary artery disease, and these three links were not observed in previous studies.
Brown fat, even among obese people, appeared to mitigate the risk of obesity-related diseases. Among obese people with brown fat, the prevalence of the aforementioned medical conditions mirrored that of non-obese people.
How Does it Work?
While brown fat’s ability to burn energy more efficiently than white fat is apparent, the authors of the study noted a number of other potential biological mechanisms which the protective effect may be attributed to. One example is that brown fat tissue metabolizes glucose to burn calories, which may lower blood glucose levels, attenuating type 2 diabetes risk. Other links, such as those to hypertension, remain a mystery.
The authors of the study intend to continue researching the role that brown fat plays in overall health and disease risk management, as well as potential pharmacological therapies which could stimulate brown fat activity and treat obesity and its related conditions.