Large Study Reveals Prevalence, Health Benefits of Brown Fat
Posted on by Dr. Francis Collins
It’s pretty easy to spot differences between the two people on these positron emission tomography (PET) scans. In the scan of the male individual on the left, you see lots of small, dark spots around the neck and shoulders. But you can’t see any on the female on the right. What’s the explanation? Is this a sex difference? No! Brown fat!
This energy-burning type of fat happens to show up as small, dark spots in the neck and shoulder area on PET scan studies. So, as these scans reveal, the individual on the left possesses an abundance of brown fat, while the person on the right has essentially none. This wide range of difference in abundance is true for both men and women.
Researchers’ interest in brown fat began to heat up (sorry about that!) more than a decade ago when it was discovered that certain adults have persistently high levels of brown fat. It’s long been known that babies have brown fat, but it had been thought this fat generally vanished as children grew up. It turns out that adults who hold onto their brown fat are less likely to be overweight than adults who do not. That’s because brown fat actually burns extra calories, instead of storing it in the way the more familiar white fat does.
But are people with more brown fat actually any healthier? After studying about 130,000 PET scans from more than 52,000 people, researchers led by Paul Cohen, The Rockefeller University Hospital, New York, NY, say that the answer is “yes” in certain key areas. In a recent study in the journal Nature Medicine, they found that people with detectable brown fat had a lower incidence of many cardiovascular and metabolic conditions, including type 2 diabetes, congestive heart failure, and high blood pressure.
Studies to explore the health benefits of brown fat have been challenging to do. That’s because brown fat only shows up on PET scans, which measure how much glucose various tissues consume, an indication of their metabolic activity. What’s more, PET scans are quite costly and involve radiation exposure. So, researchers have been reluctant to ask healthy people to undergo a PET scan just to look at brown fat. But a solution occurred to the study’s first author Tobias Becher, who was aware that thousands of patients at nearby Memorial Sloan Kettering Cancer Center were undergoing PET scans each year as part of routine evaluation and care. In fact, cancer doctors often make note of brown fat on PET scans, if only to make sure it’s not mistaken for cancer.
So, the Cohen lab teamed up with Memorial Sloan Kettering Cancer Center radiologists Heiko Schöder and Andreas G. Wibmer to review many thousands of PET scans for the presence of brown fat. And they found it in about one of 10 people.
Next, they looked for health differences between the 10 percent of people with brown fat and the 90 percent who lack it. The differences turned out be striking. Type 2 diabetes was about half as prevalent in folks with detectable brown fat compared to those without. Individuals with brown fat also were less likely to have high cholesterol, high blood pressure, congestive heart failure, and coronary artery disease.
The findings suggest that brown fat may even help to offset the negative health effects of obesity. The researchers found that obese people with brown fat had a health profile that otherwise appeared more similar to individuals who weren’t obese. In fact, the benefits of brown fat were more pronounced in individuals who were overweight or obese than they were in people of normal weight.
Still, the researchers note that people with cancer might tend to show differences in brown fat compared to healthy adults. There’s some evidence also that prevalence may vary across cancer types and stages. The researchers took those variables into account in their studies. It’s also known that women are more likely to have brown fat than men and that the amount of brown fat tends to decline with age. What’s not yet well understood is whether differences in brown fat exist among people of different racial and ethnic backgrounds, and whether specific genetic factors are involved.
So, plenty of questions remain! Researchers not only want to figure out why some adults have so much more brown fat than others, they want to explore whether brown fat produces hormones that may add to its calorie-burning benefits. The hope is that these and other discoveries could eventually lead to new strategies for treating obesity, diabetes, and other metabolic conditions.
Reference:
[1] Brown adipose tissue is associated with cardiometabolic health. Becher T, Palanisamy S, Kramer DJ, Eljalby M, Marx SJ, Wibmer AG, Butler SD, Jiang CS, Vaughan R, Schöder H, Mark A, Cohen P. Nat Med. 2021 Jan;27(1):58-65.
Links:
Paul Cohen (The Rockefeller University, New York, NY)
Heiko Schöder (Memorial Sloan Kettering Cancer Center, NY)
Andreas Wibmer (Memorial Sloan Kettering Cancer Center, NY)
NIH Support: National Center for Advancing Translational Sciences
Is there a bottom line way to increase this miracle fat? I sort of remember something about cold increasing it – wear an ice pack while exercising? Is that what all those cool-sculpting spas are doing? I don’t have time to research this but would love to know since I keep getting more of that wrong kind of fat…
“Correlation is not causation” is the literally classic “cum hoc, ergo propter hoc” fallacy.
I KNOW you know this – but still need to be careful how you express findings in cross-sectional studies, particularly for lay readers. Use of the word ‘benefits’ implies something your study did not show.
Even IF chance and known factors are ‘sufficiently’ excluded by statistical analysis as explanations for the correlation, you still have 3 remaining classes of possibility, not one:
1. A may be causing B (article suggests to average readers there are protective effects of brown fat, but this is NOT a valid conclusion from this study, even though it is “possible”. But it was already “possible” BEFORE the study, so this alone is not news.)
2. B may be causing A (T2DM may erase / cause metabolism of brown fat previously/normally present, for example)
3. C may cause both A & B (over a billion possible ‘C’ etiologic factors besides CA, age, gender, and usual suspects one did ‘control for’. (Also as you know, so this is mentioned for other readers: One can only ‘exclude by analysis’ those possible factors a) that one suspects, b) that one consistently notes in the study record, c) which are ‘random’ elements of study inclusion, and d) which one has sufficient numbers of, to reach a statistically confident conclusion.)
4. And still ‘Chance’ remains as a possible though now less likely explanation, too: up to one in 20 statistically significant (p<.05) or one in 100 (p<.01) and well-designed and performed findings of correlation, are, none-the-less, mere chance effects. Thousands of well-designed, peer-reviewed, published, one of kind studies, do report findings that are untrue every year.
And these untruths & pretruths are reported as headliners of wonderful new scientific truths.
No wonder there is an anti-science backlash.
Notwithstanding the size of one’s p, our readers need to know we know that approximating meaningful scientific ‘truth’ is a longer and more complicated road than getting enough money for a sufficiently 'powerful' sample size, or cleverly finding an existing ‘experiment of nature’ that may by-pass need for a designed study.
And they need to know we know that correlation is not causation, EVERY time we report an observational study. If scientists can forget this, lay people can never be expected to know it. In the long run, going for the headline gets attention at the expense of credibility. Funding is not meaning or truth. Air-time may 'work' for the attention span, knowledge, and IQ of political reality, but I think you will find, not for science.
In what kind of food or diet habit you’ll have brown fat to eat on a dayly basis ?
Might be interesting to compare the gut microbiome of these individuals.
Is focusing about this somatic body of 32 faecal matters is the most important thing? At any rate very few live live beyond 85 to 90 years, and last few years aged, unable to look after self, in care homes etc. Then this body is dumped in the earth and that is it.
But this body is not there to only look at what proteins, fats or vitamins to be put inside, but for a much greater and Utopian purpose. It is there to serve others, but more so to serve self, how? It is there to help in the development of Mindfulness and Wisdom. But sadly though so few are aware of this.
Thanks for explaining this lessor known fact of brown fat. Obesity, overweight has become a very big issue now a days. People start diets, heavy exercises and harm their body as well. It was good to know about the various health related benefits of brown fat.