Brown fat could help get rid of harmful compounds linked to conditions such as obesity and diabetes, scientists believe.
The research, published in the journal Nature, shines a light both on brown fat as well as compounds called branched-chain amino acids (BCAAs), which are among the nine “essential” amino acids which human proteins are made up of. BCAAs—valine, leucine and isoleucine—mainly come from meat, fish, dairy products and eggs, and are also found in some fitness supplements. High levels of BCAAs in the body have been linked to obesity, insulin resistance and type 2 diabetes in both humans and rodents.
When exposed to low temperatures, brown fat cells help turn energy stored in the body into heat. Sitting around the kidneys and adrenal glands, and to a lesser extent the blood vessels of the neck and the cavities between organs, our brown fat levels are the highest in the womb, and gradually drop in our first weeks of life.
The tissue is thought to play a role in how the body responds to heat and the control of body weight. For a while, researchers have been considering whether brown fat could be stimulated to burn more energy as a means to combat obesity.
To investigate the relationship between brown fat and BCAAs, the researchers studied 33 men. The participants were aged 23 on average. Tests revealed whether they had high or low levels of brown fat. The team exposed the men to temperatures of 27C (80.6F) and a cool 19C (66.2) for two hours. Next, they analyzed the levels of BCAAs in their blood.
The team discovered that men who had high levels of brown fat saw BCAA levels drop at the end of the tests. However, those with low levels of brown fat didn’t see a change in their BCAA levels.
The researchers also concluded that a specific protein called SLC25A44 is in charge of how quickly brown fat processes BCAAs from the blood to create heat.
Co-author Labros S. Sidossis, professor in the Department of Medicine at Rutgers Robert Wood Johnson Medical School, commented in a statement: “Our study explains the paradox that BCAA supplements can potentially benefit those with active brown fat, such as healthy people, but can be detrimental to others, including the elderly, obese and people with diabetes.”