Brown Fat Likely Key To Filtering Out Certain Amino Acids Linked To Diabetes And Obesity

Scientists from Rutgers and other institutes have uncovered how brown fat, or brown adipose tissue, is useful in fighting against obesity and diabetes.

There are two types of fat. White, or yellow fat, is used for energy storage. When fuel is needed, it is released from white fat.

Brown fat, also known as “good” fat, is used to process food and churn out body heat. This is the type of fat that can be found in high amounts in newborn humans and hibernating animals.

A few grams of this fat can be found in our neck, collarbone, kidneys and spinal cord. In cold temperatures, brown fat gets activated and takes sugar and fat out of the blood to generate heat in the body.

The study, published in the journal Nature, also found that brown fat possibly filters the blood to remove branched-chain amino acids (BCAAs). BCAAs are a group of essential amino acids that comprises of leucine, isoleucine and valine. These amino acids are not naturally produced in the body but are commonly taken through supplements to boost muscle development and raise exercise performance.

At regular blood levels, BCAAs are important for good health. On the other hand, they are associated with diabetes when in surplus. People lacking brown fat are less efficient at clearing BCAAs from the blood, which can contribute to obesity and diabetes.

The study also solved a 20-plus year riddle about brown fat: how BCAAs move into the mitochondria that generate energy and heat in cells. The scientists discovered that a unique protein, known as SLC25A44, regulates the speed at which brown fat utilises the amino acids in the blood to produce energy and heat.

"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," said co-author Labros Sidossis, a Distinguished Professor who chairs the Department of Kinesiology and Health in the School of Arts and Sciences at Rutgers University-New Brunswick. He is also a professor in the Department of Medicine at Rutgers Robert Wood Johnson Medical School in Rutgers Biomedical and Health Sciences.

The next step researchers need to take is to establish if uptake of BCAAs by brown fat can be manipulated by environmental elements, such as exposure to slightly cold temperatures (65 degrees Fahrenheit), eating spicy foods, or by drugs. This has the potential to improve blood sugar levels that are linked to diabetes and obesity, Sidossis said.