By Abby Phillip
By now, you may have heard about brown adipose tissue, or "brown fat." It is a type of fat, most likely present in all humans, that is a super calorie burner.
In recent years, a renewed interest in brown fat has revealed some promising attributes. Not only does brown fat play a role in warming up the body in cold temperatures, but by doing that, it is also an extraordinarily efficient calorie burner. And while some people may have more of this fat than others, there are ways of increasing the amount of brown fat in your body.
A new study has unveiled a piece of the puzzle in the emerging research into this remarkable tissue. Brown fat, it turns out, acts as a "super vacuum" to suck up excess glucose (sugar) in the blood by producing large amounts of a substance that transports glucose into the brown fat cells, where it can be burned to produce heat -- a process called thermogenesis.
"If you can start the tissue to burn and produce heat, then you can actually in a way take away excess glucose in the blood," said Tore Bengtsson, one of the study's authors and a professor of physiology at Stockholm University in Sweden. "Now we actually understand how this production of these glucose transporters work."
Brown fat cells do this at a more efficient rate than other mechanisms the body uses to absorb glucose in the blood. When activated, the brown fat cells produce 10 or more times the amount of glucose transporters than insulin, for example, according to Bengtsson.
For people with type 2 diabetes, whose bodies do not use insulin properly and as a result have elevated blood glucose levels, these findings could lead to new drugs that can activate brown cells and reduce blood glucose levels without insulin.
More than 29 million Americans live with type 2 diabetes, according to the American Diabetes Association. And more than one-third of U.S. adults are obese, according to the Centers for Disease Control and Prevention; obesity can lead to the development of type 2 diabetes.
"The implication of this is normally when you have type 2 diabetes you have to inject insulin to reduce your blood sugar levels," Bengtsson said. "However you could make a medicine which is not based on insulin signalling. It's a completely new pathway that can be targeted for taking up glucose in the blood."
The study, published in the Journal of Cell Biology on Monday, helps to connect the dots between years of findings suggesting that better understanding brown tissue can lead to new treatments for obesity and type 2 diabetes. The tissue, which is typically found around the neck and spinal cord, is more present in the body when you are young; people who are overweight or obese tend to have less of it.
Initially, beyond infants who need the heat-producing tissue to maximize survival in the first days and months of life, scientists didn't fully understand whether adult humans had and used brown tissue. But recent research has also found that the amount of brown tissue grows in cold weather or when people are exposed to cold environments. Conversely, it declines in warm environments.
The findings support what scientists believe are the evolutionary origins of the tissue. In mammals and in humans, it helps regulate body temperature by converting glucose and free fatty acids in the blood into heat that the body might need to survive in colder temperatures.
"Brown fat has been investigated for a very long time in small mammals," noted Bengtsson. "Five or six years ago, we actually understood that we had brown fat in humans and the brown fat is working in humans -- not only in infant humans but in adults."
Bengtsson said that he is working on the next step in the research -- looking for specific ways of activating the cells, which will be crucial for the development of new drugs.