The brown fat from the neck to the lower chest is hope in the fight against obesity and its negative effects. It produces energy and heat through metabolic changes. Its occurrence, however, depends on health, condition and age – in adults it is insular and the tissue is clearly thinner. Scientists are working on restoring it to the form in which it occurs in adolescents.
A team of scientists from Sahlgrenska Akadamin, department of Göteborgs Universitet, led by prof. Sven Enerbäck, dealt with the problem of metabolic changes causing obesity. In the course of the research, scientists discovered two types of cells, the so-called brown fat, responsible for metabolic burning, obtaining energy in the human body and converting it into heat.
We know that people with more brown fat have a lower risk of developing type 2 diabetes. With these results, the risk of developing type 2 diabetes and other obesity-related diseases can be reduced. It will be possible to stimulate the development of brown fat tissue and burn excess energy stored in the fat tissue in the form of heat, Prof. Enerbäck.
What is brown fat?
Swedish researchers called the newly discovered cells classic brown fat. Young people have them, but the tissue containing such cells disappears during maturation. Enerbäck’s team is researching to restore them, which would allow not only weight loss, but also a partial elimination of obesity-related diseases. According to Swedish researchers, the conversion is only 15 percent. white fat on brown fat cells would make it possible to safely lose weight of 4-5 kg per month. Currently, it is assumed that this level (i.e. weight loss without the yo-yo effect and without health consequences, i.e. the risk of causing gastritis or chronic disturbances in the functioning of the intestines and liver) is 1,5-2 kg per month. According to the researchers from the team of prof. Enerbäck, the miraculous diets that promise to lose 5-8 kg per month can cause permanent liver and intestinal dysfunction, including occurrence of irritable bowel syndrome.
Brown tissue composed of adipocytes is a type of specialized tissue that is involved in metabolic combustion and produces heat. It was first discovered in infants and small rodents, but mature specimens, like adults, also have it, albeit in a significantly reduced amount.
Meanwhile, earlier research than Swedish, conducted by scientists from Université de Sherbrooke and Université Laval in Quebec, led by Dr. André C. Carpentier and Dr. Denis Richard, proved that in adults brown fat tissue becomes activated only under extreme conditions, e.g. low temperatures. At room temperature, light cold and high temperatures, it does not burn energy at all.
Therefore, a team of scientists from Stockholm universitat, led by prof. Barbara Cannon and prof. Jan Nedergaard claims that the activities of doctors and scientists must be more comprehensive. It is not enough to cause the brown fat tissue to regenerate in the body, it also has to be induced to burn metabolic and generate heat in order to burn excess fat and to lose weight naturally in obese people. According to scientists from Stockholm Universitat, the key to this process is the classic brown fat, discovered by the team of Prof. Enerbäck, because probably these brown fat cells are not dependent on the temperature of the environment in which the person with them stays.
The presence of brown fat
In turn, a team of scientists from the Health Science Center at the University of Texas, led by Prof. Mikhaila Kolonina investigated the formation and disappearance of adipocytes that produce brown fat in an animal model. The team found that the ratio of brown fat to white fat, which only stores energy, is highest in hibernating animals such as bear and gopher. A sufficient amount of this type of adipose tissue provides them with the recovery from hibernation to sleep and normal activity. Thickness measurements for this type of tissue are unreliable. So far, we do not have an indicator of how exactly its distribution in the body looks like, because it occurs non-uniformly, and so every person has their own areas where adipocytes occur. Our research has allowed the isolation of peptides that dissolve only in brown fat – so they are a good measure of its presence in the body – told Science Prof. Kolonin.
Dr. Eva Sevick-Muraca working on the team developed a near-infrared emitter that emits short, intense infrared flashes that are captured by sensitive cameras located on the head of the device. The patient is given a pill with several types of peptides with a dye. These peptides are absorbed into the brown fat, dissolving the dye. Infrared radiation emissions define the areas where the dye is present, which is recorded by the device’s cameras. This way, you can tell where the tissue containing adipocytes is present.
Currently, the solution of Kolonin syndrome is undergoing clinical trials and, if it works properly, will be adopted as the first such measure of individual level of brown fat and its ratio to white fat in the body.
Meanwhile, a team of scientists from Harvard Medical School, working under the leadership of Prof. endocrinology scientist Aaron Cypess found that the areas of brown fat in the body were unusual. It lies deep in the adipose tissue, under the layer of superficial fat, and its amount, measurable by the protein found only in adipocytes, depends on the health of the person. Similarly, as Kolinin’s syndrome found, Harvard Medical School researchers also found that this fat was island-like from the front of the neck to the bottom of the chest. To make matters worse, their research shows that in some places it is associated with and partially mixed with white fat. At the cellular level, such a structure resembles marble. We wonder if brown fat cells cannot be grown directly at this level. Our first attempts show that it is possible – said prof. Cypess.
Scientists from his team have managed to produce brown fat from preadipocyte cells, i.e. pre-fat cells. They were obtained from cells from the patient’s neck undergoing surgery. In laboratory conditions, this process took two weeks, it would take less in the body itself. According to the researchers, the preadipocytes can turn into both white and brown fat. In the course of the experiment, scientists from Harvard Medical School also tried to measure metabolism, the amount of energy produced by brown fat, by calculating the amount of oxygen consumed by the tissue containing it, both in laboratory conditions, in cultured cell culture and in samples taken from volunteers. Brown fat was found to be the main type of tissue that produces heat. Its size could possibly be increased in an adult to the level it occurs in adolescence. According to prof. Cypessa would not mean a miracle diet to protect against obesity in all conditions, but an opportunity to treat the negative effects of overweight and obesity and – possibly – a kind of rejuvenation of the body by facilitating metabolic changes.
Tekst: Marek Mejssner