The benefits and harms of brown fat

Brown fat harms blood vessels

Kirill Stasevich, CompulentaWe used to think of brown fat as something absolutely good.

Of course, unlike white fat, it does not accumulate lipids, but, on the contrary, burns them, directing the released energy to heating the body. The hopes of defeating obesity are connected with brown fat: if we learn to activate this type of adipose tissue at will, the problem of overweight (and accompanying cardiovascular and metabolic diseases) will be removed.

But brown fat also has negative effects, and, most unexpectedly, they manifest themselves again in relation to the unfortunate cardiovascular system.

In winter, people die of heart attacks more often than at other times of the year. It was believed that this was due either to general physical inactivity, which begins in the winter months, or to excessive snow removal efforts, which cause overstrain of the heart. All this, however, remained nothing more than assumptions. Scientists from the Karolinska Institute (Sweden) together with colleagues from Shandong University (China) tried to clarify this issue.

As mentioned above, brown fat plays an important role in thermoregulation: when it is cold, it burns the lipid reserves accumulated in white fat. It would be logical to assume that the cold can make us slim and healthy. Researchers led by Yi Hai Cao, who experimented with mice, thought the same way: animals with a predisposition to atherosclerosis were kept in the cold, expecting that mice would only be healthier from this, because lipids that are deposited on the walls of blood vessels should be burned with brown fat.

It turned out to be the opposite. In the cold, the growth of atherosclerotic plaques on the walls of blood vessels only intensified, and these plaques themselves were unstable, easily detached and began to float along the bloodstream, threatening blockage of blood vessels.

In an article published in the journal Cell Metabolism (Dong et al., Cold Exposure Promotes Atherosclerotic Plaque Growth and Instability via UCP1-Dependent Lipolysis), the authors write that this was precisely due to the activity of brown fat, which, by splitting fats, increased the proportion of harmful low-density lipoproteins in the blood. And it was possible to protect mice from increased atherosclerosis by turning off the UCP1 protein in them.

That is, brown fat, of course, helps to get rid of excess fat reserves, but in return it increases the likelihood of atherosclerosis. If these results are confirmed in human studies, then the general praises of brown fat will probably subside — scientists will have to work on how to deprive brown fat of this unpleasant side effect.

Prepared based on the materials of the Karolinska University:
Brown fat responsible for from heart disease-related deaths in winter.

Portal "Eternal youth" http://vechnayamolodost.ru04.07.2013