BAT: Brown Adipose Tissue in Humans - An Update

In the latest edition of Current Opinion in Lipidology we find a mini-summary (COL. 2010) on current findings on the existence and metabolic purpose of brown adipose tissue (BAT) in human beings. These days the previously accepted position that adults have little to no BAT is put into question by the results of PET, where brown fat becomes especially visible upon cold exposure, when its metabolic activity is increased as a result of thermogenesis.

The author points out that adipocytes (fat cells) and myocytes (muscle cells) do not only share the same origin, the metabolically active BAT exhibits other similarities to muscle cells, as well - it is a metabollically active tissue and of particular importance in the context of insulin sensitivity and glucose disposal:

BAT glucose uptake rate is 10-15-fold higher in cold than in normal room temperature. Other factors that may increase the activity of sympathetic nervous system and uncoupling protein 1 are several including the complex network of hormonal and neuronal signals. Preliminary results suggest that BAT resembles skeletal muscle not only by origin but also by the effect of insulin on the tissue.

Doubtlessly, more research has to be done on the issue of BAT vs. WAT (white adipose tissue) and their relation to obesity, diabetes and the metabolic syndrome. In spite of that, even what we know today suggests that a better understanding of this hitherto overlooked remainder from the days when our ancestors ran around naked could help to find a solution for some of the "fat" health problems of the western societies.