In the last 2-3 years there is has been a lot of excitement in research circles about brown adipose tissue, in other words, brown fat. Brown fat, long known to exist plentifully in babies and rodents, is rich in turned-on mitochondria and blood vessels. Unlike white fat, brown fat burns energy at a ferocious rate. In adults, however, it tends to be scarce and concentrated around the neck and has been traditionally thought to play a relatively minor role in adult human metabolism. The newer research suggests a different picture. Brown fat can be very important for metabolism. Further, the creation of brown fat can be induced by turning on a certain gene and that induction of brown fat could possibly play a major role in public health by controlling or even eliminating obesity.
About brown fat
Brown fat keeps tiny critters in the wild warm and is important for us too. “Cold-induced adaptive (or nonshivering) thermogenesis in small mammals is produced primarily in brown adipose tissue (BAT). BAT has been identified in humans and becomes more active after cold exposure. Heat production from BAT requires sympathetic nervous system stimulation, T3, and uncoupling protein 1 (UCP1) expression(ref).” When animals are exposed to cold, the expression of the UCP1 gene is upregulated to activate the production of heat. UCP1, also known as thermogenin, “allows the leak of protons in respiring mitochondria, dissipating the energy as heat; the enzyme has an important role in nonshivering heat production induced by cold exposure or food intake(ref).”
A little brown fat can go a long way towards burning food energy and total metabolism. “Brown fat cells have been found in adults, in the lower part of the neck just above the collarbone. The region of brown fat cells in the neck was tested by placing five volunteers, in thin clothing, in a chilly room for a couple of hours. The researchers then investigated this region by PET scanning and discovered that metabolism there was on average 15 times higher than in the neighboring white fat tissue. The result suggests that the brown fat may play a significant role in metabolism(ref).”
So, researchers have reckoned that if they could find a safe and easy way to increase the ratio of brown fat to white fat in adults, that might go a long way towards having a skinnier, healthier less-obese population. “It has been suggested that manipulating the development of fat cells so that they become brown fat cells rather than white fat cells might be an approach to treat obesity(ref).”
Recent research related to creating brown fat
A number of important discoveries have been made, one reported today in a news item in Science Daily Brown Fat Cells Make ‘Spare Tires’ Shrink; Promising New Approach to Combat Obesity. “Scientists at the University of Bonn have found a new signaling pathway which stimulates the production and function of so-called brown fat cells. They propose using these cells that serve as a “natural heating system” in order to just ‘burn’ unwanted excess fat. — The scientists were now able to show which signals prompt the body to produce brown fat cells. A signaling pathway which is controlled by the PKG enzyme takes on a key role in this process. This signaling pathway results in the stem cells of the fatty tissue becoming brown fat cells. For this it switches on the mass production of mitochondria and ensures that UCP is formed — . — Furthermore, we were able to show that PKG makes brown fat cells susceptible to insulin,” –. “Therefore PKG also controls how much fat is burnt in general.”
This research result follows an important discovery in 2008 that myoblasts, muscle cell progenitor cells, can not only differentiate so as to produce replacement muscle cells when activated by appropriate signals, but also can differentiate to produce brown fat cells when a gene called PDRM16 is turned on(ref)(ref). See Making ‘Good’ Fat From Muscle And Vice Versa.
This followed a discovery in 2007 that when PRDM16 genes are inserted into white fat precursors, the precursor cells produce brown fat cells instead of white ones(ref)(ref). “Spiegelman (the lead researcher in this work) said the finding confirms that PRDM16 is the “master regulator” of brown fat development(ref).” Finding a drug or supplement that activates the PRDM16 gene is therefore a possible strategy for controlling weight and obesity in humans. Another possibility might involve “transplanting PRDM16-equipped white fat precursors into people who are at high risk of becoming obese, to shift their metabolism slightly into a calorie-burning mode(ref).”
Are there dietary supplements that differentially promote the creation of brown fat and therefore higher metabolism so as to control weight? Quite possibly, but my impression is that research in this area is just getting off the ground now. I have seen several supplement-vending sites that talk about brown fat and vaguely suggest that their supplements may help create it – but they provide no research backup for such claims. Doing some quick and possibly superficial searching, I found relevant research on only one supplement, the amino acid l-arginine. Several studies suggest that l-arginine increases lean body mass in obese rats. And the title of this 2009 publication tells its basic story: Dietary L-arginine supplementation reduces white fat gain and enhances skeletal muscle and brown fat masses in diet-induced obese rats. L-arginine is sometime advertised as a weight loss substance, as a sexual stimulant, and (combined with other amino acids) as a promoter for the expression of human growth hormone. Because of a bad experience I had resulting from heavy use of l-arginine several years ago (a bout of arthritis), I have since personally avoided it.
I expect to see a number of additional research publications on dietary supplements and brown fat in the coming year or two and will report on these as I come across them.