Brown Fat Helps Clear TriglyceridesWednesday, January 26, 2011
Regular readers may recall that recently brown adipose tissue, long thought to be only present in new born infants, is also present in varying amounts in human adults.
Furthermore, variations in the amount of brown adipose tissue, which is primarily a heat-generating organ, can contribute to substantial variations in daily total energy expenditure between individuals.
To produce heat, brown adipose tissue directly burns fatty acids derived from circulating triglycerides.
Now Alexander Bartelt and colleagues from the University of Hamburg-Eppendorf, Germany, in a paper just published in Nature Medicine, demonstrate that this property of brown adipose tissue can significantly contribute to clearance of triglycerides from the blood stream.
In their studies, the researchers stimulated activity of brown adipose tissue in mice by exposing the animals to low temperatures. Cold exposure drastically increased clearance of triglycerides via increased uptake into brown adipose tissue and corrected increased lipid levels in insulin resistant mice.
Given that elevated plasma triglyceride concentrations, especially in diabetic dyslipidemia, is an important risk factor for cardiovascular disease, activation of brown adipose tissue may be a novel therapeutic approach to reduce elevated triglyceride concentrations.
Of course, increasing brown adipose tissue would perhaps also help burn excess calories, thereby reducing the risk of obesity.
Unfortunately, the best known way to increase brown adipose tissue activity is to increase sympathetic nervous activity, a side effect of which may be an increase in heart rate and blood pressure.
On the other hand, short burst of cold exposure may suffice to stimulate brown adipose tissue activity, without persistent effects on sympathetic activity. Whether such cold exposure can indeed improve triglycerides levels and help burn extra calories in humans remains to be seen.
Thankfully, with our winters here in Edmonton, I am in the right place to get plenty of cold exposure for free.
Bartelt A, Bruns OT, Reimer R, Hohenberg H, Ittrich H, Peldschus K, Kaul MG, Tromsdorf UI, Weller H, Waurisch C, Eychmüller A, Gordts PL, Rinninger F, Bruegelmann K, Freund B, Nielsen P, Merkel M, & Heeren J (2011). Brown adipose tissue activity controls triglyceride clearance. Nature medicine PMID: 21258337