Vitamin A Boosts Fat Burning in Cold Conditions by Turning White Fat Into Brown Fat
A recent study examines the possibility of using Vitamin A for weight loss by turning obesity-based white fat into energy-burning brown fat under cold conditions.
Brown Fat Reduces Obesity
According to a news release from the Medical University of Vienna, in humans and other mammals, fatty tissue comes in two types: white fat and brown fat. The white fat is the result of an excess of calories in a diet that leads to accumulation of more than 90% of all fat in the body, typically concentrated in the abdomen, buttocks and upper thighs.
Brown fat on the other hand, is much less abundant and can typically be found in the neck and shoulders as well as among white fat stores. The importance of brown fat is that it is mitochondria-rich, which results in brown fat tending to burn energy and produce heat, rather than lie dormant in the body like white fat.
As it turns out, brown fat is actually made from white fat, and earlier studies have shown that brown fat reduces obesity. The significance of this is that if white fat could be therapeutically controlled to transform into brown fat, then obesity would no longer be the serious health problem it is now.
Vitamin A Could Control Brown Fat Transformation
Today, Medical University of Vienna researchers report that controlling the conversion of white fat into brown adipose tissue is a possibility by taking advantage of a role vitamin A plays in the thermogenic programming of fat tissue. Vitamin A metabolites—called “retinoids”— have been linked to thermogenic programming of fat tissue, whose expression can be stimulated under cold exposure conditions.
The published study tells us that, “…moderate application of cold increases the levels of vitamin A and its blood transporter, retinol-binding protein [Rbp], in humans and mice. Most of the vitamin A reserves are stored in the liver, and cold exposure seems to stimulate the redistribution of vitamin A towards the adipose tissue. The cold-induced increase in vitamin A leads to a conversion of white fat into brown fat (“browning”), with a higher rate of fat burning.”
Their theory on taking advantage of vitamin A’s properties in fat cells are from experiments performed on mice that were genetically engineered to be defective in the vitamin A transport protein Rbp (Retinol binding protein). Under cold environmental conditions, these mice were found to have suppressed thermogenic programming of their fat cells as well as suppressed oxidative mitochondrial function, which resulted in the mice being cold sensitive.
"As a consequence, fat oxidation and heat production were perturbed so that the mice were no longer able to protect themselves against the cold," explains Florian Kiefer, the lead scientist of the study and one of the co-authors.
However, when human cells possessing an intact vitamin A transport system were exposed to cold environmental conditions, retinoid expression increased and was associated with a shift in oxidative metabolites suggestive of higher lipid utilization; on in other words, increased brown fat burning.
These findings led the researchers to conclude that:
Systemic vitamin A levels are regulated by cold exposure in mice and humans, and intact retinoid transport is essential for cold-induced adipose tissue browning and adaptive thermogenesis.
"We have discovered a new mechanism by which vitamin A regulates lipid combustion and heat generation in cold conditions. This could help us to develop new therapeutic interventions that exploit this specific mechanism,” says Kiefer.
A Warning About Taking Vitamin A Supplements
However, this does not mean that now is the time to start stocking up on vitamin A supplements hoping that this will cause more of your white fat cells to turn into energy burning brown fat cells while out and about in the elements this winter. The take home message here is that you can expect to see weight loss advertisements coming out promoting vitamin A supplements as a weight loss aid based on this study. However, the authors of the study warn that this may not work and is not recommended based on what their studies have shown.
"Our results show that vitamin A plays an important role in the function of adipose tissue and affects global energy metabolism. However, this is not an argument for consuming large amounts of vitamin A supplements if not prescribed, because it is critical that vitamin A is transported to the right cells at the right time," explains Kiefer.
Furthermore, like everything else, the poison is in the dose. While levels of up to 10,000 IU (3,000 micrograms) have been considered safe; beyond that, vitamin A levels can build up and cause liver damage and brain swelling. Pregnant women who ingest too much Vitamin A also run the risk of fetal damage.
For more about the battle against fat, here is an informative article where a Study Suggests That Having Fat Thighs Actually Confers a Health Benefit.
Timothy Boyer has a Ph.D. in Molecular and Cellular Biology from the University of Arizona. For 20+ years he has been employed as a freelance health and science writer. Today, with an eye on the latest news, Timothy continues writing about science with a focus on what you need to know for healthier living. For continual updates about health, you can also follow Timothy on Twitter at TimBoyerWrites.
Image Source: Courtesy of Vic on Unsplash
“Vitamin A boosts fat burning in cold conditions” Medical University of Vienna news 21 Oct. 2020.
“Intact vitamin A transport is critical for cold-mediated adipose tissue browning and thermogenesis” Anna Fenzl et al. Molecular Metabolism, Available online 28 September 2020.