Vitamin A boosts fat burning in cold conditions
The conversion of white into brown adipose tissue is a promising target
for obesity treatment

Date:
October 21, 2020
Source:
Medical University of Vienna
Summary:
A recent study shows that cold ambient temperatures increase
vitamin A levels in humans and mice. This helps convert 'bad' white
adipose tissue into 'good' brown adipose tissue which stimulates
fat burning and heat generation.



FULL STORY ==========================================================================
A recent study conducted by a research team led by Florian Kiefer from
MedUni Vienna's Division of Endocrinology and Metabolism shows that cold ambient temperatures increase vitamin A levels in humans and mice. This
helps convert "bad" white adipose tissue into "good" brown adipose
tissue which stimulates fat burning and heat generation. This "fat transformation" is usually accompanied by enhanced energy consumption
and is therefore considered a promising approach for the development
of novel obesity therapeutics. The study has now been published in the
journal Molecular Metabolism.


==========================================================================
In humans and mammals, at least two types of fatty depots can be
discerned, white and brown adipose tissue. During obesity development,
excess calories are mainly stored in white fat. In contrast, brown fat
burns energy and thereby generates heat. More than 90% of the body fat
depots in humans are white which are typically located at the abdomen,
bottom, and upper thighs. Converting white into brown fat could be a
new therapeutic option to combat weight gain and obesity.

A research group led by Florian Kiefer from the Division of Endocrinology
and Metabolism, Department of Medicine III at MedUni Vienna demonstrated
now that moderate application of cold increases the levels of vitamin
A and its blood transporter, retinol-binding protein, 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 led to a
conversion of white fat into brown fat ("browning"), with a higher rate
of fat burning.

When Kiefer and his team blocked the vitamin A transporter
"retinol-binding protein" in mice by genetic manipulation, both the cold-mediated rise in vitamin A and the "browning" of the white fat
were blunted: "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 Kiefer. In contrast, the addition of vitamin
A to human white fat cells led to the expression of brown fat cell characteristics, with increased metabolic activity and energy consumption.

"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 the MedUni Vienna
researcher. "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." Scientists from Harvard University, Boston
and Rutgers University, New Jersey were also involved in the study. The
study was funded by the Austrian Science Fund (FWF), the Vienna Science
and Technology Fund (WWTF) and the research fund of the Austrian Diabetes Society.


========================================================================== Story Source: Materials provided by Medical_University_of_Vienna. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Anna Fenzl, Oana Cristina Kulterer, Katrin Spirk, Goran
Mitulović,
Rodrig Marculescu, Martin Bilban, Sabina Baumgartner-Parzer,
Alexandra Kautzky-Willer, Lukas Kenner, Jorge Plutzky, Loredana
Quadro, Florian W.

Kiefer. Intact vitamin A transport is critical for cold-mediated
adipose tissue browning and thermogenesis. Molecular Metabolism,
2020; 101088 DOI: 10.1016/j.molmet.2020.101088 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201021112318.htm

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