People with obesity face a significantly increased risk of atherosclerosis, and consequently heart attack and stroke. This elevated risk is largely driven by chronic inflammation in the blood vessels, which is more common in severe obesity. A new study led by Florian Kiefer at the Division of Endocrinology and Metabolism, MedUni Vienna, has now identified brown adipose tissue (brown fat) as a potential protective factor for vascular health. The findings, published in Atherosclerosis, Thrombosis and Vascular Biology, show for the first time in humans that individuals with obesity and active brown fat exhibit significantly lower arterial inflammation.

The study, conducted by a research team led by Florian Kiefer (Division of Endocrinology and Metabolism, Department of Medicine III, MedUni Vienna) and Oana Kulterer (Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy, MedUni Vienna) included 65 adults with obesity. Brown adipose tissue activity was assessed using 18F-FDG-PET/CT imaging following standardized cold exposure. This technique uses a radiolabeled glucose tracer to identify metabolically active tissues. At the same time, inflammatory activity was measured in different sections of the aorta.

More brown fat activity, lower vascular inflammation, and a healthier blood profile
Approximately one-third of participants showed detectable brown fat activity after cold stimulation. These individuals had significantly lower inflammatory activity in the aorta compared to those without active brown fat. Moreover, the study found a clear association: higher brown fat activity correlated with lower levels of vascular inflammation. Blood analyses further supported these findings, showing increased levels of anti-inflammatory and vasoprotective molecules in individuals with active brown fat. At the same time, markers linked to inflammation and atherosclerosis were reduced.

"In this study, we demonstrate for the first time that people with obesity who have active brown fat show less inflammation in the aortic vessel wall than comparable individuals without this tissue," said principal investigator Florian Kiefer from the Division of Endocrinology and Metabolism at MedUni Vienna.

Brown adipose tissue is a vital organ for heat production in newborns and infants but its quantity and activity decline with age and are typically reduced in obesity. Unlike white fat, which stores energy, brown fat burns energy and plays a role in heat production.
"Our findings suggest that brown fat may not only benefit metabolic health but could also act as a protective factor for the vascular system,” Kiefer added. “While brown fat is primarily activated by cold exposure, research is already exploring pharmacological strategies to stimulate its activity."

The study was conducted in collaboration with the Division of Nuclear Medicine at MedUni Vienna and the Institute of Analytical Chemistry at the University of Vienna. Further long-term studies are planned to confirm these results and to investigate whether targeted activation of brown adipose tissue could help reduce cardiovascular complications in people with obesity.