UTMB Researchers Show that Brown Fat Affects Glucose Metabolism in Humans

Research first-authored by Maria Chondronikola, a registered dietitian, shows that brown adipose is an anti-diabetic tissue in humans. The principal investigator of this ground-breaking research is Dr. Labros Sidossis, will teach a course on obesity in my Master of Science/Dietetic Internship program in the Fall 2014 semester.  

Uncoupling proteins allow hydrogen to cross the membrane without
making ATP; this causes the energy to be lost as heat.

Brown fat cells are different from white fat cells because they are rich in mitochondria containing a lot of uncoupling proteins (UCP).   When our bodies use food for energy, the food energy is used to make a proton gradient in the mitochondria to transfer food energy to ATP, the molecule our bodies use to do work. Uncoupling proteins disrupt the gradients in brown fat cells and allow food energy escape as heat.  In other words, brown fat cells allows us to 'burn calories' to make heat instead of storing energy in the body.

Babies have relatively more brown adipose tissue than adult humans.  Brown fat is found in adults in some areas around the neck and a few other places. Scientists activate

The middle row shows brown fat activation 

with cold exposure on a PET can in 

research performed by Virtanen and others.

brown fat in research by exposing subjects to just the right amount of cold, promoting 'non-shivering thermogenesis.' Adults seem to have more brown fat when they are lean, younger, and female, while older people and those with diabetes or a high BMI tend to have less brown fat.  It seems that aging probably causes a loss of brown fat. The causal relationships between brown fat and obesity and diabetes still need to be determined.  Emerging research shows that exercise and dietary compounds, like capsaicin, may activate brown fat in the short term.

The research done at UTMB is new because scientists matched subjects for factors like age and overall body fat content and separated groups into brown fat + and brown fat -.  The scientists exposed all the research subjects to a cold environment, but only brown fat positive (+) showed increased calorie burning, sugar storage, and insulin sensitivity with cold exposure.  More research needs to be done to see if nutrition, exercise training or other interventions can promote greater brown fat content or activity for the long term.

References

Research by UTMB Scientists

Article source of PET scan image: Functional Brown Adipose Tissue in Healthy Adults

Article source of UCP image: The role of the uncoupling protein 1 (UCP1) on the development of obesity and type 2 diabetes mellitus

The presence of UCP1 demonstrates that metabolically active adipose tissue in the neck of adult humans truly represents brown adipose tissue

Impact of Age on the Relationships of Brown Adipose Tissue With Sex and Adiposity in Humans

Outdoor Temperature, Age, Sex, Body Mass Index, and Diabetic Status Determine the Prevalence, Mass, and Glucose-Uptake Activity of ¹⁸F-FDG-Detected BAT in Humans

Nonpungent capsaicin analogs (capsinoids) increase energy expenditure through the activation of brown adipose tissue in humans

Exercise as a new physiological stimulus for brown adipose tissue activity