Substrate Utilization by Brown Adipose Tissue: What's Hot and What's Not?
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing mechanistic and physiological literature without systematic review methodology
PubMed 33101206 · doi:10.3389/fendo.2020.571659
What was done
This narrative review summarizes human and rodent evidence on brown adipose tissue (BAT) substrate utilization during cold-induced thermogenesis, focusing on findings enabled by non-invasive metabolic tracer imaging techniques such as positron emission tomography.
What was found
The abstract reports no numerical data. Qualitatively, it describes that while BAT markedly increases glucose uptake during thermogenesis, much of this glucose is converted to lactate rather than completely oxidized. Fatty acids derived from internal brown adipocyte triglyceride stores and circulating lipids serve as the primary fuel source, with additional regulation provided by glycolytic and tricarboxylic acid cycle intermediates.
Why it matters
Clarifying how human BAT utilizes various energy substrates provides physiological context for evaluating BAT activation as a metabolic target for type 2 diabetes, dyslipidemia, and obesity.
Limits
The paper is a narrative review with no original data, systematic search protocol, or quantitative meta-analysis. Mechanistic pathways described often rely on rodent models, which possess higher relative BAT mass and energy expenditure contribution than adult humans.
Cited by
- supports Under fasted conditions, cold-induced thermogenesis relies on breaking down triglycerides and oxidizing free fatty acids in the mitochondria to produce heat.