The fat directly on the heart makes more harmful chemicals than the fat around blood vessels, and this matches with it having more of the enzyme MAO-A.
Scientific Claim
Human epicardial adipose tissue produces higher levels of reactive oxygen species than perivascular adipose tissue under baseline conditions, correlating with higher MAO-A expression in epicardial fat.
Original Statement
“A higher intensity of the DHE stain (arbitrary units) was present in EAT as compared to PVAT, a result that recapitulates the observation on MAOs expression in the two types of adipose tissues presented in Fig. 1. ... H2O2 production ... was significantly reduced in the presence of MB in both types of adipose tissues, apparently in a higher degree in EAT as compared to PVAT.”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
definitive
Can make definitive causal claims
Assessment Explanation
The comparison was made within the same patient cohort using standardized assays. The claim accurately describes the observed differences without implying causation or generalizability beyond the sample.
Evidence from Studies
Supporting (1)
Methylene blue reduces monoamine oxidase expression and oxidative stress in human cardiovascular adipose tissue
The study found that a specific enzyme (MAO-A) in heart fat makes harmful molecules called ROS, and this enzyme is especially active in the fat around the heart — which matches the claim that this fat makes more ROS because it has more of this enzyme.