Compounding research suggests that apples can do a hell of a lot more than just keep the doctor away. Researchers at the University of São Paulo in Brazil recently tested the anabolic and protein-sparing effects of ursolic acid, a waxy substance particularly concentrated in apple peels. The in vitro study found that ursolic acid had a significant effect on skeletal muscle cells and directly promoted muscle protein increases.
This echoes the findings of a University of Iowa study published last year in the journal Cell Metabolism, which presented some truly groundbreaking results. When administered to mice affected by atrophy, ursolic acid halted muscle degradation; when the scientists gave it to healthy mice, they developed larger, stronger muscles. Not only that—ursolic acid also reduced body fat, blood glucose levels, cholesterol, and triglycerides.
The researchers determined that ursolic acid’s anabolic effects are the result of its ability to modulate two key muscle-building hormones: insulin and insulin-like growth factor-1 (IGF-1), both of which bind to muscle cell receptors and set off a chain reaction, initiating pathways associated with enhancing muscle growth and blocking atrophy. These processes are amplified by ursolic acid, which binds to the same receptors.
Additionally, apples contain pectin, a soluble fiber that lowers appetite and promotes the feeling of fullness. It also limits the amount of fat that cells can absorb. The obvious lesson here is to eat more apples, and when you do, make sure to leave the peel on. Give it a quick wash, though.
REFERENCE: V.C. Figueiredo and G.A. Nader, Cell Biochem Funct., 10.1002/cbf.2821; E-pub March 13, 2012.