The fatty layer on an apple peel contains a compound that has an anabolic effect, write researchers from the University of Iowa. It’s called ursolic acid, but also goes by the shorter name of malol. In tests on mice, the compound caused their muscles to grow and fat mass to shrink.
Ursolic acid is also present in basil, blueberries, cranberries, rosemary, oregano, thyme and plums. And speaking of plums: researchers at the American department of agriculture discovered in 2006 that prunes (dried plums) boost the concentration of IGF-1. They had no explanation for this, but it might be that ursolic acid explains the special effects of prunes.
The researchers from Iowa stumbled upon the anabolic properties of ursolic acid when they were examining cells from muscle tissue that was wasting. They determined which genes in the cells were active during the process of muscular atrophy. Then they searched databases for substances that had the opposite effect. The most promising substance they found was ursolic acid.
The researchers gave this to fasting mice and observed that the ursolic acid led to a reduction in the processes of muscle atrophy. They then did a second round of experiments, in which the mice were given as much to eat as they wanted. A control group was given ordinary feed and another group was given feed containing 0.27 percent ursolic acid.
A five-week course of ursolic acid resulted in growth of the quadriceps and the mice grew stronger. The activity of the catabolic genes MuRF-1 and Atrogin-1 declined in the muscle cells. In contrast, the activity of the gene for IGF-1 increased, as did the concentration of IGF-1 in the blood. Molecular signaling molecules, like the receptor for IGF-1, Akt and S6K, were switched on.
In the animal studies ursolic acid also reduced the fat cells’ emission of leptin, the concentrations of triglycerides and cholesterol, and even the fasting glucose level. All of these are positive effects.
The researchers suspect that ursolic acid’s prime target is the IGF-1 receptor. This becomes more sensitive and as a result the IGF-1 that is present in the body works better.
Dominick Walsh is a blogger for Performance Nutrition and TMRzoo.com and covers all men’s health topics and exercise issues including protein powders, diets, weight loss, weight lifting supplements, fat burners and supplement reviews. Dominick’s columns cover everything you need to know about your pre, during and post workout nutrition.