Researchers at the University of Iowa have discovered that a waxy substance known as ursolic acid found in the apple peel reduces muscle atrophy and promotes muscle growth in mice.
It is also found to reduce fat, blood sugar levels, cholesterol and triglycerides, hence, can be used in treating muscle wasting and metabolic disorders such as diabetes. "Muscle atrophy causes big problems. It's also very common - it affects most people at some point in their lives, during illness or aging. But, there's no medicine for it," said Christopher Adams, endocrinologist and senior author of the study.
"We studied muscle gene activity in people with atrophy and used that information to find chemicals that might block atrophy. One of those chemicals was especially interesting. It's called ursolic acid and it's particularly concentrated in apple peels, he added.
According to the researchers, ursolic acid reduced muscle atrophy by helping insulin-like growth factor-1 (IGF1) and insulin to build muscles. "It did this by helping two hormones that build muscle: insulin-like growth factor-1 (IGF1) and insulin. Because ursolic acid increased muscle, it reduced muscle atrophy. Surprisingly, it had some other beneficial effects in mice: for example, it reduced body fat, and lowered blood glucose and cholesterol."
Additionally, although ursolic acid increased muscle weight in mice, it did not increase total body weight. Furthermore, mice fed ursolic acid were found to have less body fat than mice that were not fed the compound.
The study has been published in the current issue of the journal Cell Metabolism .