A waxy substance found in apple peels may promote muscle growth and the prevent muscle wasting that is a hallmark of aging, fasting or illness, a new study in mice suggests.
Mice given the compound, called ursolic acid, became leaner and had lower blood levels of glucose, cholesterol and triglycerides. The findings therefore suggest that ursolic acid may be responsible for some of the overall benefits of healthy eating, the study said.
Further, the results suggest the compound is a promising drug candidate to treat muscle wasting, the researchers said. Currently, there are no drugs for the condition.
More studies need to be done to determine whether the findings translate to humans. In addition, the researchers aren't sure whether ursolic acid consumed through the diet may be enough to have the effects seen in the study.
Muscle wasting, or atrophy, is loss of muscle tissue. Such atrophy can result from a lack of physical exercise (for example, when someone is bedridden due to illness). Certain diseases, such as amyotrophic lateral sclerosis (ALS), which affect the nerves that control muscle, can also cause muscle atrophy.
"Muscle wasting is a frequent companion of illness and aging," said study researcher Dr. Christopher Adams, an endocrinologist at the University of Iowa. "It prolongs hospitalization, delays recoveries and in some cases, prevents people from going back home," Adams said.
Adams and his colleagues examined which genes in muscle cells were turned on and off as a result of the fasting, and identified ursolic acid as a compound that would counteract these genetic changes.
They also fed ursolic acid to mice that were fasting and found the compound protected against muscle weakening. In healthy mice, it promoted muscle growth.
The researchers hope to test the compound in trials with people.
The study was funded by the Department of Veterans Affairs, the American Diabetes Association and the University of Iowa Research Foundation, among others.
The findings are published in the June issue of the journal Cell Metabolism.
Pass it on: A substance in apple peels may protect against muscle wasting.