Apples Help Keep Muscles Strong, Mouse Study Finds

Discovery may lead to new treatments to prevent wasting due to aging, illness, researchers say

THURSDAY, June 9 (HealthDay News) -- A natural compound found in apples may help prevent muscle wasting that can result from aging and illness, according to the results of a study in mice.

The benefit appears to come from a compound in apple skin called ursolic acid, according to Dr. Christopher Adams, of the University of Iowa in Iowa City, and colleagues.

Adams and colleagues first identified 63 genes that change in response to fasting in both people and mice, and another 29 that change their expression in the muscles of both people who are fasting and those with spinal cord injuries. They then looked at 1,300 small molecules and zeroed in on ursolic acid as a compound that might counteract muscle atrophy.

In the next phase, the researchers found that ursolic acid could protect against muscle wasting in mice that were deprived of food. They also found that adding ursolic acid to the food of normal mice for a number of weeks prompted muscle growth.

In addition, mice that received ursolic acid became leaner and had lower blood levels of glucose, cholesterol and triglycerides, the investigators found.

The health benefits noted in the mice were due to enhanced insulin signaling in muscle and to corrections in gene signatures associated with muscle atrophy, the researchers explained.

"Ursolic acid is an interesting natural compound," Adams said in a journal news release. "It's part of a normal diet as a component of apple peels. They always say that an apple a day keeps the doctor away....People who eat junk food don't get this."

It is not clear whether the findings in mice will be confirmed in human trials, however, and whether the amount of ursolic acid consumed as part of a normal diet would protect against the ravages of muscle wasting.

The findings, published in the June issue of the journal Cell Metabolism, might lead to the development of new drugs if confirmed in humans, the study authors suggested.

"Muscle wasting is a frequent companion of illness and aging," Adams said. "It prolongs hospitalization, delays recovery and in some cases prevents people from going back home. It isn't well understood and there is no medicine for it."

More information

The U.S. National Library of Medicine has more about muscle atrophy.

Robert Preidt SOURCE: Cell Metabolism, news release, June 7, 2011

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