Thanks to Popeye, spinach is the food most associated with muscle strength in the public mind — and indeed, preliminary research suggests a plant steroid in spinach may significantly support muscle growth.  Now, a new study points to a compound found in apple peels — called ursolic acid — that may have similar benefits.

Researchers from the University of Iowa
 added this compound to the diet of mice for over five weeks, then compared their muscle health to those of a control group.They found that the ursolic-fed mice enjoyed 16% less muscle loss and a marked 22% increase in grip strength.One possible explanation: The muscles of the ursolic-mice grew dramatically leaner, reducing muscle fat content by 70%! This suggests benefits not just for biceps, but for internal organs as well: excess dietary fat can ultimately make it into the heart where fat molecules actually kill heart muscle.Moreover, the ursolic acid diet resulted in over a 25% drop in both cholesterol and triglycerides, both of which can undermine heart health.These are encouraging results, not just for body-builders, but for the rest of us, who begin losing muscle in our late 20’s and early 30’s, and especially for the estimated 17% of seniors affected by sarcopenia, a debilitating loss of muscle mass that can limit mobility. While more research is needed to determine whether ursolic acid — and its food sources — would benefit humans, it’s safe to say that adding more apples to your diet will support overall health.The apple compound quercetin has been linked to increased stamina and possible reduced risk of various diseases. While all apples are good for you, the Red Delicious variety packs the biggest phytochemical punch.

Bonus: Weight lifting can also be effective in preserving muscle mass, regardless of how old you are. Bigger biceps have also been linked to significantly lower odds of mortality in one 6-year study.

Published July 1, 2011