September 18, 2008

A Lower Calorie Diet May Help Save Muscle

A restricted-calorie diet, started in early adulthood, may stymie a mitochondrial mishap that may add to muscle loss in aging adults, U.S. researchers said.

Senior author Christiaan Leeuwenburgh of the University of Florida College of Medicine said that in rats, the scientists found pockets of excess iron in muscle cell mitochondria -- the tiny power plants found in every cell.

"We become less efficient at an old age and we need to understand why this is," Leeuwenburgh said in a statement. "One thing, maybe, is the accumulation of redox-active metals in cells. If the mitochondria become unhappy or are ready to kick the bucket, they have proteins in the inner and outer membranes that they can open up and commit suicide. They're tricky beasts."

The researchers found increasing amounts of iron in the muscle cells of aging rats fed a typical unrestricted diet, but the older the rats got, the more iron accumulated in the mitochondria and the more damage was done.

However, the study, published in the the journal PLoS One, found rats of the same age that were kept on a calorie-restricted diet -- about 60 percent of the food typically ingested -- seemed to maintain more normal iron levels in mitochondria.