A controlled-calorie diet in early adulthood may stem muscle wasting later in life. Muscle wasting is just one part of the aging process, and presents a significant problem for aging adults.
University of Florida researchers have studied how mitochondria (a muscle cell) and the excess muscle iron found in it affects its ‘life-span’: Excess iron in the mitochondria initiates the formation of free radicals, which causes cell death.
Mitochondria are referred to as “cellular power plants” because they supply cellular energy through a series of chemical conversions. Their role in the aging process has been suspected but uncertain until now. Christian Leeuwenburgh, a UF professor of aging in the UF College of Medicine and the Institute on Aging was the senior author of the study. He said: ”We become less efficient at an old age and we need to understand why this is. 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 damage done by mitochondria extends to the entire muscle, which is strongly implicated in muscle wasting.
Leeuwenburgh added: “Muscle is critical for your overall well-being. As you walk, muscle functions partly as a pump to keep your blood going. Muscle is an incredible source of reserves.”
The research focussed on the effects of increasing quantities of iron in the muscle cells of aging rats. The group of rats fed an unrestricted diet were found to suffer from an accumulation of iron in the mitochondria, harming the RNA and DNA. A separate group of rats of the same ages were given a calorie-controlled diet that amounted to 60% of the total usually eaten. This group were found to benefit from the restricted food intake as they maintained stable iron levels in mitochondria.
Scientists are not sure why iron gathers in mitochondria, however, Leeuwenburgh suggests tracing the breakdown of how iron is transported through cells may provide the answer. Once the link has been determined, scientists will have a better understanding of how to combat this part of the aging process.
Mitch Knutson, co-author of the study explained: “The novel thing here is that iron is accumulating in places it does not normally accumulate. Such iron accumulation in muscle was quite unexpected. This may be of concern because more people are genetically predisposed to developing iron overload than we originally thought.”
When the iron in mitochondria reacts with oxygen, the iron can change the oxygen’s structure, causing free radical reactions within the muscle. Professor Leeuwenburgh describes this as “sort of like internal rust”.
Leeuwenburgh said: “Not all free radicals are harmful. To just use antioxidants to neutralize all free radicals is a huge misconception because some radicals are helpful. You just need to try and target very specific free radicals that form in specific parts of the body.”
Mitochondria are also implicated in several human diseases, including mental disorders, and cardiac dysfunction.