Glutathione and Fuel Oxidation in Aging

Glutathione is an important antioxidant protein which protects cells from harmful oxidative stress. Elderly humans are known to have elevated oxidative stress and deficiency of glutathione, but it is not known whether there is deficient synthesis of glutathione in muscle tissue of elderly humans. Mitochondria are engines of cells where food consumed is burned to make energy. Under normal conditions the fuel of choice in the fasted state is fat, but fasted elderly humans are not able to oxidize fat as well as healthy young humans. Elderly humans also have the highest incidence and prevalence of being overweight and obese, and have increased storage of fat in liver and muscle. This study will help determine whether 1. elderly humans have diminished synthesis of glutathione in the skeletal muscle, and whether this can be improved by supplementing cysteine and glycine (and not an isonitrogenous placebo) in the diet; 2. improving muscle glutathione concentrations can also improve fuel oxidation in aging; 3. improvement of intracellular glutathione concentrations will be associated with a change in total body fat content