Panels A and B show data from female C3B10F1 mice subjected to restricted caloric intake (40, 50, or 85 kcal per week) starting at one month of age. The maximal life span (inset, Panel B) is the mean survival for the longest-lived decile of each group. Panels C and D show data from male B10C3F1 mice subjected to restricted caloric intake (90 kcal per week) as compared with control mice (160 kcal per week), starting at 12 months of age. Caloric restriction at both ages extended both average and maximal life span. Each symbol in the survival curves (Panels B and D) represents one mouse. The bars in Panels A and C represent standard deviations. (Data in panels A and B are from Weindruch et al.; data in panels C and D are from Weindruch and Walford.)

Data are from studies of 24-month-old male Sprague–Dawley rats either fed a control diet (80 percent of the average ad libitum intake) or subjected to caloric restriction (approximately 50 percent of the ad libitum intake) starting at 1 month of age. The numbers in parentheses are percentages of control values. The reduction in the weights of organs with caloric restriction varies widely. (Data kindly provided by Dr. Kevin Keenan, Merck, West Point, Pa.)

Reactive oxygen metabolites (ROMs) such as superoxide anion ( ), hydrogen peroxide (H₂O₂), and nitric oxide (NO·), are generated at several intracellular sites and either are inactivated by antioxidative defenses or give rise to a constellation of secondary ROMs. Interactions with ROMs may cause oxidative modifications in macromolecules, some of which may be repaired. The age-related accumulation of unrepaired, irreversible oxidative damage may be a causal factor in aging and certain diseases. ROMs have also been linked to differentiation and signal transduction. An X indicates the interdiction by nonenzymatic antioxidant defense mechanisms (e.g., glutathione [GSH], vitamin E, vitamin C, and urate). SOD denotes superoxide dismutase.

Data are for male C57BL/6NNia mice either fed ad libitum or subjected to a 40 percent reduction in caloric intake from four months of age. denotes superoxide anion, O₂ oxygen, and H₂O₂ hydrogen peroxide. The bars represent standard errors. Data were adapted from Sohal et al.