| Popis: |
In various animal models, caloric restriction is the most effective and reproducible intervention to extend life span and to reduce risks of aging-related chronic diseases, particularly cancer. Findings from human studies based on ecologic comparisons, the Norwegian famine during World War II, and patients with anorexia nervosa suggest that caloric restriction reduces cancer risk, especially the risk of breast cancer. In contrast, transient and abrupt caloric restriction with malnutrition followed by compensatory overnutrition may counter any protection conferred. Several earlier hypotheses for the biological mechanisms underlying the association between caloric restriction and longer life span and decreased cancer risk such as retarded growth and development, reduced metabolism rate, endocrinological changes, and decreased accumulation of oxidative damage were refuted by laboratory results. More recent findings suggest a hormesis hypothesis proposing that caloric restriction conveys a low-intensity biological stress on organisms, which may elicit an adaptive response of enhanced maintenance and repair. The identification of a new class of caloric restriction mimetic molecules that target the SIR2 family of longevity-promoting enzymes may provide a novel intervention for the prevention and treatment of cancer and other aging-related chronic diseases. Epigenetic mechanisms may also play a role. |
