Dietary Restriction, Hormesis, and Small Molecule Mimetics

Publisher Summary This chapter summarizes some of the key discoveries in dietary restriction (DR) research and explains the dramatic physiological effects and health benefits of DR. A team of researchers at the Cornell University studied that if the pace of development of an animal were slowed by restricting food intake, its life span would correspondingly increase. They tested this idea by substituting 10 to 20 percent of the rats' diet with indigestible cellulose, thus cutting back on their caloric intake. Consistent with predictions, the underfed rats did develop slower and lived substantially longer, although the hypothesis was ultimately proven incorrect. Another group of researchers tested the effects of diet composition and implementing DR at different ages and at more moderate levels of restriction. They found that a 30 percent reduction in the caloric intake was close to optimal in rats, with a doubling of life expectancy and an increase in maximum life span of more than 30 percent. The hormesis hypothesis of DR attempts to unite various theories on the proximate causes of aging. In a similar way, the xenohormesis hypothesis suggests that many of the health benefits of dietary phytochemicals, particularly those of secondary metabolites produced by plants under stress, may work because they activate an evolutionarily ancient mechanism that allows animals and fungi to pick up on chemical stress signals from plants.