BackgroundNutrition plays a significant role in the human life cycle because it provides energy, helps prevent disease, and promotes growth. The first documented evidence linking dietary restriction and aging dates back to 1935 in a study conducted by McCay et al who found that reducing the amount of calories consumed by 20% without causing malnutrition increased lifespan and resistance to age-related diseases in a rodent model (Colman et al., 2009; Typically, several authors suggest that a 10-40% reduction in calorie intake is effective in extending life, although a recent study using a 30% dietary restriction % was found to be ineffective in doing so in rhesus monkeys (Mattison et al., 2012). Several hypotheses exist to explain the mechanism underlying life extension due to caloric restriction (CR). Some early theories that never gained much support include the following: McCay's original hypothesis that CR reduced the rate of growth and development and therefore increased lifespan; CR reduced metabolic rate resulting in slower aging; and that the control animals used in the experiments eat much more than normal, which causes them to age more rapidly than CR animals (Sinclair, 2005). CR at any stage of life has since been found to extend lifespan, and animals with CR show similar or greater metabolic rates than control animals, and life extension due to CR is significant even when Study controls are fed a normal food (not ad libitum diet) (Sinclair, 2005). Another study proposed that CR slowed the aging process by increasing resistance to hyperoxidation. As aging progressed in yeast and other animals, the presence of free radicals increased in the cells. Usually, the levels of...... middle of paper ......52.x.Molin, M., Yang, J., Hanzen, S., Toledano, M., Labarre, J. and Nystrom, T. (2011). Lifespan extension and H2O2 resistance induced by caloric restriction require peroxiredoxin Tsa1 in Saccharomyces cerevisiae. Mol Cell, 43(5): 823-833. doi:10.1016/j.molcel.2011.07.027.Ooka, H., Segall, P. & Timiras, P. (1988). Histology and survival in late-life rats fed low tryptophan. Aging Mech Development, 43(1): 79-98. doi:10.1016/0047-6374(88)90099-1.Sinclair, D. (2005). Toward a unified theory of calorie restriction and longevity regulation. Mech Aging Dev, 126(9): 987-1002. doi:10.1016/j.mad.2005.03.019.Trepanowski, J., Canale, R., Marshall, K., Kabir, M., & Bloomer, R. (2011). Impact of calorie and dietary restriction regimes on markers of health and longevity in humans and animals: a summary of available findings. Nutr J, 10: 107. doi:10.1186/1475-2891-10-107.