Caloric Restriction Slows Down the Ageing Process
McCay et al first provided evidence in 1935 to suggest that caloric restriction slows down the ageing process and that it could potentially increase life span. Research has since expanded and yielded exciting results in many organisms which back up this concept. Bodkin et al (1995) enforced long term caloric restriction on adult male rhesus monkeys. The research group noted that the mortality rate in the control groups was higher than in the dietary restricted group. It can be seen that caloric restriction leads to changes in physiological changes that have the eventual effect of increasing longevity. (Guarente, 2005)
Guarente et al (2001) have been exploring ageing in Saccharomyces cerevisiae. They noted that the sir-2 gene in yeast causes increases longevity in addition to silencing sections of the yeast genome. The sir-2 gene is known as the silent information regulator-2 and it is a NAD histone deacetylase (Nicole, 2007).The research group also noted that under dietary restriction sir-2 is activated through accumulation of NAD and thus leads to increased longevity. The research group assumed this was due to the fact that sir-2 inhibits proteins that affect the daf-16 protein.
The human homologue of the sir-2 gene is sirt1 (Royle, 2007). Guarente et al (2005) proposed that when there is caloric deficiency, the sirt1 gene detects this change and alters various biological and physiological processes which lead to increased lifespan.
One hypothesis as to why we see changes in health and longevity during a caloric restriction is because it causes reduced metabolic activity and this in turn decreases the amount of protein and lipid damaged through the harmful by-products of these metabolic pathways (Heilbronn et al, 2003).
