As I've mentioned in the past, autophagy - the process by which cells destroy and replace damaged or old components - seems to be very important in the natural longevity you are granted by the operation of your metabolism. It's required for the longevity boost given by calorie restriction, for example. Some groups would go so far as to say that most or all longevity-inducing tweaks to metabolism operate through increased autophagy: "Autophagy is involved in cellular protein and organelle degradation, which is mediated by the lysosomal pathway. [Autophagy] has a key role in cellular housekeeping by removing damaged organelles. During aging, the efficiency of autophagic degradation declines and intracellular waste products accumulate. In Caenorhabditis elegans, there is clear evidence that lifespan is linked to the capacity to regulate autophagy. Recent studies have revealed that the same signaling factors regulate both aging and autophagocytosis, thus highlighting the role of autophagy in the regulation of aging and age-related degenerative diseases. Here, we examine in detail the interactions of the signaling network involving longevity factors SIRT1, mTOR, FoxO3, NF-kappaB and p53 in the regulation of autophagy. We discuss the possibility that these well-known stress resistance and longevity factors regulate the aging process via autophagy."

Link: http://www.ncbi.nlm.nih.gov/pubmed/19380253