One longevity ring to rule them all (part IV): senescence

Over fifty years ago, a major discovery in microbiology was announced. Leonard Hayflick observed that cells divide about fifty times before the irrevocable cessation of that process: cellular sensescence. When a cell stops dividing, we call that a sensescent cell. This gave rise to the famous “Hayflick limit”, and it's intuitive that this is insurance against cancer gifted to us via our God of evolution.

However, the premium we pay for that accumulates as we age - the proliferation of senescent cells, which actively damage surrounding tissue and contribute to inflammation. The mechanism works broadly like this: once the Hayflick limit has been reached, senescent cells release the inflammatory senescence-associated secretory phenotype (SASP) chemical, to signal to our immune systems that they're ready for clearance. As we age, more of our cells retire AND our immune systems deteriorate; a double-whammy! If those cells are not cleared, then inflammation is the result. A prime example of this is the largest organ of the body for many individuals, body fat. We all know that obesity is a silent killer, yet hardly any of us non-specialists know the exact mechanisms. A prime goal of this series is to delineate on these, so hopefully you'll be more motivated to stay in shape. Indeed, preventing obesity is one of the best ways you can minimise the second derivative of age over time.

Compounds that clear sensescent cells are known as senolytics. One ubiquitous example is quercetin - concentrated in onions and apples. Admittedly the evidence as to whether consumption is pro-longevity is mixed, yet our priors should suggest some positive effect size. Another promising senolytic is fisetin. Those who indulge in strawberry picking as a hobby benefit.

The usual advice, to stay in shape and eat plenty of fruit and vegetables arises. Onions will be present in almost any dish worth cooking at home, so avoid ready-meals and cook yourself. Your taste buds will stand to benefit the most too! I may also pick up a new habit of eating strawberries, as in Britain, even the supermarket bought versions can be surprisingly tasty (counterintuitively, frozen is better on this metric).