Cup o'Joe-Can "Senolytics" Slow Aging?

Dietary supplement manufacturers have no problem putting the cart before the horse. In the usual scientific process, evidence is accumulated before recommendations are made based upon that evidence. When it comes to dietary supplements, it is not uncommon to make claims based on the flimsiest of evidence. This is the case for the so-called “senolytics,” molecules that in theory destroy senescent cells and thereby improve health and possibly reduce aging. “Senescence” is the process of growing old, unfortunately inherent to all life forms. The growth of the body, the healing of wounds, and constant regeneration of the skin, hair and fingernails all depend on the division of cells. New cells form and old ones die with their remnants being cleared away by the immune system. However, some cells eventually stop dividing but do not die. These are called senescent cells, and although they do not divide, they keep releasing chemicals that cause inflammation and also damage nearby healthy cells. As the years pass, the number of senescent cells increases, partly due to the failure of an aging immune system to clear them away. This has been connected to a number of age-related conditions including cancer, cardiovascular disease, osteoarthritis, decline in cognition and dementia. Even the “cytokine storm,” the release of inflammatory proteins called cytokines that are responsible for making COVID-19 so dangerous for older adults, has been linked with senescent cells. The possible removal of senescent cells has stimulated much research. Dr. Jim Kirkland of the Mayo clinic has been a pioneer in such research and has found that a combination of the chemotherapeutic drug dasatinib with quercetin, a polyphenol found in many fruits and vegetables, can destroy senescent cells in mice. Such substances that destroy senescent cells are termed “senolytics.” When middle-aged mice are treated with dasatinib and quercetin, the onset of age-related ailments is delayed, and even older mice apparently benefit from such treatment, becoming stronger and spryer than their untreated peers. Fisetin, another polyphenol found in plants, has also been shown to destroy senescent cells in laboratory studies. All of this is very interesting, but as scientists are fond of saying, the body is not a large Petri dish, and we are not giant mice. There are no published clinical human trials that have documented the benefits of senolytics for the general population. Even if there is a benefit, the question of dosage has to be resolved. Furthermore, there is no clear evidence that senolytics do not affect healthy cells, a possibility depending on the dose. Such unknowns have not stopped supplement producers from promoting various senolytics as “groundbreaking” and as a “potential fountain of youth.” Senolytics may with time turn out to really be age-reducing substances, but that time has not yet come. In the meantime, let’s keep emphasizing the health benefits of fruits and vegetables, for which there is ample evidence. Indeed, it may well be that these benefits are linked to their content of senolytics.