If given the option, we would all like our bodies to stay in prime shape as long as possible. We’d prefer to still be able to move around freely, to retain our mental acuity, to keep our senses sharp and much more. The pipe dream of human beings conquering old age has been around since the dawn of human civilization; however, for most of our history, it was reserved for the realm of the divine and supernatural. Most recently, with the rise of aging research as a scientific field, we’re starting to see hope for turning this pipe dream into a tangible reality. As we begin to understand the biology behind our bodies’ slow but steady degradation, we are also gaining insights into potential therapies and treatments that may slow down, halt or someday even reverse the aging process. That being said, why wait for the development of these anti-aging treatments when we can improve our longevity right now by means of changing certain aspects of our lifestyle? In this article, we present you the science behind what is arguably the most important factor for slowing down the aging process, namely our diet, and how we can optimize it for extending our healthspan.
The mechanism underlying the aging process is rather complex, with many elements that interact with each other. It has been described in great detail in a 2013 paper published in the Cell journal, titled “The Hallmarks of Aging” [1], and the individual processes that contribute to aging described there are largely agreed upon by researchers in the field. There are 9 such hallmarks described. Some are relatively independent from the rest (e.g. loss of proteostasis, or in other words the increase over time of misfolded proteins or protein aggregates inside the cell), others being more interconnected (such as the decline of stem cell count and the accumulation of senescent cells). Anyway, our focus today will be on the hallmark epigenetic alterations, which underlies many other processes.
Epigenetics is commonly defined as the study of inheritable phenotype changes that are not related to changes in the DNA sequence, most often due to changes in gene expression. Consider the following question: if all the cells in our bodies carry almost exactly the same genetic information, how come a skin cell is so different from a liver cell or a neuron? Why can one do so many things the others cannot? It turns out that, although they all contain the same information, they use it in very different ways. Of the roughly 20,000 genes contained in the human genome, only a small fraction is “expressed” at any given point, meaning it gets transcribed into RNA and then translated into proteins. Therefore, it is this pattern of gene expression that dictates what each cell’s function is, whether it will undergo replication and so on. Not only is this expression pattern different across cell types, but the same cell can undergo changes in gene expression (i.e. epigenetic modifications) over time. The latter is generally dictated by internal regulation mechanisms as well as environmental factors, including our diets. It is such changes over time that contribute to the aging of our bodies [2]. Epigenetic modifications come primarily in the form of chemical alterations, either of the DNA itself (most commonly in the form of DNA methylation) or of the histones, the proteins that DNA is coiled around (which are usually acetylated or methylated).
It turns out that, regarding our diet’s impact on epigenetics and aging, it is not only what we eat, but also how much we eat that matters. One of the most well-studied diets in the context of aging research is caloric restriction (CR). The link between CR and extended lifespan has been empirically demonstrated across a wide range of animal models, and many of its health benefits are also found in human studies [3,4]. The reasons behind CR-induced deceleration of aging, though far from completely elucidated, have been shown to be at least in part related to epigenetics. A host of genes connected to aging-related processes such as telomere maintenance, cellular senescence, DNA repair and genome stability are all modulated by epigenetic modifications following CR diets [5,6,7].
As for the quality of our diet, although it is harder to separate fact from fiction, there are a handful of compounds whose geroprotective effects are backed by published data. The so-called “epigenetic diet” [8] contains food items rich in compounds or classes of compounds that promote the epigenetic maintenance of key anti-aging markers. To list a few: polyphenols are compounds naturally occurring in plants (e.g. curcumin found in turmeric, resveratrol found in grapes, EGCG found in green tea) involved in tumor suppression and prevention of metabolic changes associated with aging [9,10]; sulforaphane, a compound present in cruciferous vegetables (broccoli, kale, cabbage etc.) has been linked to anti-oxidant and anti-inflammatory effects and the prevention of neurodegenerative diseases [11]; spermidine, whose sources include aged cheese, mushrooms, soy products and others, owes its anti-aging effects to the promotion of autophagy (i.e. clearance of cellular debris) [12]. We should, of course, also include mentions of what to avoid in our diets: a recent study showed that alcohol has potential aging-accelerating effects by telomere shortening, which limits the number of divisions our cells can undergo [13].
The field of aging research is gaining rapid traction, and plenty of anti-aging treatments are already in clinical trials [14]. However, there is no way to tell how long these trials will take, or how many of them will successfully reach the market (if any). That is why, as of right now, lifestyle factors like diet, exercise, stress etc. are the best way to increase our odds of staying youthful for as long as possible, and we hope the guidelines above have provided you with a good place to start building more knowledge towards that goal.