2020 / 10 / 25
Ageing is an inevitable physiologic phenomenon for human beings. However, this phenomenon manifests itself uniquely in every individual. Furthermore, ageing may be the biggest challenge every one of us should face during her/his lifetime.
The common changes associated with ageing are similar in all of us. In general, we have an increasing proportion of body fat versus bone and muscle. This can affect health in many ways. For instance, older people sometimes lose balance and equilibrium, strength, and mobility, which can trigger a vicious cycle of morbidity. Metabolic rate begins to decrease, and weight begins to increase, initiating other changes, such as cardiovascular diseases, diabetes, and possibly increases the risk for developing cancer.
However, these do not have to be invariable accompaniments to ageing. In fact, for all of us ageing in our time has markedly improved from the era of our grandparents and great-grandparents.
Probably about a third of the ageing process is determined by our genes (nature) and almost twice as much is determined by our environment (nurture), which we can control to a great extent.
With our fast-paced lifestyles, we have access to shortcuts, such as fast foods, that support our faster pace but are detrimental to our health. We get inadequate , and we may consume and get addicted to beverages and substances that can artificially upregulate our already fast pace such as all the caffeine and nicotine derivatives. Yet, despite all these gloomy facts, many of us are living longer and healthier lives because, with increased awareness, we can choose better lifestyles, that can eventually lead to better overall health and well-being.
The truth is that we can bypass illnesses and frailties that many in the medical community have come to accept as part of “normal ageing,” such as diabetes, cardiovascular disease, and to some extent cancer. Many of these diseases can be prevented, slowed down,´-or-even reversed to a certain degree. What is required of us is that we listen to our bodies and respond with healthy lifestyle choices.
To understand how we age well, we need to understand the biologic process of ageing. Human cells cannot live for ever, and they have to reproduce themselves when they get old´-or-injured. Broadly speaking, human cells have about 30 to 50 divisions before they lose ability to reproduce. This maximum number of divisions is called the Hayflick-limit-. Our individual cells replicate based on need. Red blood cells, for example, turn over completely in 120 days, while bone cells take years. Adult stem cells can replace many of these lost cells that no longer can replicate. But when a larger number of cells reach their replication-limit-, the adult stem cells tend to be incapable of restoring every single cell that cannot replicate any more. At this stage ageing starts, which will be augmented when the available number of stem cells stored since birth in each organ of the body dwindles and starts to be depleted. Human tissues cannot produce new stem cells other than the ones produced during the foetal development and stored since birth in certain numbers in each specialised organ of the body.
The most important-limit- on our cellularity probably comes from telomeres. The telomeres are the end bodies of our chromosomes. They act like a cap at the end of each chromosome, which is responsible for maintaining the structural integrity of each individual chromosome. At every replication, a little bit of the telomere is lost-;- eventually, all the telomere is lost, and replication is impossible because the integrity of the chromosome is gone.
There is an enzyme called telomerase that repairs those ends, but normal cells do not have it, while all cancerous calls do have it abundantly. This enzyme is behind the defining characteristic of cancerous cells that they can divide forever. Some people have suggested introducing telomerase into normal cells as a way to increase longevity, but such tinkering might encourage normal cell to mutate into cancerous cells. Therefore, we need to find other roads to life extension. Apparently, the easiest of these roads are the healthy lifestyle choices we can pursue to delay ageing and ameliorate its effects on the quality of our lives.