Ageing is the result of a combination of genetic and environmental factors: DNA shortening, oxidative stress, glycation... Here we take a look at the ageing process, its causes, and the ways in which we can slow it down.
Ageing is a natural process – the body is genetically programmed to age. There is a finite number of times that our cells can divide and replicate. Each time they do so, the telomeres of our chromosomes get shorter – these are the protective tips at the end of each strand of DNA.
There is a limit to a cell’s ability to cope with this shortening, beyond which cellular DNA ceases to replicate, and along with it, the cell. Once this critical length is reached, the process of cell death is triggered. The cell undergoes a morphological change, mobilising the immune system, which ensures the cell is eliminated. Cell death leads more broadly to tissue death, and the body suffers progressive damage. This is part of the body’s natural cycle, but there are other mechanisms which account for premature ageing.
Oxidative stress is often highlighted as a damaging process for the body, but what is the mechanism behind it?
The process of oxidation which takes place in cells results in the formation of unstable molecules that contain unpaired electrons. These molecules, called free radicals, try to restore their stability by stealing an electron from another molecule. This triggers a rapid chain reaction, which the body is not always equipped to deal with.
The body has a range of natural antioxidant compounds at its disposal which are able to neutralise these free radicals. They include glutathione, enzymes (peroxidase, catalase, superoxide dismutase...), and vitamins C and E... But when these antioxidant reserves are inadequate, free radical attacks turn into oxidative stress. Along with the accompanying chain reaction, oxidative stress leads to the denaturation of proteins, lipids, and indeed all the molecules that form the body and make it function. Organs, skin, the nervous and cardiovascular systems, the whole body is affected by oxidative stress, and the result is premature ageing.
While oxidation occurs naturally in the body, a number of external factors are known to exacerbate oxidative stress. They include smoking, alcohol, a diet low in fruit and vegetables, pollution, UV rays, and stress...
The process of glycation is of increasing interest to researchers investigating ageing. It is a mechanism whereby sugars bind to proteins, creating glycated proteins.
It occurs at a greater rate when the body is overloaded with sugar, which is why it is seen more in diabetics. Glycated proteins ultimately produce what are called advanced glycation end-products or AGE: these play a role in premature ageing. They cause structural changes, particularly in cutaneous tissues, resulting in a slackening of the skin.
They also damage blood vessel walls, muscle cells and white blood cells... In short, the whole body is affected by excessive glycation. What’s more, AGE are not broken down by the body. Eliminating them is left to the kidneys but they cannot cope with excessive glycation and this leads to the accumulation of harmful residues. It’s another cascade of reactions that promotes premature ageing.
We’re all familiar with the consequences of ageing. They can be visible: deep lines and wrinkles, a bent spine, grey hair... and they can also be less obvious but pathological: cancer, neurodegenerative disorders and cardiovascular disease...
In order to slow down the ageing process, it naturally makes sense to adopt a sensible lifestyle. Eating a balanced diet high in antioxidants, taking regular exercise, and ensuring you get good quality sleep will all help to reduce oxidative stress and excessive glycation. It is also highly advisable to reduce alcohol consumption and refrain from smoking.
You can go further by taking compounds called senolytics. These molecules are currently being studied by scientists keen to learn more about their ability to slow down cellular ageing. Some of these natural compounds are already well-known: