The most widely accepted theory for why we age is the Free Radical Theory of Aging, or as it is better known today – The Mitochondrial Theory of Aging. This theory essentially states that the reason we age is due the amount of free radicals we are exposed to, and there is a convincing amount of evidence to support this theory. Before we go into the details of this theory, you need to understand what is happening inside our cells when we age.
At the end of all of our genes is a sequence of DNA which doesn’t code for anything in the body. At college level biology, this was sometimes referred to as ‘junk’ DNA, but it does have a purpose. These bits of ‘junk’ DNA are called telomeres and their job is to protect DNA from damage and unravelling. They themselves get damaged, and can even be repaired by specialised enzymes, but the damage to telomeres has no effect our genes function – which is good for us. However, as our cells replicate and divide, these telomeres become shorter and shorter. This reduces the amount of protection the DNA has, thus, increasing the damage it will sustain.
So, as we age our cells divide/ replicate more, which makes our telomeres shorter, which makes our DNA more vulnerable to oxidative damage.
There are numerous sources of radical damage – diet, pollution, sun, and even exercise, but the biggest source of radical damage is ourselves. When our cells produce energy, they create a very reactive radical called superoxide. We produce lots of it, and our body is well equipped to neutralise it with specialised enzymes, but it cannot all be mopped up, and some damage is inevitable.
As our body ages and our telomeres shorten, our body is less well equipped to repair/ protect our genes from super-oxide, and so our genes can get damaged. This leads to the development of the typical signs of aging – stiff joints, reduced mental agility, cancerous cells and wrinkly skin – all of which are know to be caused prematurely by high exposure to sources of radicals, such as regular use of sun beds, or long-term smoking.
Just think, have you ever seen someone who has spent too many hour on a sun bed/ regularly smokes who has more wrinkles than they should at their age? That’s radical damage for you.
The radical damage from superoxide and other radicals can be minimised with a good diet high in antioxidants and precautionary measures such as not smoking. This can limit, or even delay the development of the signs of aging. But as our main source of radical damage is our own cells, both from the shortening telomeres, and production of superoxide, aging is sadly inevitable.
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We age because our ability to protect ourselves against radical damage diminishes over time. This leads to more radical damage to our genetics.