Aging Part 1: what causes us to age?

Mitochondria are tiny little energy factories found within every single one of our bodies’ cells. They are responsible for producing the overwhelming majority of ATP that sustains our biological processes throughout the day, for the entirety of our lives. ATP simply refers to the energy currency of biological systems, kind of like the Rand (or more appropriately the $ at this unstable time). The mitochondria do this by converting glucose (the main sugar produced from the breakdown of ALL carbohydrates) into carbon dioxide (this is where the CO2 that you must exhale all the time originates), water and of course ENERGY. Thus, they are completely invaluable to our survival.

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Mitochondria sit inside our cells, providing energy

As we’ve understood this complex metabolism in more detail, an interesting paradox has arisen. While they’re carrying out this life-giving process, they produce toxic by-products. These by-products are very reactive inside the cell, and cause damage to cellular components, especially DNA. DNA is the molecule which encodes your genome. Essentially, it is the blueprint which allowed YOU to be formed from a SINGLE cell. In addition, it contains ALL the necessary instructions required for your cells to function correctly, and gives rise to every single characteristic in your body. Thus, it is crucial that this DNA remains unchanged over time, as this information cannot be allowed to become distorted or lost.

Unfortunately, this is the very process that occurs. The damage from the toxic by-products causes changes in the sequence of DNA, leading to impaired cell function over time. This has diverse and far-reaching effects, as it is occurring in EVERY cell in your body, every second of every day. When we are young, we have mechanisms which can decrease this damage, and in some cases even REPAIR it entirely. For reasons that still remain poorly understood, this repair capacity is decreased as we age, allowing more and more mistakes to accumulate in our genome.

DNA damage occuring within your cells, caused by the toxic by-products of mitochondrial metabolism

DNA damage occuring within your cells, caused by the toxic by-products of mitochondrial metabolism

Once our cells gather sufficient damage, they cease to function properly, and eventually die off entirely. In non-regenerating structures like the brain and heart, they tend to be replaced by non-functional “scar-tissue”, which amongst other factors, leads to the physical manifestations of the aging process. In other tissues which can normally regenerate at high rates, like the skin, the quality of the proteins produced by these cells decreases dramatically. A notable is poor collagen formation and deposition, leading to sagging skin and loss of elasticity. Every system in the body tends to respond differently to this DNA damage, but the general consensus is astronomically decreased cellular function!

The theory outlined above has been grossly simplified, but the gist of it is that the very metabolism which keeps us alive, inadvertently degrades the quality of our cells, thus aging us. Independently, the protective and reparative mechanisms that normally mitigate this damage decrease with advancing age. The news isn’t all bad however, as tomorrow I will explore one of the most effective strategies for delaying the aging process currently known, which addresses this fundamental issue: caloric restriction.

– Kiril Trifonov [Hons(BSc) Physiology]

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