What are antioxidants and how do they keep us healthy?

Reactions of biochemicals underly all the functions of our body.  How we turn food into energy, the function of our brains and other organs, the movement of our muscles, these all require the reactions of biochemicals inside and outside the cells of our body.  A natural consequence of these reactions is the generation of free radicals, highly reactive intermediates of some of these biochemical reactions.  Due to their high reactivity free radicals can initiate damaging oxidizing reactions, just like metal is damaged by oxidation to become rusty.  The damaging reactions promoted by free radicals are generally termed oxidative stress.  Oxidative stress has been implicated in many diseases including diabetes, cancer, atherosclerosis, heart disease and asthma.


Our lifestyle can contribute to the levels of oxidative stress our bodies are exposed to.  For example cigarette smoke and some components of the food we eat can cause the generation of free radicals.  Also by exercising levels of oxidative stress are elevated as a result of the higher levels of free radicals generated by the cellular reactions that are required to increase energy mobilization and muscular activity during exercise. While the major source of oxidative stress in our bodies is from biochemical reactions within our body, the environment we are exposed to, for example sunlight and pollution, can also contribute to increased levels of oxidative stress.


Fortunately our bodies are well equipped to deactivate free radicals and manage oxidative stress.  We have an arsenal of endogenous compounds in our bodies that mop up or scavenge and deactivate free radicals reducing the level of oxidative stress that our bodies are exposed to.  These are generally referred to as antioxidants and include compounds like Vitamins C and E, glutathione and enzymes like superoxide dismutase and glutathione peroxidase.  The maintenance of adequate levels of endogenous antioxidants is very important to minimise the level of oxidative stress that our bodies are exposed to, helping us maintain good health.


We can compromise our endogenous antioxidant capacity if we have a diet deficient in certain nutrients, expose ourselves to high levels of environmental stress factors, or overstress our bodies with exercise as an example.  One of the health food messages we are bombarded with is based on us being encouraged to eat or supplement our diet with antioxidants.  While there is little evidence that the antioxidant compounds in these foods or supplements directly add to the body’s antioxidant capacity exciting new research is showing that some of these antioxidants can actually activate the body’s own endogenous antioxidant arsenal and decrease oxidative stress levels.  The antioxidants in New Zealand blackcurrant are examples of compounds that are very good at activating the body’s own oxidative stress management system minimising the adverse effects of environmental and exercise stress.

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