Understanding Antioxidants
To understand the role of antioxidants in physiology, one must first understand the definition of oxidation and free radicals. In scientific terms, oxidation is the loss of electrons. Oxidation can be seen in the rusting of metal and the browning of a slice of apple. This process serves both a positive and negative purpose in our bodies. In the positive sense, this oxidation/reduction (reduction is the gain of electrons) process allows our body to create energy and even fight bacteria. However, oxidation also causes the destruction of cell membranes and damages our DNA.
A free radical is a molecule with an unpaired electron. These molecules, such as a free hydroxyl group, are very unstable and desperately need to steal an additional electron. In fact, the half-life for such a molecule is approximately 10-8 sec-1 - that means in one second over 50 million radicals could have stolen an electron from your DNA, thus damaging it and you. Thus, by stealing electrons from other molecules in your body it causes them to undergo oxidation (lose electrons).
Free radicals cause molecules to undergo oxidation.
That's where antioxidants come in! They prevent the damaging effects of free radicals by donating an electron to the free radical to make it a stable molecule. This prevents the oxidation of your more important cell membrane, DNA, lipids etc. You may ask, well isn't the antioxidant, which lost an electron, now unstable? And does it then become a free radical?
Well you're catching on (see Nature's Antioxidants for your answer). To learn more about antioxidants, free radicals and our body choose from the following links.
More About Free Radicals and Oxidative Damage