Antioxidants are substances that have the capability of countering and neutralizing free radicals, rendering them harmless. If you look at the electrical imbalance on a free radical as a short, sharp blade that it uses to hack and slice off bits of the cell that it impales on the blade, then you might look at an antioxidant as being a cork. This cork is of such a nature that it seeks out free radicals and presses itself onto the free radical's knife blade. This covers the sharp blade and prevents it from slicing and hacking any further.

We saw earlier that we can never be entirely free of free radicals. They are an integral part of our physiology, an end product of the biochemical reactions involved in our energy production. If we do physical exercise, we generate energy, but we also generate free radicals. If we increase the exercise, besides the increased benefits we obtain, we also generate still more free radicals. However, we need a certain amount of exercise, so the answer is not to become sedentary and immobilized.

In addition to generating free radicals through our normal physiological processes, the modern world induces a higher level of free radicals in many of us indirectly, through the pollution and smog in the environment, through the action of the sun's radiation on our skin, through unhealthy diets, through cigarette smoke, stress, and even lack of exercise, cancer may be the result.