Unfortunately, the majority of people today do not get the vitamins, minerals and antioxidants they need from their food. In a nutshell, junk food tastes nice and people will not be told to eat fruit and nuts. That is why many people informed about nutrition appreciate the vital importance of supplementing the modern diet with extra vitamins, minerals, antioxidants and other nutrients. The old idea that we can get all the nutrients we need from our diet, and that supplements just make expensive urine, is now widely recognized to be nonsense. People who say they don't need supplements because they are affluent and on a 'good diet' do not appreciate why they need antioxidants.
Antioxidants scavenge free radicals.
A major source of free radicals is the processed food of affluent society. Anti-oxidants are needed to counteract the damage done by the diet of affluent nations. There is now concern about safe doses of antioxidant supplements. Vitamins and minerals are good for us, but too much of anything can be harmful. Although there is no solid evidence that high doses of single antioxidant vitamins are really harmful, it is common sense not to take too much of any one on their own.