What are food supplements for?

A healthy diet is supposed to supply to people the components of recommended daily allowance. However, the majority of people are far from achieving it. Not only food from modern agriculture is becoming impoverished in specific nutriments, but it also contains pesticides and chemical fertilizers, which increase considerably the oxidative stress to our cells. Food supplements help alleviating some deficiency or responding to specific needs (sports activity or some cases that required higher amounts of nutrients than normal).