Oxidative stress refers to the unwanted reactions between reactive oxygen species and components of cells. These can damage proteins, lipids, and DNA. However, this also makes them beneficial in the defence against pathogens and consequently they are used by the immune system to combat infections.
Oxidative stress occurs when the production of oxidising species overpowers the ability of antioxidant defences within the body. Reactive oxygen species are important for cell signalling and thus it would be premature to label them as 'bad'. The key is to strike a balance between oxidising species and their respective antioxidants.
Antioxidants are molecules that prevent the oxidation of other molecules. Antioxidant defences maintain oxidant concentrations within an optimum range as opposed to removing them entirely.The jury is still out on antioxidant supplementation however, as studies have so far presented positive findings, negative findings, and no change with regards to the illnesses that are attempted to be treated or prevented.
Oxidation occurs occurs when a substance loses an electron or hydrogen to an oxidising agent. Reactive oxygen species are produced by oxygen, which is a highly reactive molecule.