Oxidative stress is an imbalance between free radicals and antioxidants in your body. Free radicals are oxygen-containing molecules with an uneven number of electrons. The uneven number allows them to easily react with other molecules. Free radicals can cause large chain chemical reactions in your body because they react so easily with other molecules. These reactions are called oxidation. They can be beneficial or harmful.
Oxidation is a normal and necessary process that takes place in your body. Oxidative stress, on the other hand, occurs when there’s an imbalance between free radical activity and antioxidant activity. When functioning properly, free radicals can help fight off pathogens. Pathogens lead to infections.
When there are more free radicals present than can be kept in balance by antioxidants, the free radicals can start doing damage to fatty tissue, DNA, and proteins in your body. Proteins, lipids, and DNA make up a large part of your body, so that damage can lead to a vast number of diseases over time.
When the concentration of reactive species is not controlled by internal defense mechanisms such as antioxidants (tocopherols, ascorbic acid, and glutathione) or enzymes involved in oxygen radical scavenging (catalase, peroxidase, and superoxide dismutase, SOD), oxidative damage occurs to proteins, lipids, and DNA, which could lead to cytotoxicity, genotoxicity, and even carcinogenesis when damaged (mutated) cells can proliferate.