Free radicals are oxygen-containing molecules with at least one unpaired electron in their outer shell. This uneven number of electrons makes them “unstable” and causes them to react more easily with other molecules. Free radicals can trigger damaging chemical reactions in the body known as oxidation.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249911/
Free radicals are naturally generated by the body but exacerbated by certain chemicals, toxins, stress, illnesses, etc. While too much free radical damage can result in cell damage, a certain number of free radicals are natural and harmless. Free radicals can even fight off pathogens that cause disease. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3614697/ It is necessary, however, for a balance of free radicals and antioxidants to maintain proper physiological function.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249911/
The Free Radical Theory of Aging
The free radical theory of aging proposes that all aging (and diseases like cancer) result from cumulative oxidative damage to cells and tissues.https://pubmed.ncbi.nlm.nih.gov/16978905/
When free radicals outnumber antioxidants in the body, free radicals build up and trigger a cascade of cellular damage. This process can destroy healthy cells, including DNA, proteins, and lipids.https://pubmed.ncbi.nlm.nih.gov/8839918/
Reactive Oxygen Species vs. Free Radicals
Reactive oxygen species and free radicals are often referred to as the same thing, but a few differentiating factors exist.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4310837/
- Reactive oxygen species are a type of free radical.
- Reactive oxygen species are formed during cellular metabolic respiration and always involve oxygen, while not all free radicals involve oxygen.
- Free radicals are characterized by an uneven number of electrons, while not all reactive oxygen species have unpaired electrons.