What does antioxidant mean?
An antioxidant is a substance that inhibits oxidation, a chemical process in which molecules lose electrons and can form damaging free radicals. The word has two principal applications. In industry, antioxidants are added to foods, oils, plastics, rubber, and fuels to slow spoilage and degradation caused by exposure to air. In biology and nutrition, antioxidants such as vitamins C and E neutralize reactive oxygen species produced during normal metabolism, helping to protect cells from oxidative stress. The term entered English in the early twentieth century, formed from the prefix 'anti-' combined with 'oxidant', and its rise closely tracked scientists' growing understanding of oxidation chemistry. Today 'antioxidant' is most familiar to the public through health discourse: fruits, vegetables, tea, and wine are routinely praised for their antioxidant content. While the underlying chemistry is well established, popular claims about antioxidants preventing disease often outrun the scientific evidence, so the word carries both genuine scientific weight and a degree of marketing hype.
nounA substance that inhibits oxidation, especially one used to counteract the deterioration of stored food products, or a substance (such as vitamin C or vitamin E) that removes potentially damaging oxidizing agents in a living organism.
- A substance that inhibits oxidation or reactions promoted by oxygen, especially one added to food, fuels, plastics, or other materials to prevent spoilage or degradation.
- A substance in living organisms, such as vitamins C and E, that neutralizes reactive free radicals and protects cells from oxidative damage.
"Berries are rich in antioxidants, which help protect the body's cells from oxidative damage."
"Manufacturers add antioxidants to vegetable oil to keep it from going rancid."
"Nutritionists often recommend eating colorful fruits and vegetables because they are naturally high in antioxidants."
The plural is standard and commonly used when referring to multiple antioxidant compounds or antioxidant-rich foods collectively.
"Green tea and dark chocolate both contain several different antioxidants."
The word 'antioxidant' didn't exist until the 20th century — it was coined only after scientists figured out what oxygen's dark side actually was.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of antioxidant
The word 'antioxidant' is a modern scientific formation of the early twentieth century, built from the prefix 'anti-' (from Greek 'anti', meaning 'against') joined to 'oxidant'. Its component parts trace back further: 'oxidant' derives from 'oxide' and ultimately from Greek 'oxys', meaning sharp or acid, the same root that gave English 'oxygen' and even 'oxymoron'. The term emerged once chemists understood oxidation well enough to name substances that counteract it.
How antioxidant is actually used
Antioxidant is almost always used as a noun, though it occasionally functions attributively (e.g., 'an antioxidant-rich diet'). The term carries strongly positive connotations in health and nutrition contexts, where it is frequently used in marketing language — sometimes more loosely than laboratory science would strictly justify.
Easily confused with antioxidant
An oxidant is a substance that causes oxidation by accepting electrons, whereas an antioxidant does the opposite — it inhibits or slows oxidation.