Antioxidants get a lot of hype. Foods that are naturally high in antioxidants get called super, antioxidant supplements are sold as a cure-all, and they’re even added to processed foods to bump their health credentials. So what are they, and what do they do?

Free radical fighters
Antioxidant is an umbrella term for compounds that can prevent oxidation and neutralise free radicals. Free radicals are reactive molecules that damage cells. They also cause chain reactions, making more free radicals as they go.

Even the healthiest people produce free radicals. Normal levels are easily tolerated, but bad habits such as smoking, drinking and a poor diet increase our exposure. These additional free radicals may increase the risk of lifestyle- and age-related diseases such as cancer and cardiovascular disease. Sometimes, though, free radicals are helpful, for example when our immune cells use them to kill and digest bacteria and viruses.

Antioxidants stop the free radical chain reaction. This has led to the idea that large amounts of antioxidants might help stop the free radical damage that leads to chronic diseases and ageing. Unfortunately, as is often in the case in nutrition, the message has become overly simplified, and a bit twisted.

Not all antioxidants are created equal
Hundreds of substances can act as antioxidants. Vitamin E, vitamin C, beta-carotene, lycopene and polyphenolics are a few well-known examples found in foods. Each antioxidant has different properties, so variety is the key rather than huge serves of any one in particular.

Supplements aren’t foods
Antioxidants in supplements probably don’t act the same way as those found in foods. There are lots of studies linking diets high in antioxidant-rich foods to good health, but fewer linking supplements to the same outcomes. This is probably because foods high in antioxidants, such as fruits and vegetables, are also high in fibre and other nutrients, and displace less healthy foods in our diets.

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More isn’t necessarily better
In high concentrations, antioxidants can act as pro-oxidants, and actually produce free radicals. A large study investigating whether antioxidant supplements could reduce risk for cancer had to be stopped early because the participants receiving the supplements were actually getting more cancers.

We also make antioxidants – such as glutathione and coenzyme Q10 – naturally in our own bodies, and taking too many extra antioxidants could compromise their production and function.

Don’t put all your eggs in the antioxidant basket
The hype around antioxidants can give us a false sense of security, but antioxidants aren’t a free radical free pass. Instead of looking for megadoses in supplements and “superfoods”, you’d be better off avoiding the bad habits that increase our free radical load. No matter how hard we try, it’s wishful thinking to believe the antioxidants in chocolate and wine cancel out the sugar, fat and alcohol and make them “health foods”.

You don’t need to spend big on supplements and “superfoods” to get enough antioxidants. The best thing you can do is keep eating between five and eight servings of fruit or vegetables every day, and avoid unnecessary, expensive and potentially harmful supplementation.

Dr Emma Beckett is Broadsheet’s nutrition columnist. A molecular nutritionist with a Ph.D. in Food Science, she is a post-doctoral fellow in the School of Medicine and Public Health and the University of Newcastle. In a world of mixed messages she can be found busting nutrition myths and empowering people to critically assess nutrition information. She tweets at @synapse101.