Nutrition briefing
Antioxidants
Antioxidants are substances in food that the body uses as protection against free radicals: unstable molecules produced during normal metabolism that can do real damage if they build up through illness, ageing, or overexposure to toxins or the sun.
How free radicals cause damage
They oxidise nearby molecules
Free radicals are highly unstable and react quickly with whatever is closest, setting off a chain reaction called oxidation. Left unchecked, this has harmful effects throughout the body.
They can damage DNA
If free radicals oxidise DNA, the reaction can trigger cell mutations, which may be one of the first steps toward cancer.
They oxidise cholesterol
Oxidation of cholesterol particles in the blood can trigger fatty deposits in the arteries, which may lead to heart disease or stroke.
They accelerate wear and tear
Free radicals have also been linked with cataracts, immune deficiency, arthritis, and premature ageing.
The role of antioxidants
The body produces its own antioxidants, which neutralise the effects of free radicals to a certain extent. But the vitamins, minerals, and plant compounds known as phytochemicals provide an extra supply. Additional dietary sources are essential for maintaining good health, which is why a steady intake of the foods below matters.
The key antioxidant nutrients
Each of these plays a distinct protective role. Aim to draw from a wide spread of food sources rather than leaning on any single one.
| Antioxidant | Antioxidant effect | Food sources |
|---|---|---|
| Vitamin A (retinol or carotenoids) | Diets high in carotenoids are linked with a reduced risk of some cancers. | Retinol: animal foods, oily fish, eggs, butter. Carotenoids: brightly coloured plant foods such as carrots, dark green leafy vegetables, sweet red peppers, and pumpkin. |
| Vitamin C | Hunts for free radicals and regenerates the antioxidant potential of vitamin E after it has reacted with free radicals. | Citrus fruit, kiwi fruit, blackcurrants, strawberries, potatoes, green and red peppers, tomatoes, bean sprouts, and green leafy vegetables. |
| Vitamin E | Helps prevent oxidation of polyunsaturated fatty acids in cell membranes. The more polyunsaturated fat you eat, the more vitamin E you need to protect it from oxidation. | Nut oils, almonds, hazelnuts, sunflower seeds, tuna, salmon, avocados. |
| Copper | Present in many enzymes that protect against free radical damage. Required for healthy bone growth, connective tissue formation, and to aid iron absorption from food. | Shellfish, liver, nuts, mushrooms, wholegrain cereals. |
| Manganese | Present in enzymes that protect against free radical damage. | Nuts, brown rice, wholegrain cereals, beans, lentils. |
| Selenium | Present in the enzyme that protects DNA against free radical damage. Deficiency increases the risk of prostate cancer. | Brazil nuts, seafood, seaweed, avocados, whole grains, sunflower seeds. |
| Zinc | Present in enzymes that protect against free radical damage. | Shellfish, lean meat, poultry, eggs, pumpkin seeds, sunflower seeds, nuts, whole grains. |
Frequently asked questions
What are antioxidants and what do they do?
Antioxidants are nutrients that neutralise free radicals, the unstable molecules produced during normal metabolism that can damage DNA, oxidise cholesterol and contribute to wear and tear in the body. The seven core dietary antioxidant nutrients are vitamins A, C and E, plus the minerals copper, manganese, selenium and zinc. The body makes some of its own antioxidants, but dietary sources are essential to keep the supply topped up.
What foods are high in antioxidants?
Antioxidant-rich foods are largely colourful plant foods. Good sources include brightly coloured vegetables and fruit, oily fish, nuts, seeds, herbs, spices and cacao. The simplest strategy is to eat a varied, brightly coloured, plant-rich diet so you cover the range of antioxidant nutrients, since different colours tend to signal different protective compounds. This variety helps the body counter oxidative damage across many tissues.
Why does the body need dietary antioxidants?
Although the body produces some antioxidants itself, dietary intake is needed to maintain an adequate supply against the constant production of free radicals. Each of the seven core antioxidant nutrients plays a role, for example vitamin E protects the polyunsaturated fats in cell membranes, while adequate selenium and carotenoid intake have been linked with lower disease risk in research. A varied, colourful diet is the practical way to keep these protections in place.
Reviewed by Rohan Smith, BHSc Nutritional Medicine · Elemental Health & Nutrition, Adelaide. Last reviewed 13 June 2026.
Important: This summary is general information, not personalised medical advice, diagnosis, or a treatment protocol. Speak with a qualified practitioner about your individual situation. Book a consultation →