The body's defence against free radicals
An antioxidant is a substance that slows or prevents the damage caused by free radicals. It works by donating an electron to a free radical, satisfying the radical's unpaired electron so that it becomes stable and stops attacking healthy molecules. Importantly, the antioxidant itself does not turn into a harmful radical after giving up an electron, so the chain reaction is broken.
Common antioxidants and their sources
| Antioxidant | Good sources |
| Vitamin C (ascorbic acid) | Guava, orange, chilli, leafy vegetables |
| Vitamin E (tocopherol) | Palm oil, nuts, seeds, vegetable oils |
| Beta-carotene (a form of vitamin A) | Carrot, pumpkin, papaya |
| Flavonoids | Green tea, cocoa, berries |
Malaysian red palm oil is naturally rich in both vitamin E and beta-carotene, which is why it has an orange colour. Different antioxidants dissolve in different places: vitamin C is water-soluble and works in the watery parts of the body, while vitamin E is fat-soluble and protects the fatty cell membranes. Because each type guards a different area, eating a wide variety of colourful fruits and vegetables gives better protection than relying on a single food.
Example
Eating a guava provides vitamin C. The vitamin C donates an electron to a free radical, neutralising it before it can damage a cell.
Why antioxidants matter
By mopping up excess free radicals, antioxidants help protect cells, slow down premature ageing and lower the risk of some chronic diseases. The best supply comes from a balanced diet rich in fresh fruits and vegetables. Very large doses from pills are not always better and can sometimes be harmful, so whole foods are preferred. Cooking vegetables gently, rather than boiling them for a long time, also helps to keep more of their vitamin C, since strong heat and long soaking can destroy this delicate antioxidant.
Key idea
Antioxidant + free radical → the antioxidant donates an electron, the radical becomes stable, and the cell is protected.