Antioxidants
Molecules that neutralise free radicals and protect cells from oxidative stress, including vitamins (C, E), minerals (selenium, zinc) and phytonutrients (polyphenols, carotenoids).
Antioxidants fight free radicals: unstable molecules produced by normal metabolism, pollution, tobacco, UV and stress. In excess, these radicals cause “oxidative stress”, damaging DNA, proteins and fats and speeding up ageing and disease.
A fresh angle (the supplement paradox): counter-intuitively, taking antioxidants in mega-doses does not improve health, and may harm it. Several large clinical trials (beta-carotene, high-dose vitamin E) showed an increase in the risk of certain cancers or in mortality.
Why? Oxidative stress is not always bad: it is a useful cell signal (hormesis). For example, the free radicals produced during exercise trigger beneficial adaptations (in muscle and mitochondria). Taking antioxidants straight after training can block these adaptations.
The modern conclusion: antioxidants are beneficial when they come from whole foods (where they work in synergy and at moderate doses), not from concentrated supplements. A colourful plate (berries, green vegetables, spices) beats any pill.
A related key concept is ORAC (Oxygen Radical Absorbance Capacity), which measures a food’s antioxidant power. Its relevance in the body is debated, however, because it does not predict the real effect after digestion.