Mechanism is not the same as benefit
Antioxidants reliably neutralize free radicals in a test tube, but that doesn't translate into broad disease protection in people. NCCIH summarizes that antioxidant supplements have not been shown to reduce the risk of major chronic diseases, and that some high-dose antioxidants were associated with harm in trials [1].
Why food beats high-dose pills
Whole foods deliver antioxidants in balanced, modest amounts alongside fiber and other compounds — the form linked in research to health benefits. Isolated high-dose supplements can disrupt the body's own redox balance; for example, very high vitamin E intake has its own risks [3], and megadosing vitamin C offers no added benefit beyond adequacy [2].
Where specific antioxidants have a role
- Vitamin C and E matter for meeting needs, not for megadosing [2][3].
- Astaxanthin, quercetin, resveratrol, sulforaphane, and alpha-lipoic acid have interesting but mostly preliminary human data for specific uses.
- NAC is used in specific clinical settings and interacts with some medications — not a casual antioxidant.
A note for athletes
High-dose antioxidants taken around training may blunt some of the beneficial adaptations exercise produces, so loading up to 'aid recovery' can be counterproductive.
Practical guidance
Get antioxidants primarily from a colorful, plant-rich diet; use vitamin C and E to meet needs rather than megadose; treat specialty antioxidants as situational experiments with realistic expectations; and avoid high-dose antioxidant stacking, especially around exercise [1][4].
