As such, the society promotes an individualized, evidence-based approach, recognizing that small to moderate exercise-induced oxidative stress aids adaptation, while excess oxidative stress causes harm.
“Antioxidants play a complex, context-dependent role in vivo; they can facilitate recovery from exercise but may also hinder training adaptations when consumed at supraphysiological doses,” the researchers wrote in the Journal of the International Society of Sports Nutrition. “While endogenous antioxidant systems can effectively maintain redox balance, dietary sources, particularly whole foods, can help mitigate excessive oxidative stress following intense/heavy training or inadequate recovery.”
Conclusions were established based on a comprehensive review and critical analysis of the literature on antioxidants conducted by a team of leading human performance and exercise science experts in the field to inform athletes, dietitians, trainers and other practitioners about the contextual complexities of antioxidants.
Striking a balance between recovery and blunting
The position stand highlighted the need to strike a delicate balance between supporting recovery and potentially blunting physiological adaptations (e.g. with high-dose supplementation).
Factors influencing individual’s response to dietary antioxidant supplementation include training status, baseline endogenous antioxidant capacity and oxidative stress levels, sex and gender differences, age-related changes in redox homeostasis, overall nutritional status and habitual dietary antioxidant intake, the type, dosage and timing of antioxidant administration, the chemical form and bioavailability of the antioxidant compound, the type, intensity and duration of the exercise stimulus and environmental factors or air quality.
“Ultimately, a personalized, evidence-based approach that acknowledges both the hormetic nature of exercise-induced oxidative stress and the complex biology of antioxidant action offers the greatest potential to optimize health and performance outcomes,” the researchers noted.
They added that dietary supplementation is best reserved for correcting nutrient insufficiencies or managing periods of high training distress and that only a few of the compounds marketed as antioxidants are backed by moderate-to-high quality evidence for improving recovery without hindering training adaptations.
The 10 official conclusions
The following conclusions represent the official position of the ISSN:
- Redox balance exists on a spectrum, with mild oxidative eustress driving beneficial adaptations, while excessive distress impairing recovery and performance.
- Exercise-induced ROS can support adaptation at moderate levels but may cause muscle damage, inflammation and reduced endurance when excessive.
- Antioxidants from endogenous systems and dietary sources protect cells by neutralizing free radicals and limiting oxidative damage to key biomolecules.
- FDA labeling for “antioxidant” claims applies to nutrients with established RDIs and demonstrated antioxidant activity; this typically includes vitamins C and E, β-carotene (a source of vitamin A), selenium, zinc, copper and manganese.
- Several dietary compounds exhibit antioxidant activity, showing potential for both direct and indirect antioxidant effects. However, the strength of evidence varies, and their use should be tailored to align with specific performance or recovery goals.
- Regular exercise improves endogenous antioxidant defenses and should be the primary strategy for enhancing redox capacity before considering supplementation.
- Whole foods rich in flavonoids, polyphenols, carotenoids, vitamins and minerals are the preferred antioxidant sources, with supplements used to fill dietary gaps.
- Supplementation is best reserved for nutrient insufficiencies and deficiencies, inadequate dietary intake, or periods of high stress, while chronic high-dose use may blunt training adaptations.
- Responses to supplementation vary by individual factors such as training status, baseline antioxidant capacity, demographics, diet and injury risk, with some compounds offering cognitive, behavioral or trauma-related benefits in specific populations.
- Supplements such as creatine (i.e. 0.1 g/kg/day), omega-3 fatty acids (1000–6000 mg/day EPA+DHA for 6–12 weeks), tart cherry (480 mg powder or 60–90 mL juice/day for 7–14 days) and astaxanthin (4–12 mg/day for 4–12 weeks) rank among the top nutrients for their antioxidant effects, with moderate- to high-quality evidence supporting their use in recovery or performance without interfering with training adaptations. Most others exhibit weak or mixed data; therefore, selection should be tailored to training goals, biology and the strength of the evidence.
Source: Journal of the International Society of Sports Nutrition. doi: 10.1080/15502783.2026.2629828. “International Society of Sports Nutrition position stand: effects of dietary antioxidants on exercise and sports performance”. Authors: Gonzalez, D. E. et al.
