Supplements

Antioxidant Supplementation in Exercise and Sports Performance: The 2026 Official ISSN Position Stand

Updated: July 22, 2026

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The International Society of Sports Nutrition (ISSN) has officially released its updated 2026 Position Stand regarding the role of dietary antioxidants in exercise and sports performance. The comprehensive review was authored by a team of leading exercise scientists including Drew E. Gonzalez, Broderick L. Dickerson, Brandon M. Roberts, and colleagues.

Video: Dr. Layne Norton (Biolayne) explains more on this topic (YouTube).

This statement provides an evidence-based synthesis to address a major question among athletes and fitness enthusiasts: Should athletes take antioxidant supplements (such as Vitamin C, Vitamin E, polyphenols, etc.)?

1. The Concept of Hormesis: Reactive Oxygen Species Are Not Purely Harmful

Historically, reactive oxygen and nitrogen species (ROS/RNS) generated during physical exertion were viewed solely as damaging free radicals causing cellular damage and muscle soreness. However, the ISSN highlights the principle of Redox Balance grounded in hormesis:

Eustress (Beneficial Stress): Moderate exercise-induced oxidative stress acts as a vital signaling mechanism. It triggers natural biochemical adaptations, promoting mitochondrial biogenesis, endurance adaptations, muscle hypertrophy, and upregulating endogenous antioxidant defenses.
Distress (Harmful Stress): Excessive oxidative stress (resulting from overtraining, acute high-intensity competition density, sleep deprivation, or severe environmental pollution) can damage cellular membranes, impair immune function, and delay recovery.

2. The Risk of Supraphysiological Doses

A key takeaway from the 2026 ISSN Position Stand is that high-dose antioxidant supplementation can blunt training adaptations:

Consuming high-dose antioxidant supplements (e.g., Vitamin C ≥ 1000 mg/day or high-dose Vitamin E) around exercise windows quenches necessary ROS signaling.
Consequently, this blunts mitochondrial biogenesis, training-induced endurance adaptations, and muscle hypertrophy.

3. Practical Recommendations from the ISSN

The ISSN outlines a targeted, individualized strategy:

Primary Strategy: A Food-First Approach

The ISSN recommends that athletes fulfill their antioxidant needs primarily through a varied diet rich in whole foods, including fruits, vegetables, nuts, and whole grains. Whole foods provide a natural matrix of phytochemicals that act synergistically without disrupting redox homeostasis.

When Is Targeted Supplementation Warranted?

Exogenous antioxidant supplementation should only be considered under specific circumstances:

Diagnosed Micronutrient Deficiency: When clinical or nutritional assessment confirms a specific deficiency.
High-Density Competition / Weight Making: During rapid multi-stage tournaments, controlled overreaching phases, or acute weight-making periods in combat sports.
Extreme Environments: Training or competing at high altitude or in heavily polluted environments where oxidative stress exceeds natural adaptation capacity.

4. Key Takeaways

Recreational Lifters / General Fitness: Routine consumption of high-dose Vitamin C/E to prevent muscle soreness is unnecessary and counterproductive. Focus on a colorful, plant-dense diet.
Elite Athletes: Any targeted antioxidant supplementation strategy should be timed and dosed precisely under the guidance of a sports dietitian.