Should athletes use antioxidant supplements for performance?
Learn to train smart, run fast, and be strong with this endurance performance nerd alert from Thomas Solomon, PhD.
International Society of Sports Nutrition position stand: effects of dietary antioxidants on exercise and sports performance
Gonzalez et al. (2026) J Int Soc Sports Nutr (click here to open the original paper)
How can you apply this paper's findings to your training or coaching practice?
◦ The useful bit is the nuance: antioxidants are not “good” or “bad.” The authors frame exercise redox biology as a spectrum where a little oxidative stress helps adaptation, and too much can slow recovery and performance. That framing matters for real-world coaching because it pushes you to match the tool to the job: if you’re deep in heavy training, travel, poor sleep, altitude, or back-to-back events, “recovery help” with some antioxidants might be a reasonable goal. However, if you’re trying to force adaptation in a build phase, chronic high-dose antioxidant supplementation might be a zero-sum game.
◦ Practically, the authors flag a small “top tier” of supplements that looks most defensible for recovery or performance without obvious adaptation blunting: Creatine (0.1 grams per kilogram per day), Omega-3 fatty acids (1000 to 6000 milligrams per day of EPA & DHA for 6 to 12 weeks), tart cherry (480 milligrams powder or 60 to 90 milliliters juice per day for 7 to 14 days), and astaxanthin (4 to 12 milligrams per day for 4 to 12 weeks). However, you should consider these supplements in line with your performance goal (e.g., Creatine is likely to boost maximal strength, reps-to-failure that last under about 3 minutes, and all-out speed efforts up to roughly 30 seconds, but is unlikely to improve endurance performance during time trials or time-to-exhaustion runs).
What is my Rating of Perceived scientific Enjoyment (RPsE)?
5 out of 10 → I experienced low to moderate scientific enjoyment because although the paper clearly explains mechanisms, provides practical dosing examples for many compounds, and provides clear takeaways, it lacks a reproducible evidence audit — there is no systematic search strategy, protocol pre-registrationPreregistration is when a detailed description of a study plan is deposited in an open-access repository before collecting the study data. It promotes transparency and accountability, and boosts research integrity. Without preregistration, it is easier for scientists to change outcomes after seeing the data, selectively report “exciting” results, or run many analyses and only show the ones that work, which can introduce bias and weaken the trustworthiness of the findings., formal risk of biasRisk of bias in a meta-analysis refers to the potential for systematic errors in the studies included in the analysis. Such errors can lead to misleading/invalid results and unreliable conclusions. This can arise because of issues with the way participants are selected (randomisation), how data is collected and analysed, and how the results are reported. assessment, publication biasPublication bias in meta-analysis occurs when studies with significant results are more likely to be published than those with non-significant findings, leading to distorted conclusions. This bias can inflate effect sizes and misrepresent the true effectiveness of interventions, making it crucial to identify and correct for it in research. assessment, or a GRADEGRADE, which stands for Grading of Recommendations Assessment, Development and Evaluation, is a standardised and structured approach used to assess the certainty of evidence in meta-analyses. It evaluates how “confident” researchers are in the results of studies and the recommendations that follow from them. GRADE rates a body of evidence as “high”, “moderate”, “low”, or “very low” certainty using a set of standardised criteria.-style assessment of the certainty of evidenceCertainty of evidence tells us how confident we are that the published results accurately reflect the true effect. It’s based on factors like study design, risk of bias, consistency, directness, precision, and publication bias. High certainty means that the current evidence is so strong and consistent that future studies are unlikely to change conclusions. Whereas, low certainty means more doubt and less confidence, and that future studies could easily change current conclusions. — so the “how sure are we?” info stays pretty cloudy.
Remember: Don’t make any major changes to your daily habits based on the findings of one study, especially if the study is small (e.g., less than 30 participants in a randomised controlled trial or less than 5 studies in a meta-analysis) or if the study is poor quality (e.g., has a high risk of biasRisk of bias in meta-analysis refers to the potential for systematic errors in the studies included in the analysis, which can lead to misleading or invalid results. Assessing this risk is crucial to ensure the conclusions drawn from the combined data are reliable. or a low quality of evidenceA low quality of evidence means that, in general, studies in this field have several limitations. This could be due to inconsistency in effects between studies, a large range of effect sizes between studies, and/or a high risk of bias (caused by inappropriate controls, a small number of studies, small numbers of participants, poor/absent randomization processes, missing data, inappropriate methods/statistics). When the quality of evidence is low, there is more doubt and less confidence in the overall effect of an intervention, and future studies could easily change overall conclusions. The best way to improve the quality of evidence is for scientists to conduct large, well-controlled, high-quality randomized controlled trials.). Always check what other trials in this field (link opens a new tab) have shown. Do they confirm the findings of this study? If there is a high-quality meta-analysis (link opens a new tab) evaluating the entirety of the evidence in this field, what does it say about the effect sizeA standardised measure of the magnitude of an effect of an intervention. Unlike p-values, effect sizes show the size of the effect and how meaningful it might be. Common effect size measures include standardised mean difference (SMD), Cohen’s d, Hedges’ g, eta-squared, and correlation coefficients., the risk of biasRisk of bias in a meta-analysis refers to the potential for systematic errors in the studies included in the analysis. Such errors can lead to misleading/invalid results and unreliable conclusions. This can arise because of issues with the way participants are selected (randomisation), how data is collected and analysed, and how the results are reported., and the quality/certainty of evidenceCertainty of evidence tells us how confident we are that the results reflect the true effect. It’s based on factors like study design, risk of bias, consistency, directness, and precision. Low certainty means more doubt and less confidence, and that future studies could easily change the conclusions. High certainty means that the current evidence is so strong and consistent that future studies are unlikely to change conclusions.?
What type of study is this?
◦ This study is a position standA position stand is a detailed policy recommendation published by a society that describes a course of action for practice. built from a society-led narrative review that was edited into a consensus statementA consensus statement is a collective opinion of a society that is used to develop evidence-based guidelines..
What was the authors’ hypothesis or research question?
◦ The authors aimed to explain how dietary antioxidants affect exercise-induced oxidative stress, training adaptation, recovery, and performance, and to rate common antioxidants by strength of evidence.
What did the authors do to test the hypothesis or answer the research question?
◦ The authors describe a society process (from the International Society of Sports Nutrition) where an invited writing team conducted a “comprehensive literature review”, drafted the paper, obtained review and comments from leading scholars, then revised it into a society-approved statement. The paper explains antioxidant biology in in vivoIn a living organism, such as a human or animal. exercise contexts, discusses how reactive species can both help and harm, and then walks through many specific antioxidants with suggested doses, durations, and a rough evidence grade for performance and antioxidant-related outcomes.
What did the authors find?
◦ The core finding is conceptual: a moderate amount of exercise-induced oxidative stress can be part of the adaptation signal, while excessive oxidative stress can contribute to fatigue, muscle damage, inflammation, and impaired performance and immune function. That’s why the authors prefer whole-food antioxidant sources and recommend supplements mainly for gaps, deficiencies, or periods of unusually high training stress.
◦ Creatine is rated high for performance benefits, while its antioxidant-related effects are rated weak to moderate. Some included studies show reduced inflammation signals after hard endurance events, but the antioxidant biomarker story is mixed.
◦ Omega-3 fatty acids are rated moderate for performance and moderate to high for antioxidant-related outcomes, mainly because the broader clinical literature shows improvements in antioxidant capacity and inflammation markers, and several exercise trials suggest less muscle damage and soreness in some settings. Effects look small to moderate overall, and not every trial agrees.
◦ Tart cherry is rated moderate to high for performance and moderate for antioxidant outcomes. The paper leans on multiple trials plus meta-analyses suggesting better recovery and some endurance performance improvement when timed around strenuous exercise (days before, and sometimes shortly before). The effects sound small to moderate and likely most relevant when you are actually smashed from training.
◦ Astaxanthin is rated moderate for performance and weak to moderate for antioxidant outcomes. The authors highlight studies reporting reduced soreness and some favorable shifts in lactate, fat oxidation, and biomarkers after several weeks, though plenty of outcomes remain inconsistent. Also: yes, it can turn your stool reddish if it is not fully absorbed — science can lead to pile of glamorous shit.
◦ The paper describes many other compounds as having weak or mixed evidence, and it explicitly warns that chronic high-dose antioxidant use (e.g., vitamins C and E) can blunt training adaptations, even though antioxidant biomarker effects can look moderate to high. For example, high-dose combinations over weeks can blunt training adaptation signals. So, if you’re chasing long-term gains, chronic megadoses are “not the droids you’re looking for.”
◦ The paper also acknowledges that responses vary by training status, baseline diet, and other individual factors—so two athletes can take the same thing and get different results, which is annoying but also, sadly, very on-brand for human biology.
◦ The authors concluded that antioxidants can support recovery in high-stress training contexts, but chronic high-dose supplementation can sometimes interfere with training adaptations, so decisions should be individualized, food-forward, and timed to goals.
What were the strengths?
◦ The paper’s big strength is usefulness: it explains the hormesis-style logic (why “some stress is good”) and then translates that into practical recommendations, including when supplementation makes sense (deficiencies, dietary gaps, heavy training distress) and which options appear most promising. It also states how the society produced and approved the document, which at least tells you there was structured expert review rather than a single-author hot take.
What were the limitations?
◦ The authors’ approach did not include a systematic reviewA systematic review answers a specific research question by systematically collating all known experimental evidence, which is collected according to pre-specified eligibility criteria. A systematic review helps inform decisions, guidelines, and policy. or a meta-analysisA meta-analysis quantifies the overall effect size of a treatment by compiling effect sizes from all known studies of that treatment., so it does not report database searches, a reproducible search strategy, or a formal risk of biasRisk of bias in a meta-analysis refers to the potential for systematic errors in the studies included in the analysis. Such errors can lead to misleading/invalid results and unreliable conclusions. This can arise because of issues with the way participants are selected (randomisation), how data is collected and analysed, and how the results are reported. and certainty of evidenceCertainty of evidence tells us how confident we are that the published results accurately reflect the true effect. It’s based on factors like study design, risk of bias, consistency, directness, precision, and publication bias. High certainty means that the current evidence is so strong and consistent that future studies are unlikely to change conclusions. Whereas, low certainty means more doubt and less confidence, and that future studies could easily change current conclusions. rating (such as GRADEGRADE, which stands for Grading of Recommendations Assessment, Development and Evaluation, is a standardised and structured approach used to assess the certainty of evidence in meta-analyses. It evaluates how “confident” researchers are in the results of studies and the recommendations that follow from them. GRADE rates a body of evidence as “high”, “moderate”, “low”, or “very low” certainty using a set of standardised criteria.). That makes the evidence ratings more interpretive than auditable. Also, some of the dosing ranges presented across antioxidants are extremely broad (the paper itself notes this issue), which can dilute practical clarity for readers trying to pick an evidence-aligned dose.
How was the study funded, and are there any conflicts of interest that may influence the findings?
◦ The authors report that no funding was provided for the paper. They also disclose extensive supplement-related relationships across multiple authors (research grants/funding related to dietary supplements; paid consulting and honoraria for one author; a patent held by one author; one author serving as the CEO of the ISSN; and one author employed by AstaReal Inc.). None of that automatically invalidates the conclusions, but it does mean you should read the “top tier” supplement endorsements with your eyebrows slightly raised.
Thanks for reading my “nerd alerts”. I’m passionate about equality in access to free education. Please leave me a 5-star review and follow @veohtu on Twitter/X, Facebook, and Instagram. Reviews and follows will train the magical algorithms to promote my content higher up the rankings so that more folks see high quality information.
Other papers I reviewed this month:
Does slow tempo strength training help runners race faster?
Does carbohydrate periodization boost running performance?
Does heavy lifting make cyclists faster?
Should athletes use antioxidant supplements for performance?
Niche Peach Connoisseur 5000 (from Sudden Death Brewing)
Additional papers I read that you might find interesting:
Whey protein intakes up to 0.4g/kg body mass are well tolerated before a 10km run at 85% of race pace: a clinical trial. Shaw et al. (2026) J Int Soc Sports Nutr.
Lower limb neuromotor control during perturbed and unperturbed gait conditions in male runners with Achilles tendinopathy: an exploratory analysis. Quarmby et al. (2026) Int Biomech.
National-Standard Middle-Distance Runners Maintain 1500 m Time Trial Running Performance on Successive Days. Birdsey et al. (2026) Eur J Sport Sci.
Dual-task effects on spatiotemporal, kinematic, and kinetic parameters and their variability during running. Teng et al. (2026) Gait Posture.
Morphological Changes and MRI Characteristics of the Achilles Tendon in Amateur Marathon Runners With Different Running Experience. Yao et al. (2026) J Foot Ankle Res.
Association between bone mineral density and ground reaction force in male and female runners. Smith et al. (2026) Gait Posture.
Effect of gait retraining in minimalist footwear or barefoot on running footstrike and cadence: a systematic review. DesRochers et al. (2026) Res Sports Med.
Does preferred technique influence how kinematics change during a run to exhaustion?-A cluster based approach. Rivadulla et al. (2026) PeerJ.
Biomechanical insights into Achilles tendinopathy risk and protection in runners: a large prospective study 4HAIE. Jandacka et al. (2026) Br J Sports Med.
Sprint running mechanics are associated with hamstring strain injury: a 6-month prospective cohort study of 126 elite male footballers. Bramah et al. (2026) Br J Sports Med.
Effect of high time under tension strength training on different muscular actions in the performance of runners: A randomized controlled trial. Martins et al. (2026) PLoS One.
The effect of a familiarization critical speed testing session on critical speed determination during treadmill running. Micheli et al. (2026) PLoS One.
Baseline Inflammatory Markers as Predictors of Running-Related Injuries: A One-Year Prospective 4HAIE Cohort Study. Cipryan et al. (2026) Scand J Med Sci Sports.
Stride-to-Stride Fluctuations and Temporal Patterns of Muscle Activity Exhibit a Stronger Relationship in Running-Induced Fatigue. Chalitsios et al. (2026) Scand J Med Sci Sports.
Examining attention- deficit/ hyperactivity disorder in endurance and ultra-endurance runners. Scheer et al. (2026) Acta Psychol (Amst).
"Running in circles": Breastfeeding experiences in women who have had bariatric surgery before pregnancy: A qualitative study. Mokhlesi et al. (2026) Women Birth.
Acute effects of dynamic stretching on knee joint position sense and dynamic balance in recreational runners: A randomized controlled trial. Simões et al. (2026) Gait Posture.
Carryover effects of treadmill-based footstrike modification gait retraining on overground running biomechanics. Chan et al. (2026) J Sports Sci.
Agreement and Reliability Between Urine Reagent Strips and Refractometry for Field Assessment of Hydration in Ultra-Trail Runners. Rojas-Valverde et al. (2026) Nutrients.
Effects of Marathon Running on Skin and Plasma Carotenoids in Endurance Runners. Joyner et al. (2026) Nutrients.
Share this nerd alert with your people:Access to education is a right, not a privilege
Equality in education, health, and sustainability matters deeply to me. I was fortunate to be born into a social welfare system in which higher education was free. Sadly, that's no longer true. That's why I created Veohtu: to make high-quality exercise science and sports nutrition education freely available to folks from all walks of life. All content is free and always will be. This nerd alert newsletter is part of that offering. Check out more free educational resources at veohtu.com.
Every day is a school day.
Empower yourself to train smart.
Be informed. Stay educated. Think critically.
