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Supplements with evidence: for which effort, with what limits

Nutrition8 min read
On this page
  1. Three questions, in order
  2. What has evidence, for which effort
  3. Deficiencies: iron and vitamin D
  4. Anti-doping and contamination
  5. BCAA and EAA: why they are not among the proven ergogenic aids
  6. Before using anything
  7. How we reviewed it
  8. Sources

Three questions, in order

The IOC consensus (2018) separates supplements by purpose: correcting deficiencies, supplying energy and macronutrients conveniently, giving a direct performance benefit, and supporting training. Only a few products in the third group have good evidence: caffeine, creatine, specific buffering agents and nitrate. Responses vary a lot between people and depend on the situation of use.1 The AIS framework follows the same logic: level of evidence, use in defined situations and advice from a sports dietitian.2

  1. Does it work for my effort? Duration and intensity matter more than the ingredient name.
  2. Is it safe for me? Side effects, medicines, health conditions.
  3. Is it allowed and is the product checked? See the anti-doping section.

What has evidence, for which effort

Caffeine

  • Efforts with evidence: Aerobic endurance is among the most consistent areas; other efforts vary
  • Doses studied (not prescriptions): Often 3-6 mg/kg, about 60 minutes before
  • Limits and side effects: Individual response, sleep, total from all sources. Details in the caffeine guide.

Nitrate (beetroot and similar)

  • Efforts with evidence: Time-trial and time-to-exhaustion tests. Smaller effect in people with a VO₂peak above 60 ml/kg/min
  • Doses studied (not prescriptions): 2022 expert consensus: 8-16 mmol once, last dose 2-4 hours before; 4-16 mmol a day if chronic
  • Limits and side effects: For safety the experts suggest favouring vegetables and vegetable juices. Up to about 16 mmol once is considered safe; chronic use needs more study. For most statements assessed, evidence was insufficient.

Sodium bicarbonate

  • Efforts with evidence: Intense efforts of 30 seconds to 12 minutes: cycling, running, swimming, rowing, combat sports, muscular endurance
  • Doses studied (not prescriptions): ISSN 2021: 0.2-0.5 g/kg; 0.3 g/kg appears optimal, 60-180 minutes before; 3-7 day protocols described
  • Limits and side effects: Bloating, nausea, vomiting, abdominal pain, which can hurt the performance. The source does not establish an acute performance effect for efforts longer than 12 minutes.

Beta-alanine

  • Efforts with evidence: 1-4 minute efforts, mostly time trials; reduces neuromuscular fatigue
  • Doses studied (not prescriptions): ISSN 2015: 4-6 g a day for at least 2-4 weeks
  • Limits and side effects: Tingling (paraesthesia), reduced with split doses or sustained release. More studies needed on efforts beyond 25 minutes and on strength.

Creatine monohydrate

  • Efforts with evidence: Intense repeated exercise, strength and power, adaptations to strength training
  • Doses studied (not prescriptions): Not reported here: the sources separate loading, maintenance and safety data, and there is no single dose to quote (see source 3)
  • Limits and side effects: ISSN 2017 reports weight gain as the only consistent side effect, in the populations studied; a 2024 paper from the ISSN group judges it safe and effective in general. It is not a guarantee for every person: with health conditions or medicines, ask a doctor. Weight gain can matter in sports where weight matters.3

By discipline: in STRENGTH the ingredient with the clearest evidence is creatine, for strength-training adaptations. That is different from an acute benefit in a race. For long RUN and RIDE efforts, caffeine and carbohydrate have the most solid picture and nitrate has evidence with limits. For intense efforts up to 12 minutes, such as a pool race or a short time trial, bicarbonate has evidence; beta-alanine has evidence mainly in 1-4 minute efforts. These describe the evidence, not a recommended stack: interactions between ingredients are unclear, except that the ISSN notes possible additive effects of bicarbonate with creatine or beta-alanine.3

Deficiencies: iron and vitamin D

The IOC is clear: a real iron or vitamin D deficiency can reduce performance, directly or by limiting training or bone health. In that case supplementing makes sense, after an assessment and with follow-up. It is not a supplement to improve performance in someone without a deficiency. For vitamin D the consensus warns that high doses need monitoring to avoid toxicity. That is why there are no doses here: a suspected deficiency needs a medical assessment, not a purchase.1 The AIS places iron and vitamin D in the same Group A, for identified athletes with protocols, not for general use.2

Anti-doping and contamination

The WADA Prohibited List changes every year. The 2026 List is in force from 1 January 2026; the 2027 List, approved on 10 September 2026 and published on 21 September, comes into force on 1 January 2027.5 What counts is the list in force on the date of the race. In the 2026 Monitoring Program caffeine is not considered a prohibited substance.4 For 2027, the US anti-doping agency (USADA) advisory lists caffeine in the 2027 Monitoring Program, so not prohibited; the WADA PDF of the 2027 list was not read, so for the other ingredients on this page nothing is claimed for either year.9 Check the list for the date of your race.

The IOC names inadvertent intake of prohibited substances from supplements as a known risk. A useful ingredient does not make every brand or batch safe. WOLF LAB does not certify products or batches and recommends no brands here.1

BCAA and EAA: why they are not among the proven ergogenic aids

BCAAs (leucine, isoleucine, valine) are three of the nine essential amino acids. A 2022 systematic review of 24 studies in athletes and regular trainers found they tend to activate anabolic signals, but the benefits on performance and body composition were negligible. In people doing resistance training they reduced muscle soreness after exercise; in endurance sports results were inconsistent. Many studies did not report total daily protein, so the benefits need cautious reading.6 The AIS places them in Group C: evidence not supportive of a benefit in athletes, or too little research for an informed opinion.7 That does not mean they are useless in every sense: it means there is no proven benefit on race performance.

EAAs include all nine essential amino acids, BCAAs included. The 2023 ISSN position names stimulating muscle protein synthesis as their main role, and says free-form EAAs stimulate it more than the same amount of intact protein. The conclusions concern muscle maintenance and protein synthesis, not a proven benefit on race performance. The same document notes that EAA requirements rise in a calorie deficit.8 Protein synthesis and energy in a race are two different goals: with EAAs, as with BCAAs, you are not taking in carbohydrate. Total daily protein matters for protein synthesis as well.

Before using anything

  • Start from food and a review of your diet, not from the product.
  • A supplement meant for performance should be tried in training or a simulated race before a real race, because responses vary.1
  • For carbohydrate and fluids in the race use the dedicated tools: Fuel and the article on marathon carbohydrates.

How we reviewed it

Document review of the sources: IOC consensus, ISSN position stands, expert consensus on nitrate, systematic review on BCAA and AIS and WADA pages. No WOLF LAB tests.

Limits. Evidence quality differs by ingredient. Doses are those reported in the studies, not prescriptions. WADA 2026 and 2027 lists: for ingredients other than caffeine check the list on the race date; the 2027 list PDF was not read.

Sources

  1. Maughan RJ et al. IOC consensus statement: dietary supplements and the high-performance athlete. British Journal of Sports Medicine, 2018. PMC.
  2. AIS (Australian Sports Commission). Sports supplements, Group A. AIS.
  3. Grgic J et al. ISSN position stand: sodium bicarbonate and exercise performance, 2021. PubMed. Trexler ET et al. ISSN position stand: beta-alanine, 2015. PubMed. Kreider RB et al. ISSN position stand: safety and efficacy of creatine supplementation, 2017. PubMed. Antonio J et al. Common questions and misconceptions about creatine supplementation, Part II, 2024. PMC. Nitrate: Dietary inorganic nitrate as an ergogenic aid: an expert consensus derived via the modified Delphi technique, Sports Medicine, 2022. PMC.
  4. WADA. The Prohibited List (2026) and Monitoring Program. WADA.
  5. WADA. WADA publishes 2027 Prohibited List, 21 September 2026. WADA. The 2027 Code and Standards (in force from 1 January 2027) are a different document from the list.
  6. Martinho DV et al. Oral branched-chain amino acids supplementation in athletes: a systematic review, Nutrients, 2022. PMC.
  7. AIS. Sports supplements, Group C. AIS.
  8. Ferrando AA et al. ISSN position stand: essential amino acid supplementation on skeletal muscle and performance, 2023. PMC.
  9. USADA. Athlete advisory: what's new on the 2027 WADA Prohibited List?, 6 October 2026. USADA. Secondary source.

Sources consulted on 31 October 2026. Doses are those reported in the studies and consensus statements, not prescriptions. No WOLF LAB tests.

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