The Sports Supplements Tool from Thomas Solomon PhD.
What are the best supplements for runners and endurance athletes?
Last updated on: 15th July 2024.
Next update coming: July 2025.
Next update coming: July 2025.
Optimal performance is achieved with a well-planned and monitored training load combined with good nutrition, sleep, and rest. Lots of athletes also choose to use supplements. However, sports supplements are a big and confusing business — you can easily get lost and waste a lot of time and money. This free tool is an up-to-date summary of all known scientific evidence determining the effect of sports supplements on exercise performance. It can be used in combination with my Recovery Magic Tool. I’ve designed these resources for scientists, practitioners, coaches, and athletes to help inform their decisions. I aim to keep them up-to-date as new evidence emerges.
Is this your first time using this tool?
If yes, I strongly recommend reading the intro section below (500 words; 3 min read) because it contains important information about how you can learn to make informed decisions about choosing supplements. However, if you’ve already read the intro below, click the arrow to jump down to the tool.

To quote Louise Burke and John Hawley, “Modern sports nutrition offers a feast of opportunities to assist elite athletes to train hard, optimize adaptation, stay healthy and injury free, achieve their desired physique, and fight against fatigue factors that limit success.”. But, when I think about sports supplements, Ron Maughan’s poetry always rolls through my mind: “If it works, it’s probably banned… If it’s not banned, then it probably doesn’t work… There may be some exceptions.”
Functional claims about a specific product are usually made in line with a specific functional dose of the active ingredient. If a product doesn’t contain a sufficient dose then it definitely won’t have the intended effect. Since the FDA/FSA do not systematically monitor supplements, you will often read “This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.”. So, you need confidence in knowing exactly what’s in the bottle of pills or potion you are taking. And, as an athlete, quality control is essential! Without it, you may harm your health or take a contaminated product. And this is where things start to fall apart… Several reports have found major discrepancies between claimed contents and actual content (e.g. ephedra and CBD supplements), while even some controlled drugs, like the steroid hormone dehydroepiandrosterone (DHEA), have slipped through the net and been sold as dietary supplements. Plus, a 2022 systematic review found that 28% (or 875 out of 3132) supplements contained undeclared substances (including stimulants and anabolic steroids) that would trigger a positive doping test. This is worrying because, according to the NURMI study, ~50% of runners use supplements and a 2007 IAAF/World Athletics report found that ~85% of elite track and field athletes used dietary and/or sports supplements. The supplement business is booming!
“It definitely works!”
I've lost count of how many times I’ve heard social media influencers spew the “I've used this and it was awesome” narrative. Regrettably, such phrases are also spouted from the mouths of “reputable” athletes, coaches, and other practitioners including scientists, nutritionists, psychologists, physiologists, and medical doctors on podcast, radio, and TV interviews when talking about a new pill, potion, or device. Frustratingly, these folks rarely say what “it” works for, what “it” is being compared to, or whether using “it” made them objectively faster, stronger, or healthier. When you see such narratives, think to yourself:
Were appropriate baseline measurements made?
What were the baseline measurements?
When were the baseline measurements followed up?
Did the baseline measurements actually change after the intervention period?
Did the person make any other lifestyle changes during the intervention period?
Is the person being paid or sponsored to promote the product? And, so on…
To bring clarity where there is obscurity and help you understand whether “it” might actually improve performance and/or recovery, I’ve dug into all known scientific evidence on this topic and created a free resource to help inform your decisions.
High-quality robust evidence comes from studies with a randomized controlled trial (RCT) design. But, “cherry-picking” a study to confirm a bias is not a valid pursuit for informing practice. A systematic review examines all the “cherries” in a standardised way and, when the studies included in a systematic review are of high enough quality, a meta-analysis of all the available data can be completed. This produces an overall effect size along with a 95% confidence interval (the range of values the real effect size is likely to be found if the intervention is repeated) and a heterogeneity score (how variable the effect is). In simple words, a meta-analysis analyses all the “cherries” simultaneously to produce a useable effect size based on all available scientific evidence, enabling good decisions to be made. So, when I say that “I’ve dug into all known scientific evidence”, I mean that I’ve read all known systematic reviews and meta-analyses and summarised the evidence in this free resource: the Sports Supplements Tool.
But, before making any decisions, always conduct a cost-benefit analysis, where “cost” includes a combination of financial costs, time costs, moral costs, risk of contamination, potential performance impairment, and harm to health. For example:
If there is no benefit, there is no point in using the supplement.
If there is a benefit and no (or little) cost, use the supplement; you’d be foolish not to.
If the cost outweighs the benefit, do not proceed.
When making this kind of cost-benefit analysis, always remember that:
Taking a supplement does not “make” an athlete.
A supplement does not replace training.
A dietary supplement does not replace food.
There is no such thing as “exercise in a pill”.
It is also important to know that if you use supplements of any kind and/or prescription or over-the-counter drugs, you are also putting yourself at an increased risk of a positive test because they can contain prohibited substances. Minimise this risk by taking the following steps:
Educate yourself by completing European Athletics’ I Run Clean certification.
Familiarise yourself with the rules of your sport and with WADA’s prohibited list, which is updated every January.
If you are using ANY sports (or dietary) supplement, ensure it has been independently tested for prohibited substances by Informed Sport (or similar), and ensure you supplement contains what it is supposed to contain (see LabDoor) → If in doubt, spit it out!
If you are using ANY over-the-counter or prescribed drugs, ALWAYS know what you are taking and get in the habit of cross-checking the Global DRO to help determine whether you need a TUE (therapeutic use exemption).
And, once you’ve chosen a supplement, check the label to make sure that it contains the ingredient you want and doesn’t contain ingredients you don’t want (see this very useful image from Examine.com to help out with that process).
And, finally… Always remember that:
You are the only person responsible for what goes into your body.
Ignorance is not an excuse.
Stay educated. Be informed. Encourage others to do the same.
OK… You’re now ready for some science.

Functional claims about a specific product are usually made in line with a specific functional dose of the active ingredient. If a product doesn’t contain a sufficient dose then it definitely won’t have the intended effect. Since the FDA/FSA do not systematically monitor supplements, you will often read “This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.”. So, you need confidence in knowing exactly what’s in the bottle of pills or potion you are taking. And, as an athlete, quality control is essential! Without it, you may harm your health or take a contaminated product. And this is where things start to fall apart… Several reports have found major discrepancies between claimed contents and actual content (e.g. ephedra and CBD supplements), while even some controlled drugs, like the steroid hormone dehydroepiandrosterone (DHEA), have slipped through the net and been sold as dietary supplements. Plus, a 2022 systematic review found that 28% (or 875 out of 3132) supplements contained undeclared substances (including stimulants and anabolic steroids) that would trigger a positive doping test. This is worrying because, according to the NURMI study, ~50% of runners use supplements and a 2007 IAAF/World Athletics report found that ~85% of elite track and field athletes used dietary and/or sports supplements. The supplement business is booming!







To bring clarity where there is obscurity and help you understand whether “it” might actually improve performance and/or recovery, I’ve dug into all known scientific evidence on this topic and created a free resource to help inform your decisions.
High-quality robust evidence comes from studies with a randomized controlled trial (RCT) design. But, “cherry-picking” a study to confirm a bias is not a valid pursuit for informing practice. A systematic review examines all the “cherries” in a standardised way and, when the studies included in a systematic review are of high enough quality, a meta-analysis of all the available data can be completed. This produces an overall effect size along with a 95% confidence interval (the range of values the real effect size is likely to be found if the intervention is repeated) and a heterogeneity score (how variable the effect is). In simple words, a meta-analysis analyses all the “cherries” simultaneously to produce a useable effect size based on all available scientific evidence, enabling good decisions to be made. So, when I say that “I’ve dug into all known scientific evidence”, I mean that I’ve read all known systematic reviews and meta-analyses and summarised the evidence in this free resource: the Sports Supplements Tool.
But, before making any decisions, always conduct a cost-benefit analysis, where “cost” includes a combination of financial costs, time costs, moral costs, risk of contamination, potential performance impairment, and harm to health. For example:



When making this kind of cost-benefit analysis, always remember that:




It is also important to know that if you use supplements of any kind and/or prescription or over-the-counter drugs, you are also putting yourself at an increased risk of a positive test because they can contain prohibited substances. Minimise this risk by taking the following steps:




And, once you’ve chosen a supplement, check the label to make sure that it contains the ingredient you want and doesn’t contain ingredients you don’t want (see this very useful image from Examine.com to help out with that process).
And, finally… Always remember that:



OK… You’re now ready for some science.


Caffeine, aka 1,3,7-trimethylxanthine, is a psychoactive drug that acts as a stimulant. While caffeine plays a role in calcium transport in muscle cells, it primarily affects your central nervous system by preventing adenosine binding to its receptors. This essentially blocks the “motivation-dampening” effects of adenosine, allowing “motivating” neurotransmitters like dopamine to continue to be released.
But caffeine has side effects, which can include a speedy heart rate (tachycardia), heart palpitations, headache, insomnia, peeing more, nervousness, gastrointestinal problems, and so on. If you develop any such symptoms as a consequence of caffeine intake before, during, or after races, you’re probably using too much. These side effects combined with frequent media stories about the risks of caffeine-containing high-sugar energy drinks, beg the important question: cIs caffeine dangerous?
A 2017 systematic review of the potential adverse effects of caffeine concluded that “Consumption of up to 400 mg caffeine/day in healthy adults is not associated with overt, adverse cardiovascular effects, behavioral effects, reproductive and developmental effects, acute effects, or bone status. Evidence also supports consumption of up to 300 mg caffeine/day in healthy pregnant women as an intake that is generally not associated with adverse reproductive and developmental effects.”.
A 2017 umbrella review of meta-analyses concluded that “Coffee consumption seems generally safe within usual levels of intake”, and a 2022 systematic review of the side effects of caffeine supplementation in sport concluded that “Athletes using caffeine supplementation to enhance performance should be aware of both benefits and risks associated with the use of this substance in the sports context.” and that “From a practical perspective, supplementation with ~3.0 mg/kg of caffeine may be the dose of choice to combine the ergogenic benefits of caffeine with a low prevalence of side effects.”
Furthermore, a randomised controlled crossover trial published in 2023 in the New England Journal of Medicine, which included continuous ECG measurements for 2 weeks, found that drinking more caffeinated coffee than usual might increase the number of premature ventricular contractions but does not increase the number of unusual heart rhythms (atrial arrhythmias) in healthy adults.
So, caffeine is generally safe for most people if used within the recommended amounts.
Therefore, it is no surprise that a lot of people use caffeine as a way to start (and continue) their day. Bonjour, coffee. By extension, since endurance athletes are also people, we can assume that many athletes also indulge in a daily caffeine fix. But, we can be more objective and examine epidemiology. A survey of 24,808 adults in the National Health and Nutrition Examination Survey (NHANES) found that ~89% of US adults consume caffeine daily. Meanwhile, a 2022 survey of 254 endurance athletes found that 85% of athletes reported daily caffeine consumption (in beverages), 41% reported multiple daily caffeine intake, but only 24% reported purposefully using caffeine supplements prior to or during sessions and races. So…
Does caffeine improve performance — what do the systematic reviews say?


















To conclude…

This tool is free. Please help keep it alive by buying me a beer:
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Full list of systematic reviews examining caffeine for performance.
Here is the list of systematic reviews I have summarised above.
Effect of Acute Caffeine Intake on Fat Oxidation Rate during Fed-State Exercise: A Systematic Review and Meta-Analysis. Fernández-Sánchez J, Trujillo-Colmena D, Rodríguez-Castaño A, Lavín-Pérez AM, Del Coso J, Casado A, Collado-Mateo D. Nutrients (2024)
Effects of Acute Ingestion of Caffeine Capsules on Muscle Strength and Muscle Endurance: A Systematic Review and Meta-Analysis. Wu W, Chen Z, Zhou H, Wang L, Li X, Lv Y, Sun T, Yu L. Nutrients (2024)
Caffeine, CYP1A2 Genotype and Exercise Performance: A Systematic Review and Meta-analysis. Barreto, Gabriel; Esteves, Gabriel P; Marticorena, Felipe; Oliveira, Tamires N; Grgic, Jozo; Saunders, Bryan. Med Sci Sports Exerc (2023)
The effect of caffeine on subsequent sleep: A systematic review and meta-analysis. Carissa Gardiner, Jonathon Weakley, Louise M. Burke, Gregory D. Roach, Charli Sargent, Nirav Maniar, Andrew Townshend, Shona L. Halson. Sleep Med Rev (2023)
International society of sports nutrition position stand: coffee and sports performance. Lowery et al. (2023) J Int Soc Sports Nutr
Effects of Caffeine Intake on Endurance Running Performance and Time to Exhaustion: A Systematic Review and Meta-Analysis. Ziyu Wang, Bopeng Qiu, Jie Gao, Juan Del Coso. Nutrients (2022)
Acute Effects of Caffeine on Overall Performance in Basketball Players-A Systematic Review. Anja Lazić, Miodrag Kocić, Nebojša Trajković, Cristian Popa, Leonardo Alexandre Peyré-Tartaruga, Johnny Padulo. Nutrients (2022)
Effect of Pre-Exercise Caffeine Intake on Endurance Performance and Core Temperature Regulation During Exercise in the Heat: A Systematic Review with Meta-Analysis. Catherine Naulleau, David Jeker, Timothée Pancrate, Pascale Claveau, Thomas A Deshayes, Louise M Burke, Eric D B Goulet. Sports Med (2022)
Exploring the minimum ergogenic dose of caffeine on resistance exercise performance: A meta-analytic approach. Jozo Grgic. Nutr (2022)
Risk or benefit? Side effects of caffeine supplementation in sport: a systematic review. Jefferson Gomes de Souza, Juan Del Coso, Fabiano de Souza Fonseca, Bruno Victor Corrêa Silva, Diego Brito de Souza, Rodrigo Luiz da Silva Gianoni, Aleksandra Filip-Stachnik, Julio Cerca Serrão, João Gustavo Claudino. Eur J Nutr (2022)
Effects of acute caffeine intake on combat sports performance: A systematic review and meta-analysis. Javier Diaz-Lara, Jozo Grgic, Daniele Detanico, Javier Botella, Sergio L Jiménez, Juan Del Coso. Crit Rev Food Sci Nutr (2022)
Effects of caffeine on rate of force development: A meta-analysis. Jozo Grgic, Pavle Mikulic. Scand J Med Sci Sports (2022)
Supplementation and Performance for Wheelchair Athletes: A Systematic Review. Andreia Bauermann, Karina S G de Sá, Zilda A Santos, Anselmo A Costa E Silva. Adapt Phys Activ Q (2022)
Acute caffeine supplementation and live match-play performance in team-sports: A systematic review (2000-2021). Adriano Arguedas-Soley, Isobel Townsend, Aaron Hengist, James Betts. J Sports Sci (2022)
Interaction Between Caffeine and Creatine When Used as Concurrent Ergogenic Supplements: A Systematic Review. Sara Elosegui, Jaime López-Seoane, María Martínez-Ferrán, Helios Pareja-Galeano. Int J Sport Nutr Exerc Metab (2022)
Synergy of carbohydrate and caffeine ingestion on physical performance and metabolic responses to exercise: A systematic review with meta-analysis. Jaime López-Seoane, Marta Buitrago-Morales, Sergio L Jiménez, Juan Del Coso, Helios Pareja-Galeano. . Crit Rev Food Sci Nutr (2022)
Does Caffeine Increase Fat Metabolism? A Systematic Review and Meta-Analysis. Scott A. Conger, Lara M. Tuthill, Mindy L. Millard-Stafford. Int J Sport Nutr Exerc Metab (2022)
Effects of Caffeine Intake on Endurance Running Performance and Time to Exhaustion: A Systematic Review and Meta-Analysis. Ziyu Wang, Bopeng Qiu, Jie Gao, and Juan Del Coso. Nutrients (2022)
Acute Effects of Caffeine Supplementation on Physical Performance, Physiological Responses, Perceived Exertion, and Technical-Tactical Skills in Combat Sports: A Systematic Review and Meta-Analysis. Slaheddine Delleli, Ibrahim Ouergui, Hamdi Messaoudi, Khaled Trabelsi, Achraf Ammar, Jordan M. Glenn and Hamdi Chtourou. Nutrients (2022)
Effects of caffeine ingestion on cardiopulmonary responses during a maximal graded exercise test: a systematic review with meta-analysis and meta-regression. Alisson Henrique Marinho, João Paulo Lopes-Silva, Gislaine Cristina-Souza, Filipe Antônio de Barros Sousa, Thays Ataide-Silva, Adriano Eduardo Lima-Silva, Gustavo Gomes de Araujo, Marcos David Silva-Cavalcante. Crit Rev Food Sci Nutr (2022)
Effects of caffeine chewing gum supplementation on exercise performance: A systematic review and meta-analysis. G Barreto, L M R Loureiro, C E G Reis, B Saunders. Eur J Sport Sci (2022)
Can I Have My Coffee and Drink It? A Systematic Review and Meta-analysis to Determine Whether Habitual Caffeine Consumption Affects the Ergogenic Effect of Caffeine. Arthur Carvalho, Felipe Miguel Marticorena, Beatriz Helena Grecco, Gabriel Barreto, Bryan Saunders. Sports Med (2022)
Effects of caffeine on isometric handgrip strength: A meta-analysis. Jozo Grgic. Clin Nutr ESPEN (2022)
International society of sports nutrition position stand: caffeine and exercise performance. Nanci S Guest, Trisha A VanDusseldorp, Michael T Nelson Jozo Grgic, Brad J Schoenfeld, Nathaniel D M Jenkins, Shawn M Arent, Jose Antonio, Jeffrey R Stout, Eric T Trexler, Abbie E Smith-Ryan, Erica R Goldstein, Douglas S Kalman, Bill I Campbell. J Int Soc Sports Nutr (2021)
Ergogenic Effects of Acute Caffeine Intake on Muscular Endurance and Muscular Strength in Women: A Meta-Analysis. Jozo Grgic, Juan Del Coso. Int J Environ Res Public Health (2021)
Does Acute Caffeine Supplementation Improve Physical Performance in Female Team-Sport Athletes? Evidence from a Systematic Review and Meta-Analysis. Alejandro Gomez-Bruton, Jorge Marin-Puyalto, Borja Muñiz-Pardos, Angel Matute-Llorente, Juan Del Coso, Alba Gomez-Cabello, German Vicente-Rodriguez, Jose A Casajus, Gabriel Lozano-Berges. Nutrients (2021)
Does Acute Caffeine Supplementation Improve Physical Performance in Female Team-Sport Athletes? Evidence from a Systematic Review and Meta-Analysis. Alejandro Gomez-Bruton, Jorge Marin-Puyalto, Borja Muñiz-Pardos, Angel Matute-Llorente, Juan Del Coso, Alba Gomez-Cabello, German Vicente-Rodriguez, Jose A Casajus, Gabriel Lozano-Berges. Nutrients (2021)
Caffeinated Drinks and Physical Performance in Sport: A Systematic Review. Sergio L Jiménez, Javier Díaz-Lara, Helios Pareja-Galeano, Juan Del Coso. Nutrients (2021)
Ergogenic Effects of Acute Caffeine Intake on Muscular Endurance and Muscular Strength in Women: A Meta-Analysis. Grgic J, Del Coso J. Int J Environ Res Public Health (2021)
Is caffeine mouth rinsing an effective strategy to improve physical and cognitive performance? A systematic review. da Silva WF, Lopes-Silva JP, Camati Felippe LJ, Ferreira GA, Lima-Silva AE, Silva-Cavalcante MD. Crit Rev Food Sci Nutr (2021)
Caffeine and Cognitive Functions in Sports: A Systematic Review and Meta-Analysis. Lorenzo Calvo J, Fei X, Domínguez R, Pareja-Galeano H. Nutrients (2021)
Nonplacebo Controls to Determine the Magnitude of Ergogenic Interventions: A Systematic Review and Meta-analysis.
Marticorena FM, Carvalho A, de Oliveira LF, Dolan E, Gualano B, Swinton P, Saunders B. Med Sci Sports Exerc (2021)
CYP1A2 genotype and acute ergogenic effects of caffeine intake on exercise performance: a systematic review. Grgic J, Pickering C, Del Coso J, Schoenfeld BJ, Mikulic P. Eur J Nutr (2021)
Effects of diet interventions, dietary supplements, and performance-enhancing substances on the performance of CrossFit-trained individuals: A systematic review of clinical studies. Dos Santos Quaresma MVL, Guazzelli Marques C, Nakamoto FP. Nutrition (2021)
Effect of Acute Caffeine Intake on the Fat Oxidation Rate during Exercise: A Systematic Review and Meta-Analysis. Collado-Mateo D, Lavín-Pérez AM, Merellano-Navarro E, Coso JD. Nutrients (2020)
Effect of Supplements on Endurance Exercise in the Older Population: Systematic Review. Martínez-Rodríguez A, Cuestas-Calero BJ, Hernández-García M, Martíez-Olcina M, Vicente-Martínez M, Rubio-Arias JÁ. Int J Environ Res Public Health (2020)
The Effects of Caffeine Mouth Rinsing on Exercise Performance: A Systematic Review. Ehlert AM, Twiddy HM, Wilson PB. Int J Sport Nutr Exerc Metab (2020)
Effects of caffeine supplementation on muscle endurance, maximum strength, and perceived exertion in adults submitted to strength training: a systematic review and meta-analyses. Ferreira TT, da Silva JVF, Bueno NB. Crit Rev Food Sci Nutr (2020)
Acute Effects of Caffeine Supplementation on Movement Velocity in Resistance Exercise: A Systematic Review and Meta-analysis. Raya-González J, Rendo-Urteaga T, Domínguez R, Castillo D, Rodríguez-Fernández A, Grgic J. Sports Med (2020)
The Effects of Caffeine Ingestion on Measures of Rowing Performance: A Systematic Review and Meta-Analysis. Grgic J, Diaz-Lara FJ, Coso JD, Duncan MJ, Tallis J, Pickering C, Schoenfeld BJ, Mikulic P. Nutrients (2020)
Is Caffeine Recommended Before Exercise? A Systematic Review To Investigate Its Impact On Cardiac Autonomic Control Via Heart Rate And Its Variability. Benjamim CJR, Kliszczewicz B, Garner DM, Cavalcante TCF, da Silva AAM, Santana MDR, Valenti VE. J Am Coll Nutr (2020)
Isolated effects of caffeine and sodium bicarbonate ingestion on performance in the Yo-Yo test: A systematic review and meta-analysis. Grgic J, Garofolini A, Pickering C, Duncan MJ, Tinsley GM, Del Coso J. J Sci Med Sport (2020)
Wake up and smell the coffee: caffeine supplementation and exercise performance-an umbrella review of 21 published meta-analyses. Grgic J, Grgic I, Pickering C, Schoenfeld BJ, Bishop DJ, Pedisic Z. Br J Sports Med (2020)
Effect of Caffeine Supplementation on Sports Performance Based on Differences Between Sexes: A Systematic Review. Juan Mielgo-Ayuso, Diego Marques-Jiménez, Ignacio Refoyo, Juan Del Coso, Patxi León-Guereño, Julio Calleja-González. Nutrients (2019)
The effects of caffeine ingestion on isokinetic muscular strength: A meta-analysis. Grgic J, Pickering C. J Sci Med Sport (2019)
Caffeine Supplementation and Physical Performance, Muscle Damage and Perception of Fatigue in Soccer Players: A Systematic Review. Mielgo-Ayuso J, Calleja-Gonzalez J, Del Coso J, Urdampilleta A, León-Guereño P, Fernández-Lázaro D. Nutrients (2019)
Effects of acute ingestion of caffeine on team sports performance: a systematic review and meta-analysis. Salinero JJ, Lara B, Del Coso J. Res Sports Med (2019)
Correction to: The Effect of Acute Caffeine Ingestion on Endurance Performance: A Systematic Review and Meta-Analysis. Southward K, Rutherfurd-Markwick KJ, Ali A. Sports Med (2018). Note: this article was originally published here but contained errors that were corrected in this revised version.
Effects of Coffee Components on Muscle Glycogen Recovery: A Systematic Review. Loureiro LMR, Reis CEG, da Costa THM. Int J Sport Nutr Exerc Metab (2018)
Caffeine and Physiological Responses to Submaximal Exercise: A Meta-Analysis. Glaister M, Gissane C. Int J Sports Physiol Perform (2018)
Caffeine ingestion enhances Wingate performance: a meta-analysis. Grgic J. Eur J Sport Sci (2018)
Coffee, caffeine, and sleep: A systematic review of epidemiological studies and randomized controlled trials. Ian Clark, Hans Peter Landolt. Sleep Med Rev (2017)
Acute effects of caffeine-containing energy drinks on physical performance: a systematic review and meta-analysis. Souza DB, Del Coso J, Casonatto J, Polito MD. Eur J Nutr (2017)
A systematic review of the efficacy of ergogenic aids for improving running performance. Schubert MM, Astorino TA. J Strength Cond Res (2013)
Does caffeine added to carbohydrate provide additional ergogenic benefit for endurance? Conger SA, Warren GL, Hardy MA, Millard-Stafford ML. Int J Sport Nutr Exerc Metab (2011)
Efficacy of acute caffeine ingestion for short-term high-intensity exercise performance: a systematic review. Astorino TA, Roberson DW. J Strength Cond Res (2010)
Effect of caffeine on sport-specific endurance performance: a systematic review. Ganio MS, Klau JF, Casa DJ, Armstrong LE, Maresh CM. J Strength Cond Res (2009)
Effects of caffeine ingestion on rating of perceived exertion during and after exercise: a meta-analysis. Doherty M, Smith PM. Scand J Med Sci Sports (2005 )


You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.




























































Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.



Some amino acids are coded by our genes, some are used to build proteins; others are not. Taurine is an amino acid produced in the body from the metabolism of the amino acid, cysteine, but it is not used as a “building block” for protein synthesis. Instead, it interacts with ion channels to stabilize cell membrane integrity and regulate osmoregulation (water transport). Taurine is also essential for cardiac muscle and skeletal muscle function. See Lambert et al. 2014 to read all about the physiology of taurine from one of my former colleagues in Copenhagen.
Besides producing taurine in the body, we also obtain taurine in our diet, primarily from meat, dairy, seafood, and algae-containing food, like seaweed (see here and here). Because taurine regulates calcium homeostasis and can increase calcium-binding proteins during muscle contraction, it is alleged to play a role in muscle strength and endurance. Therefore, taurine is the stimulant of choice in many “energy” drinks (e.g. RedBull). But…
Does taurine improve performance — what do the systematic reviews say?




To conclude…


This tool is free. Please help keep it alive by buying me a beer:
Want free info like this in your inbox? Sign up here:
Full list of systematic reviews examining taurine for performance.
Here is the list of systematic reviews I have summarised above.
The Dose Response of Taurine on Aerobic and Strength Exercises: A Systematic Review. Chen Q, Li Z, Pinho RA, Gupta RC, Ugbolue UC, Thirupathi A, Gu Y. Front Physiol (2021).
The Effects of an Oral Taurine Dose and Supplementation Period on Endurance Exercise Performance in Humans: A Meta-Analysis. Mark Waldron, Stephen David Patterson, Jamie Tallent, Owen Jeffries. Sports Med (2018)
Acute effects of caffeine-containing energy drinks on physical performance: a systematic review and meta-analysis. Diego B Souza, Juan Del Coso, Juliano Casonatto, Marcos D Polito. Eur J Nutr (2017)


You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.





Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.



Some amino acids are coded by our genes, some are used to build proteins; others are not. Creatine is a naturally occurring amino acid derivative but, unlike standard amino acids, it is not coded by our genes and it is not a protein building block. Instead, creatine is involved in energy metabolism. In humans, the vast majority (~95%) of creatine is found in our muscles. Our body can synthesise creatine from the amino acids, arginine and glycine, but because creatine is also degraded to creatinine and then excreted in our urine, we must also consume creatine in our diet to maintain adequate bodily levels. This can be achieved by eating meat (inc. red meat, chicken, pork, etc), fish (e.g. salmon) and seafood.

ATP hydrolysis: ATP → ADP + Pi + H+
ATP resynthesis: PCr → Cr + Pi then ADP + Pi → ATP
So, by having adequate muscle levels of creatine, you have the opportunity to produce phosphocreatine. Therefore, the creatine in your muscles helps maintain ATP availability for maximal-effort, anaerobic/sprint-type exercise. Since daily creatine supplementation increases its levels in your muscles, creatine has become a very popular supplement. So…
ATP resynthesis: PCr → Cr + Pi then ADP + Pi → ATP
Does creatine improve performance — what do the systematic reviews say?













To conclude…


This tool is free. Please help keep it alive by buying me a beer:
Want free info like this in your inbox? Sign up here:
Full list of systematic reviews examining creatine for performance.
Here is the list of systematic reviews I have summarised above.
The Effects of Creatine Supplementation Combined with Resistance Training on Regional Measures of Muscle Hypertrophy: A Systematic Review with Meta-Analysis. Ryan Burke, Alec Piñero, Max Coleman, Adam Mohan, Max Sapuppo, Francesca Augustin, Alan A Aragon, Darren G Candow, Scott C Forbes, Paul Swinton, Brad J Schoenfeld. Nutrients (2023)
Effects of Creatine Monohydrate on Endurance Performance in a Trained Population: A Systematic Review and Meta-analysis. Julen Fernández-Landa, Asier Santibañez-Gutierrez, Nikola Todorovic, Valdemar Stajer, Sergej M Ostojic. Sports Med (2023)
Effectiveness of Creatine in Metabolic Performance: A Systematic Review and Meta-Analysis. Arturo P Jaramillo, Luisa Jaramillo, Javier Castells, Andres Beltran, Neyla Garzon Mora, Sol Torres, Gabriela Carolina Barberan Parraga, Maria P Vallejo, Yurianna Santos. Cureus (2023)
Short-Term Creatine Supplementation and Repeated Sprint Ability-A Systematic Review and Meta-Analysis. Mark Glaister, Lauren Rhodes. Int J Sport Nutr Exerc Metab (2022)
Efficacy of Alternative Forms of Creatine Supplementation on Improving Performance and Body Composition in Healthy Subjects: A Systematic Review. Carly Fazio, Craig L Elder, Margaret M Harris. J Strength Cond Res (2022)
The Paradoxical Effect of Creatine Monohydrate on Muscle Damage Markers: A Systematic Review and Meta-Analysis. Kenji Doma, Akhilesh Kumar Ramachandran, Daniel Boullosa & Jonathan Connor. Sports Med (2022)
Interaction Between Caffeine and Creatine When Used as Concurrent Ergogenic Supplements: A Systematic Review. Sara Elosegui, Jaime López-Seoane, María Martínez-Ferrán, Helios Pareja-Galeano. Int J Sport Nutr Exerc Metab (2022)
Effects of creatine and caffeine ingestion in combination on exercise performance: A systematic review. Alisson H Marinho, Jaqueline S Gonçalves, Palloma K Araújo, Adriano E Lima-Silva, Thays Ataide-Silva, Gustavo G de Araujo. Crit Rev Food Sci Nutr (2021)
Creatine supplementation and VO2 max: a systematic review and meta-analysis. Damien Gras, Charlotte Lanhers, Reza Bagheri, Fred Dutheil. Crit Rev Food Sci Nutr (2021)
The Effect of Creatine Supplementation on Markers of Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis of Human Intervention Trials. Northeast B, Clifford T. Int J Sport Nutr Exerc Metab (2021)
Benefits of Creatine Supplementation for Vegetarians Compared to Omnivorous Athletes: A Systematic Review. Kaviani M, Shaw K, Chilibeck PD. Int J Environ Res Public Health (2020)
The Additive Effects of Creatine Supplementation and Exercise Training in an Aging Population: A Systematic Review of Randomized Controlled Trials. Stares A, Bains M. J Geriatr Phys Ther (2020)
Effect of the Combination of Creatine Monohydrate Plus HMB Supplementation on Sports Performance, Body Composition, Markers of Muscle Damage and Hormone Status: A Systematic Review. Fernández-Landa J, Calleja-González J, León-Guereño P, Caballero-García A, Córdova A, Mielgo-Ayuso J. Nutrients (2019)
Effects of Creatine Supplementation on Athletic Performance in Soccer Players: A Systematic Review and Meta-Analysis. Mielgo-Ayuso J, Calleja-Gonzalez J, Marqués-Jiménez D, Caballero-García A, Córdova A, Fernández-Lázaro D. Nutrients (2019)
Effects of creatine supplementation on cognitive function of healthy individuals: A systematic review of randomized controlled trials. Konstantinos I Avgerinos, Nikolaos Spyrou, Konstantinos I Bougioukas, Dimitrios Kapogiannis. Exp Gerontol (2018)
Creatine Supplementation and Upper Limb Strength Performance: A Systematic Review and Meta-Analysis. Lanhers C, Pereira B, Naughton G, Trousselard M, Lesage FX, Dutheil F. Sports Med (2017)
Creatine Supplementation and Lower Limb Strength Performance: A Systematic Review and Meta-Analyses. Lanhers C, Pereira B, Naughton G, Trousselard M, Lesage FX, Dutheil F. Sports Med (2015)
Creatine supplementation and aging musculoskeletal health. Candow DG, Chilibeck PD, Forbes SC. Endocrine (2014)
Creatine supplementation during resistance training in older adults-a meta-analysis. Devries MC, Phillips SM. Med Sci Sports Exerc (2014)
Effect of creatine supplementation on body composition and performance: a meta-analysis. Branch JD. Int J Sport Nutr Exerc Metab (2003)
Does oral creatine supplementation improve strength? A meta-analysis. Dempsey RL, Mazzone MF, Meurer LN. J Fam Pract (2002)
Creatine supplementation as an ergogenic aid for sports performance in highly trained athletes: a critical review. Mujika I, Padilla S. Int J Sports Med (1997)

You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.























Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.



Nitrate (NO3-) is a naturally occurring ion found in high amounts in leafy green veg, like spinach, and in beetroot, which is the food that has been popularised when talking “nitrate”. When we ingest nitrate or nitrate-containing foods, nitrate (NO3-) is converted to nitrite (NO2-). Nitrite is then absorbed in the intestine into the blood and metabolised to produce nitric oxide (NO) via several different enzymatic pathways. And, nitric oxide is important because it plays a major role in the regulation of vascular (it increases blood flow and vasodilation, which may enhance the delivery of oxygen and energy substrates to muscles) and metabolic (mitochondrial) function. But, it has a very short half-life in the body — when nitric oxide is produced, it acts rapidly and is used very quickly.
But, it’s little more complicated than than because we have no biological machinary to reduce nitrate (NO3-) to nitrite (NO2-) and rely on bacteria in our mouth for this part of the process (these bacteria use an enzyme called nitrate reductase to provide an electron and a proton to catalyse this reaction):
NO3- + e- + H+ → NO2- + H2O
Nitrate + an Electron + a Proton → Nitrite + Water
Interestingly, since it is the bacteria in your mouth that convert nitrate to nitrite allowing your biology to produce nitric oxide (NO), an alcohol-based mouthwash can prevent you producing nitrite (and, therefore, nitric oxide) after eating nitrate (see here & here)… Oh NO.
Nitrate + an Electron + a Proton → Nitrite + Water
Nitric oxide can be synthesised in our body from the amino acid, L-arginine, by nitric oxide synthase (NOS) enzymes. So, dietary intake of nitrate provides an additional source of nitric oxide on top of what our nitric oxide synthase pathways can produce. Since nitric oxide regulates blood flow and mitochondrial function, you can see why ingesting nitrate or nitrate-containing foods may be of interest to an athlete. But, nitrate (or beetroot) is certainly one of those compounds for which it is easy to head to PubMed and cherry-pick a paper showing that it is or is not beneficial for sports performance. So…
Does nitrate/beetroot juice improve performance — what do the systematic reviews say?

Effects on Strength and power:



Effects on Endurance:




All that said, there are also several nuances in this field:










To conclude…


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Full list of systematic reviews examining nitrate and beetroot for performance.
Here is the list of systematic reviews I have summarised above.
Effects of dietary inorganic nitrate on blood pressure during and post exercise: A systematic review and meta-analysis of randomized placebo-controlled trials. Benjamim et al. (2024) Free Radic Biol Med
Does Beetroot Supplementation Improve Performance in Combat Sports Athletes? A Systematic Review of Randomized Controlled Trials. Delleli et al. (2023) Nutrients
Limited Effects of Inorganic Nitrate Supplementation on Exercise Training Responses: A Systematic Review and Meta-analysis. Hogwood et al. (2023) Sports Med Open
Effects of Dietary Nitrate Supplementation on Back Squat and Bench Press Performance: A Systematic Review and Meta-Analysis. Tan et al. (2023) Nutrients
Effects of Beetroot-Based Supplements on Muscular Endurance and Strength in Healthy Male Individuals: A Systematic Review and Meta-Analysis. Evangelista et al. (2023) JANA
Effects of Dietary Nitrate Supplementation on Performance during Single and Repeated Bouts of Short-Duration High-Intensity Exercise: A Systematic Review and Meta-Analysis of Randomised Controlled Trials. Alsharif et al. (2023) Antioxidants
Factors that Moderate the Effect of Nitrate Ingestion on Exercise Performance in Adults: A Systematic Review with Meta-Analyses and Meta-Regressions. Silva et al. (2022) Adv Nutr
Dietary Inorganic Nitrate as an Ergogenic Aid: An Expert Consensus Derived via the Modified Delphi Technique. Shannon et al. (2022) Sports Med
The Effect of Dietary Nitrate on the Contractile Properties of Human Skeletal Muscle: A Systematic Review and Meta-Analysis. Ozcan Esen, Nick Dobbin, Michael J Callaghan. J Am Nutr Assoc (2022)
The Effects of Dietary Nitrate Supplementation on Explosive Exercise Performance: A Systematic Review. Rachel Tan,Leire Cano, Ángel Lago-Rodríguez and Raúl Domínguez. Int J Environ Res Public Health (2022)
The Effect of Beetroot Ingestion on High-Intensity Interval Training: A Systematic Review and Meta-Analysis. Tak Hiong Wong, Alexiaa Sim, Stephen F Burns. Nutrients (2021)
Effect of food sources of nitrate, polyphenols, L-arginine and L-citrulline on endurance exercise performance: a systematic review and meta-analysis of randomised controlled trials. Noah M. A. d’Unienville, Henry T. Blake, Alison M. Coates, Alison M. Hill, Maximillian J. Nelson & Jonathan D. Buckley. J Int Soc Sports Nutr (2021)
Effect of dietary nitrate on human muscle power: a systematic review and individual participant data meta-analysis. Coggan AR, Baranauskas MN, Hinrichs RJ, Liu Z, Carter SJ. J Int Soc Sports Nutr (2021)
Effects of Beetroot Supplementation on Recovery After Exercise-Induced Muscle Damage: A Systematic Review. Rojano-Ortega D, Peña Amaro J, Berral-Aguilar AJ, Berral-de la Rosa FJ. Sports Health (2021)
The effects of dietary nitrate supplementation on endurance exercise performance and cardiorespiratory measures in healthy adults: a systematic review and meta-analysis. Gao C, Gupta S, Adli T, Hou W, Coolsaet R, Hayes A, Kim K, Pandey A, Gordon J, Chahil G, Belley-Cote EP, Whitlock RP. J Int Soc Sports Nutr (2021)
The Effect of Nitrate-Rich Beetroot Juice on Markers of Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis of Human Intervention Trials. Jones L, Bailey SJ, Rowland SN, Alsharif N, Shannon OM, Clifford T. < J Diet Suppl (2021)
Effect of dietary nitrate ingestion on muscular performance: a systematic review and meta-analysis of randomized controlled trials. Alvares TS, Oliveira GV, Volino-Souza M, Conte-Junior CA, Murias JM. Crit Rev Food Sci Nutr (2021)
Ergogenic potential of foods for performance and recovery: a new alternative in sports supplementation? A systematic review. Costa MS, Toscano LT, Toscano LLT, Luna VR, Torres RA, Silva JA, Silva AS. Crit Rev Food Sci Nutr (2020)
The Effect of Dietary Nitrate Supplementation on Isokinetic Torque in Adults: A Systematic Review and Meta-Analysis.. Lago-Rodríguez Á, Domínguez R, Ramos-Álvarez JJ, Tobal FM, Jodra P, Tan R, Bailey SJ. Nutrients (2020)
Ergogenic Effect of Nitrate Supplementation: A Systematic Review and Meta-analysis. Senefeld JW, Wiggins CC, Regimbal RJ, Dominelli PB, Baker SE, Joyner MJ. Med Sci Sports Exerc (2020)
Nutritional Ergogenic Aids in Racquet Sports: A Systematic Review. Vicente-Salar N, Santos-Sánchez G, Roche E. Nutrients (2020)
Effects of Dietary Nitrates on Time Trial Performance in Athletes with Different Training Status: Systematic Review. Hlinský T, Kumstát M, Vajda P. Nutrients (2020)
Effects of diet interventions, dietary supplements, and performance-enhancing substances on the performance of CrossFit-trained individuals: A systematic review of clinical studies. Dos Santos Quaresma MVL, Guazzelli Marques C, Nakamoto FP. Nutrition (2021)
Effects of Dietary Nitrate Supplementation on Weightlifting Exercise Performance in Healthy Adults: A Systematic Review. San Juan AF, Dominguez R, Lago-Rodríguez Á, Montoya JJ, Tan R, Bailey SJ. Nutriients (2020)
Effectiveness of beetroot juice derived nitrates supplementation on fatigue resistance during repeated-sprints: a systematic review. Rojas-Valverde D, Montoya-Rodríguez J, Azofeifa-Mora C, Sanchez-Urena B. Crit Rev Food Sci Nutr (2020)
Influence of Nitrate Supplementation on Endurance Cyclic Sports Performance: A Systematic Review. Lorenzo Calvo J, Alorda-Capo F, Pareja-Galeano H, Jiménez SL. Nutrients (2020)
Nutritional Strategies to Optimize Performance and Recovery in Rowing Athletes. Kim J, Kim EK. Nutrients (2020)
The Effect of Nitrate Supplementation on Exercise Tolerance and Performance: A Systematic Review and Meta-Analysis. Van De Walle GP, Vukovich MD. J Strength Cond Res (2018)
Nitrate supplementation improves physical performance specifically in non-athletes during prolonged open-ended tests: a systematic review and meta-analysis. Campos HO, Drummond LR, Rodrigues QT, Machado FSM, Pires W, Wanner SP, Coimbra CC. Br J Nutr (2018)
Performance and Health Benefits of Dietary Nitrate Supplementation in Older Adults: A Systematic Review. Stanaway L, Rutherfurd-Markwick K, Page R, Ali A. Nutrients (2017)
The Effect of Dietary Nitrate Supplementation on Endurance Exercise Performance in Healthy Adults: A Systematic Review and Meta-Analysis. McMahon NF, Leveritt MD, Pavey TG. Sports Med (2017)
Effects of Beetroot Juice Supplementation on Cardiorespiratory Endurance in Athletes. A Systematic Review. Domínguez R, Cuenca E, Maté-Muñoz JL, García-Fernández P, Serra-Paya N, Estevan MC, Herreros PV, Garnacho-Castaño MV. Nutrients (2017)
The effect of nitrate supplementation on exercise performance in healthy individuals: a systematic review and meta-analysis. Hoon MW, Johnson NA, Chapman PG, Burke LM. Int J Sport Nutr Exerc Metab (2013)


You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.



































Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.



Some amino acids are coded by our genes, some are used to build proteins; others are not. Citrulline is an amino acid that is not coded by our genes and is not a protein building block but it is a “nonessential” amino acid (i.e. our body can synthesise it and we don’t need to consume it). Citrulline is an intermediate metabolite of the urea cycle produced in the mitochondria of the liver (see here for description of urea cycle and a diagram here). Citrulline is also synthesised from arginine by the enzyme, nitric oxide synthase, during nitric oxide (NO) production.
2 L-arginine + 3 NADPH + 3 H+ + 4 O2 ⇌ 2 L-citrulline + 2 nitric oxide + 4 H2O + 3 NADP+
Although our bodies naturally produce citrulline, consuming citrulline or citrulline-containing foods increases our citrulline levels. Citrulline is found in high amounts in watermelon, therefore citrulline-containing supplements include watermelon juice but also pure L-citrulline and citrulline malate. Malate is an intermediate metabolite of the tricarboxylic acid (TCA) cycle (a process that helps you produce ATP in the mitochondria). Therefore, supplement Lords believe malate will increase ATP production. Whether this is true is currently unknown and the effect of citrulline malate vs. L-citrulline is also not known.
In the context of exercise, the mechanistic effects of citrulline are not well understood. Based on cell studies, animal studies, and some human data, citrulline is thought to increase levels of nitric oxide (NO), a molecule that regulates mitochondrial and vascular function (increased blood flow and vasodilation to enhance the delivery of oxygen) with rapid but very short-lived effects. Meanwhile, due to its role in the urea cycle, citrulline may also improve the clearance of ammonia (which can accumulate in muscle during intense exercise and cause fatigue). Whether such potential mechanisms extrapolate to an improvement in performance is why I am writing this. So…
Does Citrulline (or watermelon juice or citrulline malate) improve performance — what do the systematic reviews say?














To conclude…


This tool is free. Please help keep it alive by buying me a beer:
Want free info like this in your inbox? Sign up here:
Full list of systematic reviews examining citrulline (malate) and watermelon for performance.
Here is the list of systematic reviews I have summarised above.
Effects of citrulline on endurance performance in young healthy adults: a systematic review and meta-analysis. Harnden et al. (2023) J Int Soc Sports Nutr
Effects of Citrulline Supplementation on Different Aerobic Exercise Outcomes: A Systematic Review and Meta-Analysis. Viribay et al. (2022) Nutrients
Effects of Citrulline Malate Supplementation on Muscle Strength in Resistance-Trained Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Aguiar et al. (2022) J Diet Suppl
Effect of food sources of nitrate, polyphenols, L-arginine and L-citrulline on endurance exercise performance: a systematic review and meta-analysis of randomised controlled trials. Noah M. A. d’Unienville, Henry T. Blake, Alison M. Coates, Alison M. Hill, Maximillian J. Nelson & Jonathan D. Buckley. J Int Soc Sports Nutr (2021)
Acute Effect of Citrulline Malate on Repetition Performance During Strength Training: A Systematic Review and Meta-Analysis. Vårvik FT, Bjørnsen T, Gonzalez AM. Int J Sport Nutr Exerc Metab (2021)
Nutritional Ergogenic Aids in Racquet Sports: A Systematic Review. Vicente-Salar N, Santos-Sánchez G, Roche E. Nutrients (2020)
Effects of Citrulline Supplementation on Exercise Performance in Humans: A Review of the Current Literature. Gonzalez AM, Trexler ET. J Strength Cond Res (2020)
Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis. Rhim HC, Kim SJ, Park J, Jang KM. J Sport Health Sci (2020)
Effects of Citrulline alone or combined with exercise on muscle mass, muscle strength, and physical performance among older adults: a systematic review. Aubertin-Leheudre M, Buckinx F. Curr Opin Clin Nutr Metab Care (2020)
Acute Effects of Citrulline Supplementation on High-Intensity Strength and Power Performance: A Systematic Review and Meta-Analysis. Trexler ET, Persky AM, Ryan ED, Schwartz TA, Stoner L, Smith-Ryan AE. Sports Med (2019)


You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.












Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.



Proteins in our body are in a constant state of flux — they form and degrade, over and over. Consequently, there is a minimum daily dietary protein intake that is required to maintain normal function, which includes maintaining muscle mass. When we exercise, the rate at which muscle proteins form and breakdown increases, and following exercise, especially strength exercise, there is an “anabolic” window of opportunity during which we can eat protein to provide a supply of amino acids to help swing the protein synthesis/breakdown equilibrium in favour of more synthesis. You can go deep on these concepts at veohtu.com/protein, veohtu.com/postexercisenutrition, and veohtu.com/carbohydrateplusprotein.
The proteins in your body include enzymes, peptide hormones, neurotransmitters, and structural proteins, and they are made up of “building blocks” called amino acids. But some amino acids are not used to build proteins, possessing other physiological functions (including metabolic, immunological, neurological, etc). Some amino acids are coded by our genes; others are not. Some amino acids are synthesised in our body from other metabolites; others are not. Amino acids that we cannot synthesise and/or cannot synthesise quick enough to meet our basic daily demands are called “essential” amino acids. For these, we need a dietary source.
In humans, there are 9 “essential” amino acids — phenylalanine, threonine, tryptophan, methionine, leucine, isoleucine, valine, lysine, and histidine. These 9 include leucine, isoleucine, and valine, which are known as branched-chain amino acids (BCAAs). BCAAs are unique because they are both used to build proteins and have direct physiological effects. For example, leucine can act as a signal to increase muscle protein synthesis after a meal (see a systematic review on this topic here). Because BCAAs are “essential” amino acids, we need to eat BCAAs in our diet to maintain optimal function. But this is no problem... Omnivorous folks who eat meat can easily obtain all essential amino acids in adequate quantities. Folks who follow a plant-based diet can also easily obtain all essential amino acids in adequate quantities so long as they eat a variety of plants. You can read all about this at veohtu.com/protein.
Since BCAAs have several direct physiological functions and since leucine can promote muscle protein synthesis, BCAA and leucine supplements have been popularised by solid marketing to become widespread. But…
Do BCAAs (or leucine) improve performance — what do the systematic reviews say?









And, don’t forget that whole foods can easily meets your needs…


To conclude…


This tool is free. Please help keep it alive by buying me a beer:
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Full list of systematic reviews examining BCAAs and leucine for performance.
Here is the list of systematic reviews I have summarised above.
Attenuating Muscle Damage Biomarkers and Muscle Soreness After an Exercise-Induced Muscle Damage with Branched-Chain Amino Acid (BCAA) Supplementation: A Systematic Review and Meta-analysis with Meta-regression. FirstAuthor et al. (2024) Sports Med Open
International Society of Sports Nutrition Position Stand: Effects of essential amino acid supplementation on exercise and performance. Ferrando et al. (2023) J Int Soc Sports Nutr
Association of postprandial postexercise muscle protein synthesis rates with dietary leucine: A systematic review. Wilkinson et al. (2023) Physiol Rep
The use of BCAA to decrease delayed-onset muscle soreness after a single bout of exercise: a systematic review and meta-analysis. Martim Gomes Weber, Silas Seolin Dias, Tarlyson Regioli de Angelis, Eduardo Vignoto Fernandes, Andrea Gomes Bernardes, Vinicius Flavio Milanez, Eduardo Inocente Jussiani, Solange de Paula Ramos. Amino acids (2021)
Intake of branched chain amino acids favors post-exercise muscle recovery and may improve muscle function: optimal dosage regimens and consumption conditions. Alejandra Arroyo-Cerezo, Isabel Cerrillo, Ángeles Ortega, María-Soledad Fernández-Pachón. J Sports Med Phys Fitness (2021)
Does Branched-Chain Amino Acids (BCAAs) Supplementation Attenuate Muscle Damage Markers and Soreness after Resistance Exercise in Trained Males? A Meta-Analysis of Randomized Controlled Trials. Chutimon Khemtong, Chia-Hua Kuo, Chih-Yen Chen, Salvador J Jaime, Giancarlo Condello. Nutrients (2021)
The effect of branched-chain amino acid on muscle damage markers and performance following strenuous exercise: a systematic review and meta-analysis. Kenji Doma, Utkarsh Singh, Daniel Boullosa, Jonathan Douglas Connor. Appl Physiol Nutr Metab (2021)
Nutritional interventions to improve muscle mass, muscle strength, and physical performance in older people: an umbrella review of systematic reviews and meta-analyses. Gielen E, Beckwée D, Delaere A, De Breucker S, Vandewoude M, Bautmans I; Sarcopenia Guidelines Development Group of the Belgian Society of Gerontology and Geriatrics (BSGG). Nutr Rev (2021)
Effect of Branched-Chain Amino Acid Supplementation on Muscle Soreness following Exercise: A Meta-Analysis. Fedewa MV, Spencer SO, Williams TD, Becker ZE, Fuqua CA. Int J Vitam Nutr Res (2019)
Branched-chain amino acid supplementation and exercise-induced muscle damage in exercise recovery: A meta-analysis of randomized clinical trials. Rahimi MH, Shab-Bidar S, Mollahosseini M, Djafarian K. Nutrition (2017)
Effects of branched amino acids in endurance sports: a review. (SPANISH) Salinas-García ME, Martínez-Sanz JM, Urdampilleta A, Mielgo-Ayuso J, Norte Navarro A, Ortiz-Moncada R. Nutr Hosp (2014)

You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.












Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.



β-hydroxy β-methylbutyrate (HMB) is part of the carboxylic acid family of organic compounds that circulates in micromolar (μM) concentrations in the blood. It is found in muscle, can cross the blood-brain barrier and is excreted in the urine. Our body can synthesise HMB from the branched-chain amino acid (BCAA), leucine. But HMB is also found in trace amounts in several foods, including asparagus, avocados, cauliflower, and grapefruit.
The biology of HMB has been studied for a long ole time and much is known. For example, it has been known since the 1990s that HMB supplementation during resistance training directly affects muscle function and it was discovered more recently that HMB simultaneously promotes muscle protein synthesis and prevents muscle protein breakdown. Therefore, HMB supplementation has the potential to increase muscle mass and, for this reason, HMB is often added to high-protein medical foods used to treat muscle wasting (cachexia) in diseases like cancer and AIDS. But…
Does HMB improve performance — what do the systematic reviews say?











To conclude…


This tool is free. Please help keep it alive by buying me a beer:
Want free info like this in your inbox? Sign up here:
Full list of systematic reviews examining HMB for performance.
Here is the list of systematic reviews I have summarised above.
Effects of HMB on Endurance Performance in a Healthy Population: A Systematic Review and Meta-Analysis. Fernández-Landa et al. (2024) J Strength Cond Res
An umbrella review of systematic reviews of β‐hydroxy‐β‐methyl butyrate supplementation in ageing and clinical practice. Stuart M. Phillips, Kyle J. Lau, Alysha C. D'Souza, Everson A. Nunes. J Cachexia Sarcopenia Muscle (2022)
Does HMB Enhance Body Composition in Athletes? A Systematic Review and Meta-analysis. Brett M Holland, Brandon M Roberts, James W Krieger, Brad J Schoenfeld. J Strength Cond Res (2022)
Effects of oral administration of β-hydroxy β-methylbutyrate on lean body mass in older adults: a systematic review and meta-analysis. Lin Z, Zhao Y, Chen Q. Eur Geriatr Med (2021)
Nutritional Strategies to Optimize Performance and Recovery in Rowing Athletes. Kim J, Kim EK. Nutrients (2020)
Supplementation with the Leucine Metabolite β-hydroxy-β-methylbutyrate (HMB) does not Improve Resistance Exercise-Induced Changes in Body Composition or Strength in Young Subjects: A Systematic Review and Meta-Analysis.
Jakubowski JS, Nunes EA, Teixeira FJ, Vescio V, Morton RW, Banfield L, Phillips SM. Nutrients (2020)
Does HMB Enhance Body Composition in Athletes? A Systematic Review and Meta-analysis. Holland BM, Roberts BM, Krieger JW, Schoenfeld BJ. J Strength Cond Res (2019)
Health Benefits of β-Hydroxy-β-Methylbutyrate (HMB) Supplementation in Addition to Physical Exercise in Older Adults: A Systematic Review with Meta-Analysis. Courel-Ibáñez J, Vetrovsky T, Dadova K, Pallarés JG, Steffl M. Nutrients (2019)
The Effects of Beta-Hydroxy-Beta-Methylbutyrate Supplementation on Recovery Following Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis. Rahimi MH, Mohammadi H, Eshaghi H, Askari G, Miraghajani M. J Am Coll Nutr (2018)
Effects of beta-hydroxy-beta-methylbutyrate supplementation on strength and body composition in trained and competitive athletes: A meta-analysis of randomized controlled trials. Sanchez-Martinez J, Santos-Lozano A, Garcia-Hermoso A, Sadarangani KP, Cristi-Montero C. J Sci Med Sport (2018)
β-hydroxy-β-methylbutyrate free acid supplementation may improve recovery and muscle adaptations after resistance training: a systematic review. Silva VR, Belozo FL, Micheletti TO, Conrado M, Stout JR, Pimentel GD, Gonzalez AM. Nutr Res (2017)
Beta-hydroxy-beta-methylbutyrate supplementation in health and disease: a systematic review of randomized trials. Molfino A, Gioia G, Rossi Fanelli F, Muscaritoli M. Amino Acids (2013)
Effects of beta-hydroxy-beta-methylbutyrate supplementation during resistance training on strength, body composition, and muscle damage in trained and untrained young men: a meta-analysis. Rowlands DS, Thomson JS. J Strength Cond Res (2009)
Effect of dietary supplements on lean mass and strength gains with resistance exercise: a meta-analysis. Nissen SL, Sharp RL. J Appl Physiol (2003)

You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.















Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.



Some amino acids are coded by our genes, some are used to build proteins; others are not. Beta-alanine is an amino acid but, unlike its familiar sibling L-alpha-alanine, it is not used as a “building block” for protein synthesis. Instead, beta-alanine can act as a neurotransmitter by binding to GABA receptors and NMDA receptors. But, beta-alanine is also a biochemical precursor to carnosine (aka β-alanyl-L-histidine), which is a dipeptide of beta-alanine and another amino acid called histidine. And, carnosine is an intracellular buffer — it helps regulate hydrogen ion (H+) concentrations (aka pH) in your cells.
β-alanine + histidine + ATP ⇌ carnosine + ADP + Pi
Carnosine is a particularly important pH buffer in muscle cells, and orally-ingested beta-alanine can increase muscle carnosine levels (see Rezende et al. 2020). Therefore, beta-alanine has become a popular sports supplement. So…
Does beta-alanine (or carnosine or anserine) improve performance — what do the systematic reviews say?













To conclude…


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Full list of systematic reviews examining beta-alanine, carnosine, and anserine for performance.
Here is the list of systematic reviews I have summarised above.
β-Alanine Supplementation in Combat Sports: Evaluation of Sports Performance, Perception, and Anthropometric Parameters and Biochemical Markers-A Systematic Review of Clinical Trials. Fernández-Lázaro et al. (2023) Nutrients
Effects of beta-alanine supplementation on body composition: a GRADE-assessed systematic review and meta-analysis. Damoon Ashtary-Larky, Reza Bagheri, Matin Ghanavati, Omid Asbaghi, Alexei Wong, Jeffrey R Stout, Katsuhiko Suzuki. J Int Soc Sports Nutr (2022)
Effect of β-alanine and sodium bicarbonate co-supplementation on the body's buffering capacity and sports performance: A systematic review. Laura Gilsanz, Jaime López-Seoane, Sergio L Jiménez, Helios Pareja-Galeano. Crit Rev Food Sci Nutr (2021)
Individual Participant Data Meta-Analysis Provides No Evidence of Intervention Response Variation in Individuals Supplementing With Beta-Alanine. Gabriel Perri Esteves, Paul Swinton, Craig Sale, Ruth M James, Guilherme Giannini Artioli, Hamilton Roschel, Bruno Gualano, Bryan Saunders, Eimear Dolan. Int J Sport Nutr Exerc Metab (2021)
Effects of beta-alanine supplementation on Yo-Yo test performance: A meta-analysis. Jozo Grgic. Clin Nutr ESPEN (2021)
The Muscle Carnosine Response to Beta-Alanine Supplementation: A Systematic Review With Bayesian Individual and Aggregate Data E-Max Model and Meta-Analysis. Rezende et al. (2020) Front Physiol
Effects of Beta-Alanine Supplementation on Physical Performance in Aerobic-Anaerobic Transition Zones: A Systematic Review and Meta-Analysis. Ojeda et al. (2020) Nutrients
Effects of Beta-Alanine Supplementation on Physical Performance in Aerobic–Anaerobic Transition Zones: A Systematic Review and Meta-Analysis. Álvaro Huerta Ojeda, Camila Tapia Cerda, María Fernanda Poblete Salvatierra, Guillermo Barahona-Fuentes, and Carlos Jorquera Aguilera. Nutrients (2020)
Effect of Supplements on Endurance Exercise in the Older Population: Systematic Review. Martínez-Rodríguez A, Cuestas-Calero BJ, Hernández-García M, Martíez-Olcina M, Vicente-Martínez M, Rubio-Arias JÁ. Int J Environ Res Public Health (2020)
Nutritional Strategies to Optimize Performanceand Recovery in Rowing Athletes. Kim J, Kim EK. Nutrients (2020)
The Impact of Preconditioning Strategies Designed to Improve 2000-m Rowing Ergometer Performance in Trained Rowers: A Systematic Review and Meta-Analysis. Turnes T, Cruz RSO, Caputo F, De Aguiar RA. Int J Sports Physiol Perform (2019)
β-alanine supplementation to improve exercise capacity and performance: a systematic review and meta-analysis. Saunders B, Elliott-Sale K, Artioli GG, Swinton PA, Dolan E, Roschel H, Sale C, Gualano B. Br J Sports Med (2017)
Effects of beta-alanine supplementation on performance and muscle fatigue in athletes and non-athletes of different sports: a systematic review. Berti Zanella P, Donner Alves F, Guerini de Souza C. J Sports Med Phys Fitness (2017)
The effects of beta-alanine supplementation on performance: a systematic review of the literature. Quesnele JJ, Laframboise MA, Wong JJ, Kim P, Wells GD. Int J Sport Nutr Exerc Metab (2014)
Effects of β-alanine supplementation on exercise performance: a meta-analysis. Hobson RM, Saunders B, Ball G, Harris RC, Sale C. Amino Acids (2012)

You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.















Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.



Sodium bicarbonate (NaHCO3) is a salt made up of a sodium cation (Na+) and a bicarbonate anion (HCO3-) that is commonly used in cooking. In fact, sodium bicarbonate probably sits in your kitchen cupboard hidden among the ingredients of baking soda (aka bicarbonate of soda).

2 NaHCO3 → Na2CO3 + CO2 + H2O
Note: this reaction does not occur in your body.
But, I’m headed off-piste… To stay on topic, sodium bicarbonate is also the active ingredient in antacid drugs because it neutralizes stomach acid and subsequently relieves heartburn and indigestion. When sodium bicarbonate encounters acid (hydrogen ions, H+; or hydrogen chloride, HCl, in the stomach), it reacts in an acid-base reaction, again releasing sodium ions (Na+; or sodium chloride, NaCl, in the stomach) and carbon dioxide:
Note: this reaction does not occur in your body.
NaHCO3 + H+ → Na+ + CO2 + H2O
Now you’re probably starting to see how bicarbonate might work in the context of exercise…
Your body has an in-built bicarbonate buffering system that helps keep pH under control. This is important because various processes in your body operate optimally at a specific pH. Your stomach, for example, operates optimally at an “acidic” pH, which would destroy the epithelial cell lining of your gastrointestinal system (the gastric mucosa) if the bicarbonate buffering system wasn’t present to protect the cells from stomach acid. Meanwhile, your blood is maintained at a “neutral” pH because of the bicarbonate buffering system that helps minimise the fluctuations in carbon dioxide (CO2) and hydrogen ions (H+) resulting from energy metabolism. If, for example, physiological conditions cause a rise in your blood CO2 and hydrogen ion (H+) concentrations (a drop in pH), your bicarbonate buffering system buffers the H+ ions and helps transport CO2 to the lungs so you can puff it out into the air.
CO2 + H2O ⇌ H2CO3 ⇌ HCO3- + H+
Carbon dioxide + Water ⇌ Carbonic acid ⇌ Bicarbonate + Hydrogen ion
Like all buffers, the bicarbonate buffering system in your body consists of a weak acid (carbonic acid, H2CO3) and its conjugate base (bicarbonate, HCO3--) that helps neutralise any excess acid or base that appears. During high-intensity, highly-glycolytic exercise — that is when your need for ATP must be met by rapid glucose metabolism — you produce carbon dioxide (CO2) at a high rate and hydrogen ions (H+) can accumulate possibly causing intramuscular acidosis, which is one (of many) theorised causes of fatigue. Therefore, a buffering supplement has the potential to help your in-house bicarbonate buffering system overcome the large disturbance in the force. Consequently, sodium bicarbonate has become a popular supplement. And, it ain’t new — famous exercise physiologists like David Bruce (D.B.) Dill in the Harvard Fatigue Laboratory were studying the effects of sodium bicarbonate in runners over 100-years ago! But…
Carbon dioxide + Water ⇌ Carbonic acid ⇌ Bicarbonate + Hydrogen ion
Does sodium bicarbonate improve performance — what do the systematic reviews say?














To conclude…


This tool is free. Please help keep it alive by buying me a beer:
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Full list of systematic reviews examining sodium bicarbonate for performance.
Here is the list of systematic reviews I have summarised above.
Acute effects of sodium bicarbonate ingestion on cycling time-trial performance: A systematic review and meta-analysis of randomized controlled trials. Lopes-Silva et al. (2023) Eur J Sport Sci
Effects of Ketone Monoester and Bicarbonate Co-Ingestion on Cycling Performance in WorldTour Cyclists. Ramos-Campo et al. (2023) Int J Sport Nutr Exerc Metab
Effects of Sodium Bicarbonate Ingestion on Measures of Wingate Test Performance: A Meta-Analysis. Jozo Grgic. J Am Nutr Assoc (2022)
Effect of sodium bicarbonate supplementation on two different performance indicators in sports: a systematic review with meta-analysis. Lino et al. (2021) Phys Act Nutr
Effect of sodium bicarbonate contribution on energy metabolism during exercise: a systematic review and meta-analysis. Calvo et al. (2021) J Int Soc Sports Nutr
Sodium bicarbonate supplementation and the female athlete: A brief commentary with small scale systematic review and meta-analysis. Saunders B, Oliveira LF, Dolan E, Durkalec-Michalski K, McNaughton L, Artioli GG, Swinton PA. Eur J Sport Sci (2021)
Effect of β-alanine and sodium bicarbonate co-supplementation on the body's buffering capacity and sports performance: A systematic review. Laura Gilsanz, Jaime López-Seoane, Sergio L Jiménez, Helios Pareja-Galeano. Crit Rev Food Sci Nutr (2021)
Extracellular Buffering Supplements to Improve Exercise Capacity and Performance: A Comprehensive Systematic Review and Meta-analysis. Luana Farias de Oliveira, Eimear Dolan, Paul A Swinton, Krzysztof Durkalec-Michalski, Guilherme G Artioli, Lars R McNaughton, Bryan Saunders. Sports Med (2021).
Effects of sodium bicarbonate supplementation on exercise performance: an umbrella review.
Jozo Grgic, Ivana Grgic, Juan Del Coso, Brad J Schoenfeld, Zeljko Pedisic. J Int Soc Sports Nutr (2021)
Effect of sodium bicarbonate supplementation on two different performance indicators in sports: a systematic review with meta-analysis. Lino RS, Lagares LS, Oliveira CVC, Queiroz CO, Pinto LLT, Almeida LAB, Bonfim ES, Santos CPCD. Phys Act Nutr (2021)
Effects of diet interventions, dietary supplements, and performance-enhancing substances on the performance of CrossFit-trained individuals: A systematic review of clinical studies. Dos Santos Quaresma MVL, Guazzelli Marques C, Nakamoto FP. Nutrition (2021)
A Systematic Review and Meta-analysis on Sodium Bicarbonate Administration and Equine Running Performance: Is it Time to Stop Horsing Around With Baking Soda? Denham J, Hulme A. J Equine Vet Sci (2020)
Effects of Sodium Bicarbonate Supplementation on Muscular Strength and Endurance: A Systematic Review and Meta-analysis. Grgic J, Rodriguez RF, Garofolini A, Saunders B, Bishop DJ, Schoenfeld BJ, Pedisic Z. Sports Med (2020)
Isolated effects of caffeine and sodium bicarbonate ingestion on performance in the Yo-Yo test: A systematic review and meta-analysis. Grgic J, Garofolini A, Pickering C, Duncan MJ, Tinsley GM, Del Coso J. J Sci Med Sport (2020)
The Impact of Preconditioning Strategies Designed to Improve 2000-m Rowing Ergometer Performance in Trained Rowers: A Systematic Review and Meta-Analysis. Turnes T, Cruz RSO, Caputo F, De Aguiar RA. Int J Sports Physiol Perform (2019)
The Impact of Sodium Bicarbonate on Performance in Response to Exercise Duration in Athletes: A Systematic Review. Hadzic M, Eckstein ML, Schugardt M. J Sports Sci Med (2019)
Acute and chronic effect of sodium bicarbonate ingestion on Wingate test performance: a systematic review and meta-analysis. Lopes-Silva JP, Reale R, Franchini E. J Sports Sci (2019)
β-alanine supplementation to improve exercise capacity and performance: a systematic review and meta-analysis. Saunders B, Elliott-Sale K, Artioli GG, Swinton PA, Dolan E, Roschel H, Sale C, Gualano B. Br J Sports Med (2017)
A systematic review of the efficacy of ergogenic aids for improving running performance. Schubert MM, Astorino TA. J Strength Cond Res (2013)
Practical recommendations for coaches and athletes: a meta-analysis of sodium bicarbonate use for athletic performance. Peart DJ, Siegler JC, Vince RV. J Strength Cond Res (2012)
Effects of acute alkalosis and acidosis on performance: a meta-analysis. Carr AJ, Hopkins WG, Gore CJ. Sports Med (2011)
Effects of sodium bicarbonate ingestion on anaerobic performance: a meta-analytic review. Matson LG, Tran ZV. Int J Sport Nutr (1993) .

You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.























Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.



Carnitine gained some notoriety because it was one of the “supplements” that played a starring role in the Alberto Salazar-associated Mo Farah debacle. In the world of medicine, carnitine is sometimes used in patients with peripheral artery disease to help treat a symptom called “intermittent claudication” — jargon for muscle pain/soreness/aching during exertion, particularly in the calf muscles during walking. This symptom usually subsides when the patient stops walking and it occurs because of impairments in blood flow and energy metabolism (muscle carnitine deficiency, which reduces fat metabolism). Several systematic reviews (see here, here, here, & here) show that oral or intravenous administration of either L-carnitine or propionyl-L-carnitine (a derivative) is a useful add-on therapy for treating intermittent claudication and improving walking capacity in folks with peripheral artery disease. Sounds exciting… but, first up, what is carnitine?
Carnitine is an amino acid predominantly found in muscle tissue. Some amino acids are coded by our genes, some are used to build proteins; others are not. Carnitine is not coded by our genes and is not used to build proteins; instead, our body can synthesise it from other amino acids (methionine and lysine). But, meat-eating folks also obtain a large proportion of carnitine in their diet. But, what does it do?
At rest and during low to moderate-intensity exercise, our body predominantly “burns” fatty acids to produce energy (ATP). To do so, fatty acids must be transported into the mitochondria of our cells so they can be “oxidised” (aka metabolised). Carnitine is of great importance because it helps “shuttle” fatty acid molecules into your mitochondria (via the carnitine palmitoyltransferase system) so they can be metabolised (via beta-oxidation) to produce lots of ATP (chemical energy). So, during exercise, the carnitine palmitoyltransferase system acts as a gateway to allow fat “burning”.
Supplementing with L-carnitine or propionyl-L-carnitine increases intracellular carnitine concentrations in muscle. Furthermore, propionyl-L-carnitine (a carnitine derivative) has a higher affinity for muscular carnitine transferase enzyme and produces propionyl-coA in the mitochondria, which is synthesised to succinyl-CoA, entering the Krebs cycle to produce energy. Double win.
Since L-carnitine or propionyl-L-carnitine supplementation can increase muscle levels of carnitine and since doing so can improve walking capacity in folks with peripheral artery disease, the big question is…
Does L-Carnitine (or propionyl-L-carnitine) improve performance — what do the systematic reviews say?











Or



To conclude…

This tool is free. Please help keep it alive by buying me a beer:
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Full list of systematic reviews examining (propionyl) L-carnitine for performance.
Here is the list of systematic reviews I have summarised above.
Clinical Effects of L-Carnitine Supplementation on Physical Performance in Healthy Subjects, the Key to Success in Rehabilitation: A Systematic Review and Meta-Analysis from the Rehabilitation Point of View. Vecchio et al. (2021) J Funct Morphol Kinesio
Effect of Acute and Chronic Oral l-Carnitine Supplementation on Exercise Performance Based on the Exercise Intensity: A Systematic Review. Mielgo-Ayuso et al. (2021) Nutrients


You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.




Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.



Ketones are naturally occurring metabolites produced in your body that include acetate, acetoacetate, and β-hydroxybutyrate (or 3-hydroxybutyrate). They normally circulate in the blood in trace amounts (less than 0.5 millimoles/litre, 0.5 mM) but levels can rise under certain conditions. Ketosis is a metabolic state characterised by elevated concentrations (0.5 to 3 mM) of ketone bodies (acetate, acetoacetate, & β-hydroxybutyrate) in your blood (and urine) caused by depletion of carbohydrate stores (low glycogen) in the body. This typically happens during starvation, prolonged exercise, or a prolonged fast (not eating any calories for at least 12 hours), or in folks who eat a very low carbohydrate diet (less than 50 grams of carbs per day). This would be called “physiological ketosis” because ketone levels are elevated but not enough to cause acidosis. This is a little different from ketoacidosis, a pathophysiological state that can occur in patients with diabetes who develop prolonged hypoglycemia (low blood glucose) and blood ketones of up to 10 mM or more — ketoacidosis requires urgent medical care while physiological ketosis does not.
When elevated, ketones provide an additional fuel source to support your brain’s energy needs when glucose availability is low (depleted glycogen + low blood glucose). Under such conditions, your liver metabolises triglycerides/fatty acids, releasing ketones into the blood, which are then transported into the brain. But, besides the physiological/pathophysiological events that cause ketosis, ingesting ketones also raises blood ketone concentrations causing ketosis without the need for restricting the intake of calories or carbohydrates (see here & here). This is typically achieved by consuming a ketone ester (e.g. (R)-3-hydroxybutyl (R)-3-hydroxybutyrate) or a ketone precursor (e.g. R-1,3-butanediol). Ketone supplementation has gathered momentum and systematic reviews show that a single dose of ketones can decrease blood glucose concentrations, showing its potential for diabetes treatment. There are also studies showing how ketone supplementation may affect appetite and cognitive function in humans, but more high-quality studies are needed before definitive conclusions can be made.
The first published exercise study using ketone supplementation found increased fat oxidation during exercise and improved time-trial performance even in the presence of high carbohydrate availability (normal muscle glycogen levels and during-exercise carbohydrate ingestion). Consequently, popular science media is awash with the benefits of ketones for athletic performance and several companies sell ketone-containing products. The most heavily marketed ketone supplement is the “drinkable ketone” from HVMN, which contains a ketone precursor (R-1,3-butanediol) that is converted to β-hydroxybutyrate (a ketone) in the body. If you follow pro cycling, you will hear a lot about this product because they sponsor a large number of the pro teams. But sexy marketing is not part of the scientific method. So…
Do ketones improve performance — what do the systematic reviews say?










To conclude…


This tool is free. Please help keep it alive by buying me a beer:
Want free info like this in your inbox? Sign up here:
Full list of systematic reviews examining ketones for performance.
Here is the list of systematic reviews I have summarised above.
Acute Ingestion of Ketone Monoesters and Precursors Do Not Enhance Endurance Exercise Performance: A Systematic Review and Meta-Analysis. Emma Brooks, Gilles Lamothe, Taniya S Nagpal, Pascal Imbeault, Kristi Adamo, Jameel Kara, Éric Doucet. Int J Sport Nutr Exerc Metab (2022).
Utility of Ketone Supplementation to Enhance Physical Performance: A Systematic Review. Margolis LM, O'Fallon KS. Adv Nutr (2020).
Acute Ketone Supplementation and Exercise Performance: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Valenzuela PL, Morales JS, Castillo-García A, Lucia A. Int J Sports Physiol Perform (2020).

You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.




Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.



CBD (cannabidiol) and THC (tetrahydrocannabinol) belong to a class of chemicals called, cannabinoids. THC is the main cannabinoid that provides the relaxing “high” plus a bunch of other side effects (paranoia, sleepiness, short-term memory loss, dizziness, confusion, reduced coordination, slurred speech) when smoking/eating/vaping marijuana (or when eating “edibles” containing isolated THC). On the other hand, CBD is isolated from dried, crushed cannabis plants and does not have any psychoactive properties but is alleged to relieve pain, improve sleep, and reduce inflammation.
Cannabinoids have been used to develop some drugs. For example, CBD is the active ingredient in Epidiolex, which is prescribed to treat seizures in patients with rare forms of epilepsy; while THC is the active ingredient in Nabiximols/Sativex, which is used to treat pain in patients with multiple sclerosis. Beyond that, “medical marijuana” is now prescribed in some countries, while some folks recreationally use THC-containing “edibles” or smoke marijuana to relieve anxiety and pain caused by chronic disease. However, despite being a prescription drug in some countries, the overall effect and risk/benefit balance of marijuana is debated. All that said, business is booming for CBD and THC. And, the theoretical benefits of cannabinoids in sports are frequently reported. Plus, the world has gone wild for CBD oils and tinctures and rubs with abundant claims of greatest for athletes. So, the important question…
Do CBD or THC or cannabis improve performance — what do the systematic reviews say?



Effects of THC and cannabis:



Effects of CBD:





To conclude…


This tool is free. Please help keep it alive by buying me a beer:
Want free info like this in your inbox? Sign up here:
Full list of systematic reviews examining CBD, THC, and cannabis for performance.
Here is the list of systematic reviews I have summarised above.
Does acute cannabidiol (CBD) use impair performance? A meta-analysis and comparison with placebo and delta-9-tetrahydrocannabinol (THC). Lo et al. (2024) Neuropsychopharmacology
Chronic cannabis consumption and physical exercise performance in healthy adults: a systematic review. Andrew Kramer, Justin Sinclair, Lara Sharpe, Jerome Sarris. J Cannabis Res (2022)
Acute effects of cannabis consumption on exercise performance: a systematic and umbrella review. Charron J, Carey V, Marcotte L'heureux V, Roy P, Comtois AS, Ferland PM. J Sports Med Phys Fitness (2021).
Cannabis Use and Sport: A Systematic Review. Shgufta Docter, Moin Khan, Chetan Gohal, Bheeshma Ravi, Mohit Bhandari, Rajiv Gandhi, Timothy Leroux. Sports Health (2020).
Chronic cannabis consumption and physical exercise performance in healthy adults: a systematic review. Kramer A, Sinclair J, Sharpe L, Sarris J. J Cannabis Res (2020).
Cannabis: Exercise performance and sport. A systematic review. Kennedy MC. J Sci Med Sport (2017).


You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.








Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.



Fish oils are rich in DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), which are long-chain polyunsaturated n–3 (ω-3) fatty acids (aka omega-3 fatty acids) found in oily fish like salmon, herring, mackerel, and tuna, and in predatory fish that eat oily fish (e.g. swordfish, shark, tuna). DHA and EPA are also found in algae and in high amounts in flax seeds, chia seeds, hemp seeds, and walnuts.
In our body, DHA and EPA have a number of roles. EPA primarily acts as a precursor in the synthesis of prostaglandins and leukotrienes, which are molecules involved in inflammation and immune function. Meanwhile, DHA primary acts as a structural component in the cerebral cortex, skin, and retina. But, while both EPA and DHA are important fatty acids, neither are classified as “essential” fatty acids because our body can synthesise them in adequate amounts to maintain normal function, but only if you have an adequate dietary source of another omega-3 fatty acid, called alpha-linolenic acid (aka ALA, one of the two essential fatty acids in humans along with linoleic acid). Alpha-linolenic acid is found in chia seeds and flax seeds but, in humans, the synthesis efficiency of alpha-linolenic acid to EPA and DHA is rather poor, hence the dietary recommendation to consume foods containing ALA, DHA and EPA.
Because of the abundance of omega-3 fatty acids in several foods, it is likely that you’ve been getting your daily fix of omega-3s for years. And, because we are under the perilous dietary fallacies of our elders, you might have been subjected to that spoonful of cod liver oil* your mum used to trick you into eating every morning as a kid. (*Note: cod liver oil is not only rich in DHA and EPA but also vitamins A and E; and, it tastes like sh*t — I hated my mum 40 years ago.) But, since many folks’ diet is subpar and since many folks probably don’t eat fish or seeds, it is also likely that many folks aren’t getting any DHA, EPA, or alpha-linolenic acid (ALA) in their diet. Therefore, omega-3s and fish oils have become very popular dietary supplements and supplementation may be necessary for people whose diet lacks foods containing DHA, EPA, and ALA. Beyond that, it is very difficult to ignore brand marketing campaigns regularly plugging fish oil products for athlete recovery and/or performance — on that note, the important question is…
Do omega-3s (DHA and EPA) or fish oils improve performance or recovery — what do the systematic reviews say?
Please note that this summary is about exercise performance and/or recovery, not disease risk, prevention, or treatment. If you want to go deep on the effects of omega-3s (DHA and EPA) or fish oils on general health, please check out examine.com/supplements/fish-oil/ because Examine.com go deep on dietary supplements from a health perspective and I consider it a carefully-researched and trusted source. (NOTE: For full disclosure, I started working as a researcher for Examine in October 2022.)



But…



But…







To conclude…





This tool is free. Please help keep it alive by buying me a beer:
Want free info like this in your inbox? Sign up here:
Full list of systematic reviews examining omega-3s (DHA and EPA) and fish oils for performance and recovery.
Here is the list of systematic reviews I have summarised above.
Omega-3 Fatty Acid Supplementation on Post-Exercise Inflammation, Muscle Damage, Oxidative Response, and Sports Performance in Physically Healthy Adults-A Systematic Review of Randomized Controlled Trials. Fernández-Lázaro et al. (2024) Nutrients
Effects of Omega-3 fatty acids supplementation and resistance training on skeletal muscle. Uchida et al. (2024) Clin Nutr ESPEN
Effects of Omega-3 Fatty Acid Supplementation on Skeletal Muscle Mass and Strength in Adults: A Systematic Review. Moon et al. (2023) Clin Nutr Res
Effects of Omega-3 Supplementation Alone and Combined with Resistance Exercise on Skeletal Muscle in Older Adults: A Systematic Review and Meta-Analysis. Stephen M Cornish Dean M Cordingley, Keely A Shaw, Scott C Forbes, Taylor Leonhardt, Ainsley Bristol, Darren G Candow, Philip D Chilibeck. Nutrients (2022)
The effect of long chain omega-3 polyunsaturated fatty acids on muscle mass and function in sarcopenia: A scoping systematic review and meta-analysis. Julia K Bird, Barbara Troesch, Ines Warnke, Philip C Calder. Clin Nutr ESPEN (2021)
Effect of omega-3 fatty acids supplementation on indirect blood markers of exercise-induced muscle damage: Systematic review and meta-analysis of randomized controlled trials. Gao Xin, Hesam Eshaghi. Food Sci Nutr (2021)
N-3 PUFA as an ergogenic supplement modulating muscle hypertrophy and strength: a systematic review. López-Seoane J, Martinez-Ferran M, Romero-Morales C, Pareja-Galeano H. Crit Rev Food Sci Nutr (2021).
The effect of fish oil supplementation on the promotion and preservation of lean body mass, strength, and recovery from physiological stress in young, healthy adults: a systematic review. Heileson JL, Funderburk LK. Nutr Rev (2020).
Are There Benefits from the Use of Fish Oil Supplements in Athletes? A Systematic Review. Lewis NA, Daniels D, Calder PC, Castell LM, Pedlar CR. Adv Nutr (2020).
Omega-3 Polyunsaturated Fatty Acid Supplementation for Reducing Muscle Soreness after Eccentric Exercise: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Zheng-Tao Lv, Jin-Ming Zhang, Wen-Tao Zh. Biomed Res Int (2020)
Response to exercise in older adults who take supplements of antioxidants and/or omega-3 polyunsaturated fatty acids: A systematic review. Rosario Pastor, Josep A Tur. Biochem Pharmacol (2020)

You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.












Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.



Vitamin D is a fat-soluble vitamin that primarily regulates calcium (and phosphate and magnesium) metabolism to facilitate bone growth and maintain bone health. Vitamin D deficiency causes bone irregularities, which in the extreme can cause rickets (impaired bone growth) in children and osteomalacia (soft bones & weak muscles) and osteoporosis (low bone density & fractures) in adults. Our skin cells can synthesise cholecalciferol (aka vitamin D3) when our skin is exposed to sunlight (UV-B radiation), but we also obtain vitamin D3 in our diet from foods like egg yolks, liver, oily fish (salmon, mackerel, sardines), and cod liver oil, as well as from foods that have been “fortified” with vitamin D3 (like some breakfast cereals and milk).
But vitamin D synthesis and metabolism are super complex and confusing. When synthesised in the skin or eaten, cholecalciferol (vitamin D3) travels in the blood to the liver where it is “hydroxylated” (a hydroxyl group, —OH, is added) to produce a prohormone called calcifediol (aka 25-hydroxyvitamin D aka 25(OH)D). Calcifediol then leaves the liver and travels in the blood to your kidneys, where it is further “hydroxylated” to produce the active “hormonal” form of vitamin D, called calcitriol (1,25(OH)2D). Calcitriol is released by the kidney into the blood and then acts like a hormone, binding to vitamin D receptors on various tissues in the body to cause its effects. Furthermore, calcitriol is also produced in some immune cells where it plays a role in innate immunity.
Phew!
The prevalence of vitamin D deficiency is widely studied and, likely due to poor dietary habits and low exposure to direct sunlight, is actually pretty high — ~20% in Australia, ~68% across 5 South-East Asian countries, ~40% in the USA, ~34% in Scotland, and ~18% across Africa, etc. But, it is important to note that prevalence estimates massively vary by season.
Due to the high prevalence of vitamin D deficiency, vitamin D is commonly prescribed as a dietary supplement to bring bodily levels of cholecalciferol (aka vitamin D3) back up to normal. However, vitamin D supplements are also freely available over the counter, which creates a problem because vitamin D is fat-soluble and, therefore, is stored in the body and can be toxic when supplemented in high amounts. Interestingly, the 2013-14 NHANES (National Health and Nutrition Examination Survey) survey found that 18% of American adults exceeded 1000 IU (international units) of supplemental vitamin D per day, which is more than twice the US RDA (recommended daily amount), and that 3% took more than 4000 IU per day, which exceeds the upper tolerable limit and, therefore, increases the risk of adverse effects. The 1999-2000 NHANES survey found that just 0.3% and 0.1% of the population exceeded 1000 or 4000 IUs daily, indicating that intentional (and excessive) vitamin D supplementation has increased dramatically.
Vitamin D has many physiological roles and is essential for maintaining health. Systematic reviews and meta-analyses have examined the association of blood concentrations of the vitamin D prohormone, calcifediol (or 25(OH)D) with various health outcomes — low 25(OH)D is associated with higher all-cause and cardiovascular-related risk of dying (aka mortality; see here & here), and a greater risk of severe infections (sepsis), cardiovascular disease, type 2 diabetes (see here & here), gestational diabetes, and dementia. But, associations do not prove that low vitamin D is causal in disease nor do they prove that vitamin supplementation will prevent or treat disease. Fortunately, systematic reviews and meta-analyses have determined the effect of vitamin D supplementation on disease…
Vitamin D supplementation doesn’t lower the risk of death from any cause (aka all-cause mortality) in the general population (see here, here, & here) nor does it lower the risk of cardiovascular disease (CVD) or CVD end-points (myocardial infarction, stroke, CVD mortality). But, Vitamin D supplementation may lower cancer-related risk of death, all-cause mortality in elderly folks, risk of diabetes in folks with prediabetes (see here, here, & here), and may help improve blood glucose control in patients with type 2 diabetes (see here & here).
NOTE: At this time, the effect of vitamin D supplementation on cognitive decline in dementia has not been systematically reviewed.
To summarise the above, vitamin D deficiency is associated with disease risk and supplementation may reduce the risk for some conditions. But, importantly, several of the meta-analyses found that the effects of vitamin D supplementation were only (or most) pronounced in folks who had vitamin D deficiency (blood 25-(OH)D <30 ng/ml) — i.e. supplementation was simply bringing vitamin D back to healthy levels.
Vitamin D has become a very popular dietary supplement and supplementation can be necessary for people who have a vitamin D deficiency (caused by a lack of daily sunlight, a dietary lack of foods containing vitamin D, or an irregularity of vitamin D metabolism). As of 2020, Public Health England, the health authority in the cloudy and sunlight-deficient UK, now recommends that all people who don’t obtain sufficient vitamin D in their diet should take a vitamin D supplement in the autumn and winter months (when sunlight is nonexistent, which is a normal day in the life of a Brit). However, the optimal vitamin D supplementation dose and the optimal dietary vitamin D intake are currently uncertain (see here). All that said, certain populations — children and adolescents aged 1 to 18 years, adults aged 75 years and older, pregnant women, people with intestinal disorders, etc. — have an increased risk of vitamin D deficiency (see here), so if you suspect you have a vitamin D deficiency, consult your doctor who can assess your vitamin D status by ordering a blood test for 25(OH)D (25-hydroxyvitamin D). A plasma concentration of <30 ng/ml indicates deficiency and your doctor may prescribe you a vitamin D supplement based on your results.
NOTE: you will see many names assigned to a vitamin D blood test — a 25-OH vitamin D blood test, cholecalciferol (vitamin D3) test, ergocalciferol (vitamin D2) test, calcidiol test, vitamin D2 test, or vitamin D3 test — which all assess a different aspect of vitamin D metabolism.
Since vitamin D receptors and vitamin D-related metabolites have been discovered in skeletal muscle and given that vitamin D regulates calcium metabolism and calcium is essential for muscle contraction, it is not absurd to hypothesise a role for vitamin D in muscle function. Indeed, a 2013 systematic review found that the blood concentration of 25(OH)D (25-hydroxyvitamin D, aka calcifediol) is associated with muscle strength. Since vitamin D deficiency is not rare, it is also not absurd to hypothesise that vitamin D supplementation may help performance — no doubt you have noticed the outbreak of brand marketing campaigns regularly plugging vitamin D products for athlete recovery and/or performance. So, the important question is…
Does vitamin D improve performance or recovery — what do the systematic reviews say?
Please note that this summary is about exercise performance and/or recovery, not disease risk, prevention, or treatment. If you want to go deep on the effects of vitamin D on general health, please check out examine.com/supplements/vitamin-d because Examine.com go deep on dietary supplements from a health perspective and I consider it a carefully-researched and trusted source. (NOTE: For full disclosure, I started working as a researcher for Examine in October 2022.)




But…









To conclude…


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Full list of systematic reviews examining vitamin D for performance and recovery.
Here is the list of systematic reviews I have summarised above.
Effects of vitamin D supplementation on maximal strength and power in athletes: a systematic review and meta-analysis of randomized controlled trials. Sist et al. (2023) Front Nutr
Effects of vitamin D supplementation on muscle function and recovery after exercise-induced muscle damage: A systematic review. Rojano-Ortega et al. (2023) J Hum Nutr Diet
Vitamin D Supplementation Improves Handgrip Strength in Postmenopausal Women: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Jia-Li Zhang, Christina Chui-Wa Poon, Man-Sau Wong, Wen-Xiong Li, Yi-Xun Guo, Yan Zhang. Front Endocrinol (2022)
Effect of vitamin D monotherapy on indices of sarcopenia in community-dwelling older adults: a systematic review and meta-analysis. Konstantinos Prokopidis, Panagiotis Giannos, Konstantinos Katsikas Triantafyllidis, Konstantinos S Kechagias, Jakub Mesinovic, Oliver C Witard, David Scott. J Cachexia Sarcopenia Muscle (2022)
Effects of Vitamin D in Post-Exercise Muscle Recovery. A Systematic Review and Meta-Analysis. Hugo J Bello, Alberto Caballero-García, Daniel Pérez-Valdecantos, Enrique Roche, David C Noriega, Alfredo Córdova-Martínez. Nutrients (2021)
The Optimal Strategy of Vitamin D for Sarcopenia: A Network Meta-Analysis of Randomized Controlled Trials. Shih-Hao Cheng, Kee-Hsin Chen, Chiehfeng Chen, Woei-Chyn Chu, Yi-No Kang. Nutrients (2021)
The effects of vitamin D supplementation on muscle strength and mobility in postmenopausal women: a systematic review and meta-analysis of randomised controlled trials. M Abshirini, H Mozaffari, H Kord-Varkaneh, M Omidian, M C Kruger. J Hum Nutr Diet (2020)
Effect of vitamin D supplementation on upper and lower limb muscle strength and muscle power in athletes: A meta-analysis. Lin Zhang, Minghui Quan, Zhen-Bo Cao. PLoS One (2019)
The effect of combined resistance exercise training and vitamin D3 supplementation on musculoskeletal health and function in older adults: a systematic review and meta-analysis. Antoniak AE, Greig CA. BMJ Open (2017)
Vitamin D supplementation and its influence on muscle strength and mobility in community-dwelling older persons: a systematic review and meta-analysis. H Rosendahl-Riise, U Spielau, A H Ranhoff, O A Gudbrandsen, J Dierkes. J Hum Nutr Diet (2017) — This article has a correction at ncbi.nlm.nih.gov/pmc/articles/PMC6885933/.
Effects of Vitamin D Supplementation on Serum 25-Hydroxyvitamin D Concentrations and Physical Performance in Athletes: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Forough Farrokhyar, Gayathri Sivakumar, Katey Savage, Alex Koziarz, Sahab Jamshidi, Olufemi R Ayeni, Devin Peterson, Mohit Bhandari. Sports Med (2017)
Effects of Vitamin D Supplementation on Muscle Strength in Athletes: A Systematic Review. Chien-Ming Chiang, Ahmed Ismaeel, Rachel B Griffis, Suzy Weems. J Strength Cond Res (2017)
A Systematic Review of the Role of Vitamin D on Neuromuscular Remodelling Following Exercise and Injury. Minshull C, Biant LC, Ralston SH, Gleeson N. Calcif Tissue Int (2016)
Effects of vitamin D supplementation on upper and lower body muscle strength levels in healthy individuals. A systematic review with meta-analysis. Peter B Tomlinson, Corey Joseph, Manuela Angioi. J Sci Med Sport (2015)
The effects of vitamin D on skeletal muscle strength, muscle mass, and muscle power: a systematic review and meta-analysis of randomized controlled trials. Charlotte Beaudart, Fanny Buckinx, Véronique Rabenda, Sophie Gillain, Etienne Cavalier, Justine Slomian, Jean Petermans, Jean-Yves Reginster, Olivier Bruyère. J Clin Endocrinol Metab (2014)
Effect of vitamin D supplementation on muscle strength, gait and balance in older adults: a systematic review and meta-analysis. Muir SW, Montero-Odasso M. J Am Geriatr Soc (2011)
Effect of vitamin D supplementation on muscle strength: a systematic review and meta-analysis. K A Stockton, K Mengersen, J D Paratz, D Kandiah, K L Bennell. Osteoporos Int (2011)
Vitamin D-related changes in physical performance: a systematic review. C Annweiler, A M Schott, G Berrut, B Fantino, O Beauchet. Journal (2009)
Vitamin D and cognitive performance in adults: a systematic review. C Annweiler, G Allali, P Allain, S Bridenbaugh, A-M Schott, R W Kressig, O Beauchet. Eur J Neurol (2009)
Effects of vitamin D supplementation on strength, physical performance, and falls in older persons: a systematic review. Nancy K. Latham, Craig S. Anderson, Ian R. Reid. J Am Geriatr Soc (2003)

You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.





















Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.


In the 90s, I moshed my socks off to Brian Molko’s melodic voice at many a Placebo gig. He taught me one thing: placebos rock! Dad jokes aside, a placebo is sometimes used in clinical trials and usually takes the form of a sugar pill, a saline (salt water) injection (like saline), or sham (fake) surgery (where the surgeon opens you up, has some lunch, stitches you back up, and pretends they did a procedure on you). Theoretically, a placebo is supposed to have no effect on whatever variable of interest you are studying.
In a randomised controlled trial, there is a treatment group and a control group. Sometimes, the control group is given something that resembles the treatment to prevent participants from knowing which group they are in — this something is called a “placebo” and we’d call this type of trial a placebo-controlled clinical trial. If the variable of interest improves in the placebo-controlled group we might think that the placebo has had an effect. But, to make that conclusion, we would need an additional non-placebo control group to know whether the placebo has improved the variable of interest more than doing nothing at all — it could be that the disease naturally improves with time. When studies have a placebo-controlled group and a non-placebo control group, if the change in the variable of interest in the placebo group is larger than the change in the non-placebo group, we can conclude that there has been a placebo effect (and Brian Molko can sing about it). On the flip side, if the variable of interest worsens in the placebo-controlled group (and more so than in the non-placebo group), we conclude that there has been a nocebo effect (i.e. a negative or detrimental placebo effect).
Imagine this scenario:

If you are right, then this supplement could be called a placebo and your race win could be called a placebo effect. But, because you had a positive expectation of a performance-enhancing effect, the effect of the placebo could also be called a belief effect. But, a positive expectation of an effect is not always required for a placebo effect and having a positive expectation of an effect can even enhance the placebo effect. The important thing to learn is that while your experiences shape your beliefs, your experiences (i.e. you won after taking a supplement) must be combined with data (your training had been great, you’d set PBs all season, and were in the shape of your life) to accurately inform your belief. The other important thing to learn is that “you are the only person responsible for what goes in your body” — never take candy from
Now, that was just hypothetical — you’re probably wondering, does the placebo effect exist?
Several systematic reviews have found evidence for the placebo effect in a range of diseases in studies where participants are blinded to whether they are receiving a placebo or the real treatment. A couple of recent systematic reviews (see here & here) also find evidence for the placebo effect on a range of diseases when an “open-label” placebo (participants know they’re receiving a placebo) is compared to a non-placebo (no treatment) intervention, with summary effect sizes of 0.88 (a large effect; 95% confidence interval 0.62 to 1.14) and 0.72 (a moderate effect; 95%CI 0.39 to 1.05).
Woah!
But… These findings should be interpreted with caution because, in longitudinal studies (when the variable of interest is measured before and after several days/weeks/months/years), as I said earlier, the disease might naturally improve with time without real treatment. (Putting that in the context of exercise, your performance might improve while training with a supplement but it might also improve with training alone.) Furthermore, most studies do not have non-placebo control group. Plus, there are only a few small “open label” trials and participants weren’t blinded to the placebo vs. no treatment groups and, in many cases, participants received “positive messages” in addition to the open-label placebos before being asked about their feelings of pain or discomfort. E.g. “This will make you feel better.” ... … “How are you feeling?”.
Sometimes doctors prescribe placebos (without the patient’s knowledge) instead of therapeutic drugs to help “treat” a condition. As is probably obvious, from an ethical stance, placebos are a touchy subject — patients have a right to know what they’re receiving rather than being “deceived”. Furthermore, since the “belief effect” (the extent to which a person believes the treatment will work) can also influence the effectiveness of interventions, it could be argued that instead of deceptively-prescribing placebos (in place of therapeutic drugs), doctors could use the placebo effect and/or the belief effect to enhance the therapeutic effect of a drug — if a patient believes the treatment will help them, perhaps they’ll be more motivated to adhere to it. But, I’m going a little off-piste and away from exercise performance.
In research, it is very difficult for scientists to get “deception” studies approved by ethical review boards. But there are some fun examples. In a 2015 study from Ramzy et al., trained 10 km runners received no treatment or daily injections of “OxyRBX”, which they were told had the same effects as EPO (a red blood cell-boosting hormone that improves endurance performance). Before and after 7-days of treatment/no treatment, runners completed a 3 km race. On average, athletes in the OxyRBX group improved their 3 km time by 9.73 seconds (95%CI 5.14 to 14.33 seconds) whereas untreated athletes ran 1.82 s faster (95%CI 2.77 s slower to 6.41 s faster; group-change comparison P=0.02). OxyRBX-treated runners also reported less physical effort, increased motivation, and improved recovery. This is an example of a placebo effect, probably caused by a belief effect.
That’s kinda fun but now consider this thought experiment:

Does the placebo effect improve recovery and/or performance — what do the systematic reviews say?




Therefore…




To conclude…




This tool is free. Please help keep it alive by buying me a beer:
Want free info like this in your inbox? Sign up here:
Full list of systematic reviews examining the placebo effect for recovery and performance.
Here is the list of systematic reviews I have summarised above.
Nonplacebo Controls to Determine the Magnitude of Ergogenic Interventions: A Systematic Review and Meta-analysis. Felipe Miguel Marticorena, Arthur Carvalho, Luana Farias DE Oliveira, Eimear Dolan, Bruno Gualano, Paul Swinton, Bryan Saunders. Med Sci Sports Exerc (2021)
The Placebo and Nocebo effect on sports performance: A systematic review. Philip Hurst, Lieke Schipof-Godart, Attila Szabo, John Raglin, Florentina Hettinga, Bart Roelands, Andrew Lane, Abby Foad, Damian Coleman, Chris Beedie. Eur J Sports Sci (2020)
Consensus statement on placebo effects in sports and exercise: The need for conceptual clarity, methodological rigour, and the elucidation of neurobiological mechanisms. Beedie et al. (2018) Eur J Sport Sci
Quantifying the placebo effect in psychological outcomes of exercise training: a meta-analysis of randomized trials. Jacob B Lindheimer, Patrick J O'Connor, Rod K Dishman. Sports Med (2015)

You are the only person responsible for what goes in your body.
Ignorance is not an excuse!
Stay educated. Be informed.





Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.


Position statements are written by a panel of experts (typically more than 10) chosen by the issuing society to grade the quality of evidence on a particular topic. The statements are typically peer-reviewed by several folks and go through several revisions before being published. Unlike other published reviews or original investigations, a position statement represents the journal’s (and the society that owns the journal) opinion — it is their position statement. A good position statement will use evidence from high-quality, large-scale, randomised controlled trials and, ideally, systematic reviews and meta-analyses, and then discuss the evidence in the context of practice.
There are several sports supplement-related position statements from the American College of Sports Medicine (ACSM), the International Olympic Committee (IOC), and the International Society for Sports Nutrition (ISSN):
ACSM —
Nutrition and Athletic Performance position statement. Travis Thomas, Kelly Erdman, & Louise Burke. Med Sci Sports Exerc (2016)
IOC —
Consensus statement: dietary supplements and the high-performance athlete. Ron Maughan and colleagues. Br J SportsMed (2018)
ISSN —
Exercise & sports nutrition position statement. Chad Kerksick and colleagues. J Int Soc Sports Nutr (2018). The ISSN have also published individual position statements on the use of caffeine, creatine, beta-alanine, and HMB (β-hydroxy β-methylbutyrate).

IOC —

ISSN —

Which supplements do the position statements say have a beneficial effect on performance?




This tool is free. Please help keep it alive by buying me a beer:
Want free info like this in your inbox? Sign up here:

Strengthen the fight for Clean Sport:
Consult WADA’s prohibited list.
Cross-check your meds against the Global DRO drug reference list.
Only choose supplements that have been independently tested by Informed Sport or LabDoor.






And remember:
Nail your daily nutrition habits first, layer specific sports nutrition on top of that, and then start to consider supplements.

Photo of pyramid by Eugene Tkachenko on Unsplash.


Thanks for using this tool. I am passionate about equality in access to free education. If you find value in my content, please help keep it alive by sharing it on social media and buying me a beer at buymeacoffee.com/thomas.solomon. For more knowledge, join me @veohtu on Twitter, Mastodon, Facebook, and Instagram, subscribe to my free email updates at veothu.com/subscribe, and check out my other Articles, Nerd Alerts, Free Training Tools, and my Train Smart Framework. To learn while you train, you can even listen to my articles by subscribing to the Veohtu podcast.
Disclaimer: I occasionally mention brands and products but it is important to know that I am not affiliated with, sponsored by, an ambassador for, or receiving advertisement royalties from any brands. I have conducted biomedical research for which I have received research money from publicly-funded national research councils and medical charities, and also from private companies, including Novo Nordisk Foundation, AstraZeneca, Amylin, A.P. Møller Foundation, and Augustinus Foundation. I’ve also consulted for Boost Treadmills and Gu Energy on their research and innovation grant applications and I’ve provided research and science writing services for Examine — some of my articles contain links to information provided by Examine but I do not receive any royalties or bonuses from those links. These companies had no control over the research design, data analysis, or publication outcomes of my work. Any recommendations I make are, and always will be, based on my own views and opinions shaped by the evidence available. My recommendations have never and will never be influenced by affiliations, sponsorships, advertisement royalties, etc. The information I provide is not medical advice. Before making any changes to your habits of daily living based on any information I provide, always ensure it is safe for you to do so and consult your doctor if you are unsure.
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About the author:
I am Thomas Solomon and I'm passionate about relaying accurate and clear scientific information to the masses to help folks meet their fitness and performance goals. I hold a BSc in Biochemistry and a PhD in Exercise Science, and am an ACSM-certified Exercise Physiologist and Personal Trainer, a VDOT-certified Distance running coach, and a Registered Nutritionist. Since 2002, I have conducted biomedical research in exercise and nutrition and have taught and led university courses in exercise physiology, nutrition, biochemistry, and molecular medicine. My work has been published in over 80 peer-reviewed medical journals publications and I have delivered more than 50 conference presentations & invited talks at universities and medical societies. I have coached and provided training plans for truck-loads of athletes, have competed at a high level in running, cycling, and obstacle course racing, and continue to run, ride, ski, hike, lift, and climb as much as my ageing body will allow. To stay on top of scientific developments, I consult for scientists, participate in journal clubs, peer-review papers for medical journals, and I invest every Friday in reading what new delights have spawned onto PubMed. In my spare time, I hunt for phenomenal mountain views to capture through the lens, boulder problems to solve, and new craft beers that send my gustatory system into a hullabaloo.
Copyright © Thomas Solomon. All rights reserved.
I am Thomas Solomon and I'm passionate about relaying accurate and clear scientific information to the masses to help folks meet their fitness and performance goals. I hold a BSc in Biochemistry and a PhD in Exercise Science, and am an ACSM-certified Exercise Physiologist and Personal Trainer, a VDOT-certified Distance running coach, and a Registered Nutritionist. Since 2002, I have conducted biomedical research in exercise and nutrition and have taught and led university courses in exercise physiology, nutrition, biochemistry, and molecular medicine. My work has been published in over 80 peer-reviewed medical journals publications and I have delivered more than 50 conference presentations & invited talks at universities and medical societies. I have coached and provided training plans for truck-loads of athletes, have competed at a high level in running, cycling, and obstacle course racing, and continue to run, ride, ski, hike, lift, and climb as much as my ageing body will allow. To stay on top of scientific developments, I consult for scientists, participate in journal clubs, peer-review papers for medical journals, and I invest every Friday in reading what new delights have spawned onto PubMed. In my spare time, I hunt for phenomenal mountain views to capture through the lens, boulder problems to solve, and new craft beers that send my gustatory system into a hullabaloo.
Copyright © Thomas Solomon. All rights reserved.