Beetroot nitrates are one of the few sports supplements that the International Olympic Committee assigns to the group with sufficient evidence of effectiveness. But what exactly has been proven, for whom, and how large is the effect? The editorial team analyzed the key studies and meta-analyses.
How the evidence base was built
The history of scientific interest in nitrates in sport began with an unexpected result. In 2007, the Swedish group of Larsen, Weitzberg, Lundberg, and Ekblom published a study in which taking sodium nitrate for three days reduced oxygen consumption during submaximal work on a cycle ergometer. For physiologists this was a sensation: it was believed that muscular efficiency was a quantity almost impossible to change through nutrition.
Already in 2009, the group of Andrew Jones from the University of Exeter (Bailey et al., 2009) reproduced this result, using beetroot juice instead of nitrate salt. They also showed that after several days of taking the juice, participants could withstand high-intensity exercise to exhaustion for longer. It was precisely this work that opened the way for commercial 'beetroot shots.'
Subsequently, the number of studies grew into the hundreds. Methodologically, this field has an important advantage: for a control, beetroot juice from which nitrate has been removed with an ion-exchange resin is used. The taste and color of such a placebo are identical, so a double-blind study here is relatively easy to implement, which increases confidence in the results.
At the same time, most studies had small samples - often 8-15 participants - and mostly involved young men. This should be kept in mind when transferring the conclusions to women, older people, or athletes of other disciplines.
What the meta-analyses say
Individual studies can produce random results, so it is important to look at generalizations. The meta-analysis by Hoon and colleagues (2013) showed that nitrates more noticeably improve results in 'to exhaustion' tests, whereas in time-trial tests, which are closer to real competition, the effect was small and not always statistically significant.
A later and larger meta-analysis by Senefeld and colleagues (2020), covering dozens of studies, confirmed the presence of a small but statistically significant ergogenic effect of nitrates. The authors also noted that the effect depended on the duration of exercise, the intake regimen, and the participants' level of training.
The consensus of the International Olympic Committee (Maughan et al., 2018) assigned nitrates to the short list of supplements with a sufficient evidence base for directly improving athletic performance. The authors of the consensus specifically emphasized that the typical performance gain is only a few percent and is most pronounced in exercise lasting up to about 40 minutes.
It is important to understand what 'a few percent' means in practice. For an amateur running 10 km it may be a difference of a minute, while for an elite athlete it is a few seconds, which also matters - but it is precisely in the elite that the effect is least predictable. So expectations of the supplement should be realistic.
| Study | Type | Main conclusion |
|---|---|---|
| Larsen et al., 2007 | RCT, sodium nitrate | Reduced oxygen cost of submaximal work |
| Bailey et al., 2009 | RCT, beetroot juice | Longer tolerance of high-intensity work |
| Wylie et al., 2013 | Dose dependence | Doses above ~8 mmol gave no additional benefit |
| Hoon et al., 2013 | Meta-analysis | Effect more noticeable in to-exhaustion tests than in time trials |
| Porcelli et al., 2015 | RCT, different training levels | Benefit decreases as aerobic fitness rises |
| Senefeld et al., 2020 | Meta-analysis | Small but statistically significant effect |
Dose dependence and duration of action
An important question for practice is how much nitrate is needed. The study by Wylie and colleagues (2013) compared different volumes of concentrated beetroot juice. The smallest dose (about 4 mmol of nitrate) raised the plasma nitrite level but had almost no effect on results. A dose of about 8 mmol improved performance, while doubling it to about 17 mmol gave no additional benefit.
The same study described the pharmacokinetics: the plasma nitrite concentration peaks approximately 2-3 hours after intake and remains elevated for several hours. This is precisely why in most protocols the juice is taken 2-3 hours before exercise.
As for the duration of intake, some studies suggest that several days of 'saturation' produce a more stable effect than a single intake. This especially applies to high-intensity and intermittent exercise, where adaptation of the muscle tissue itself is probably important (Jones et al., 2018).
We examine the practical details of dosing in detail in a separate article, but here it is important to emphasize: 'more' does not mean 'better,' and the dose-response curve fairly quickly reaches a plateau.
Who benefits and who does not
One of the most consistent patterns is the influence of training level. In the study by Porcelli and colleagues (2015), participants with lower aerobic fitness received a noticeable improvement, while in the well-trained the effect was minimal. A similar trend has been described in reviews by Jones (2014).
Probable explanations: elite-level athletes have a higher baseline level of nitrate and nitrite in plasma, more active endothelial NO synthase, a denser capillary network, and a higher percentage of slow muscle fibers, which nitrates, according to animal models, affect less. Nevertheless, individual 'responders' are found among the elite.
As for sports, the best-studied are cyclic disciplines - running, cycling, rowing, swimming. For team games with repeated sprints there are individual positive studies, but generalizations are so far less confident. For strength sports and bodybuilding there is not enough data to speak of real benefit.
For female athletes, as well as for elderly people, there is less data, and the conclusions here are so far preliminary. Interestingly, in older people nitrates are also studied in the context of functional endurance and vascular health, not just athletic performance.
- The greatest chance of feeling the effect is in amateurs and moderately trained people.
- Exercise lasting from a few minutes to about 40 minutes is the 'target zone.'
- Using mouthwashes and some medications can reduce the action of nitrates.
Study limitations and open questions
Despite the convincing overall picture, the evidence base has weak spots. First - the samples. The average study involved very few participants, so individual positive or negative results may be random. Meta-analyses partly solve this problem but do not eliminate the heterogeneity of protocols.
Second - sex. Most works were conducted on men, while data on women are limited. There are hypotheses that women have a higher baseline nitrite level and the response may differ, but there are no definitive conclusions yet.
Third - the gap between the laboratory and competition. Tests to exhaustion are very sensitive to changes but do not reproduce real race conditions. In time trials and field studies the effect is smaller.
Fourth - individual differences in oral microbiota, diet, and lifestyle. People who already eat a lot of green vegetables may get a smaller additional effect from the supplement. Personalizing nitrate intake is one of the directions of future research.
Editorial conclusions
Beetroot nitrates are among the few sports supplements with a solid evidence base recognized by the IOC. They can reduce the oxygen cost of work and increase tolerance to intense exercise.
However, the actual performance gain is small, most noticeable in amateurs and in exercise of moderate duration, while in elite athletes it may be minimal. The dose dependence quickly reaches a plateau, so excessive doses make no sense.
We also recommend reading our articles 'Beetroot nitrate: what it is and how it works,' 'How to take beetroot nitrate: dosage, timing, duration,' and 'Myths about beetroot nitrate.'
References
- Larsen FJ, Weitzberg E, Lundberg JO, Ekblom B. Effects of dietary nitrate on oxygen cost during exercise. Acta Physiol (Oxf). 2007;191(1):59–66.
- Bailey SJ, Winyard P, Vanhatalo A, et al. Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans. J Appl Physiol. 2009;107(4):1144–1155.
- Wylie LJ, Kelly J, Bailey SJ, et al. Beetroot juice and exercise: pharmacodynamic and dose-response relationships. J Appl Physiol. 2013;115(3):325–336.
- Hoon MW, Johnson NA, Chapman PG, Burke LM. The effect of nitrate supplementation on exercise performance in healthy individuals: a systematic review and meta-analysis. Int J Sport Nutr Exerc Metab. 2013;23(5):522–532.
- Porcelli S, Ramaglia M, Bellistri G, et al. Aerobic fitness affects the exercise performance responses to nitrate supplementation. Med Sci Sports Exerc. 2015;47(8):1643–1651.
- Senefeld JW, Wiggins CC, Regimbal RJ, et al. Ergogenic effect of nitrate supplementation: a systematic review and meta-analysis. Med Sci Sports Exerc. 2020;52(10):2250–2261.
- Jones AM, Thompson C, Wylie LJ, Vanhatalo A. Dietary nitrate and physical performance. Annu Rev Nutr. 2018;38:303–328.
- Maughan RJ, Burke LM, Dvorak J, et al. IOC consensus statement: dietary supplements and the high-performance athlete. Br J Sports Med. 2018;52(7):439–455.
Andriy Melnyk
A strength-sports coach and author of programs for beginner and intermediate levels. Writes about training planning.
