Performance nutrition
Beetroot juice for runners: does dietary nitrate actually work?
Beetroot juice is one of the very few legal supplements with genuine, repeatable evidence behind it. The science is real, the mechanism is elegant, and the catch is that the effect is smaller than the marketing suggests, especially if you are already fast.
Walk into any race expo and you will find a stall selling little purple shots that promise to make you faster. Most supplements that make that claim are wishful thinking. Beetroot juice is the rare exception that has stood up to laboratory testing. The active ingredient is not some exotic compound. It is plain inorganic nitrate, the same molecule found in spinach, rocket and chard.
This article explains how dietary nitrate works, what the research has actually measured, the dose and timing that the studies support, and the important reasons it may do very little for you if you are already a well trained runner.
The nitrate, nitrite and NO pathway
The story starts in your mouth. When you drink beetroot juice, the nitrate is absorbed, circulated in the blood, and then concentrated in your saliva. Bacteria living on the surface of your tongue reduce that nitrate to nitrite. You swallow the nitrite, and in the acidic, low oxygen conditions of the body it is converted further into nitric oxide, a signalling molecule that widens blood vessels and influences how efficiently your muscles use oxygen.
Jones (2014) summarised this nitrate to nitrite to nitric oxide pathway and its relevance to sport. The key point is that this route is independent of the classical oxygen dependent way your body makes nitric oxide, so it becomes especially useful when oxygen is in short supply, which is exactly what happens in hard running. Supplementing with nitrate raises plasma nitrite, lowers resting blood pressure, and reduces the oxygen cost of submaximal exercise.
That last effect is the one runners care about. If you can run a given pace while consuming less oxygen, you are, in a word, more economical. Running economy sits alongside VO2max as one of the central determinants of endurance performance.
What the research actually shows
The foundational experiment came from Bailey et al. (2009). Eight men drank 500 ml of beetroot juice a day for six days, and the oxygen cost of moderate intensity cycling fell by around 19 percent in the rate at which oxygen uptake rose, while tolerance to severe intensity exercise improved markedly. This was striking, because the oxygen cost of a given workload had previously been thought of as essentially fixed.
Lowering oxygen cost is interesting, but runners ultimately want a faster finish. Lansley et al. (2011) tested that directly. Club level cyclists who took roughly 6.2 mmol of nitrate about two and a half hours before a time trial improved their 4 km and 16.1 km performance by around 2.8 and 2.7 percent. Cermak, Gibala and van Loon (2012) found a similar picture in trained cyclists, where six days of concentrated beetroot juice providing about 8 mmol of nitrate per day reduced submaximal oxygen uptake and improved 10 km time trial performance.
A few percent may sound trivial, but over a race it is the difference between a personal best and an ordinary day. It is a similar order of effect to caffeine, the other supplement with solid evidence behind it, and the two work through entirely different mechanisms.
The dose that works
You do not need to guess at the amount. Wylie et al. (2013) mapped the dose to response relationship directly, giving 70, 140 or 280 ml of concentrated beetroot juice, supplying roughly 4.2, 8.4 and 16.8 mmol of nitrate. The 140 and 280 ml doses lowered the oxygen cost of moderate exercise and extended time to task failure, but the highest dose gave no extra benefit over the middle one.
The practical conclusion across the literature, reinforced by Senefeld et al. (2020), is that an effective dose is roughly 6 to 8 mmol of nitrate, with little to gain above about 8 to 12 mmol. In everyday terms that is around 500 ml of standard beetroot juice, or a single concentrated “shot” designed to deliver that amount.
Timing.
Plasma nitrite, the active intermediate, peaks roughly 2 to 3 hours after you drink the juice. Take an acute dose in that window before the start. For a larger effect you can also load with a daily dose for 3 to 6 days beforehand, finishing with a dose on race morning. Practise it in training first, because the high nitrate load can upset some stomachs.
The catch: it does less for fast runners
Here is the honest part the shot stalls tend to skip. The benefit of dietary nitrate is not uniform. It is smaller, and sometimes absent, in highly trained endurance athletes. Senefeld et al. (2020) pooled the evidence from dozens of studies and concluded that while nitrate improves performance on average, nearly 70 percent of individual studies found no statistically significant effect, and the response was blunted in the fittest participants.
Why would elite athletes respond less? The leading explanation is that they already have a highly developed nitric oxide system, dense capillary networks, and excellent muscle oxygenation, so there is simply less headroom for an external nitrate boost to improve. Beetroot juice tops up a system that is already near its ceiling in elite runners, but it can meaningfully lift a recreational runner whose baseline is further from that ceiling.
Do not use antibacterial mouthwash.
The whole pathway depends on the bacteria on your tongue converting nitrate to nitrite. Govoni et al. (2008) showed that an antibacterial mouthwash markedly attenuates the rise in plasma nitrite after a nitrate load, and other work links it to a loss of the blood pressure benefit. If you are supplementing for a race, skip antibacterial mouthwash for those days, and do not scrub your tongue too hard.
Juice, shots, or whole food?
Nitrate is not unique to beetroot. It is abundant in green leafy vegetables such as rocket, spinach and chard, and a generous salad of these can supply a nitrate dose comparable to a beetroot shot. For everyday health and a steady dietary nitrate intake, whole foods are an excellent and inexpensive source.
The advantage of juice and concentrated shots is precision. When you want to hit a known 6 to 8 mmol dose at a known time before a race, a labelled shot removes the guesswork that comes with a plate of greens. Many runners use whole foods day to day and reserve a concentrated shot for race day and key sessions.
One more practical note. Beetroot can turn urine and stool a harmless pink or red, an effect called beeturia. It is not blood and not a cause for concern, but it surprises people the first time. Pair your nitrate strategy with a sound in race carbohydrate plan, because nitrate sharpens economy but does nothing to replace the fuel a long effort burns through.
The honest bottom line
Dietary nitrate from beetroot juice is one of the best evidenced legal aids a runner can use. The mechanism is well understood, the dose is established at roughly 6 to 8 mmol taken 2 to 3 hours before the effort, and the typical benefit is a small but real improvement in running economy and time trial performance. Avoid antibacterial mouthwash while you use it, and test it in training before you trust it on race day.
Temper your expectations to your level. If you are a recreational or moderately trained runner, beetroot juice is worth a genuine trial. If you are already very fast, the effect may be small or absent, and your time is better spent on training and recovery than on purple shots.
Frequently asked questions
Does beetroot juice actually improve running performance?
For many runners, yes, but the effect is modest. Dietary nitrate lowers the oxygen cost of submaximal running and can improve time trial performance by a few percent. The benefit is most reliable in recreational and moderately trained runners, and tends to shrink or disappear in highly trained athletes.
How much beetroot juice should I drink before a race?
The evidence points to roughly 6 to 8 mmol of nitrate, which is about 500 ml of standard beetroot juice or one concentrated shot. Take it 2 to 3 hours before the event, when blood nitrite peaks. There is no clear benefit from doses above about 8 mmol.
How long before a race should I take beetroot juice?
Plasma nitrite, the active intermediate, peaks roughly 2 to 3 hours after you drink beetroot juice. Take your dose in that window before the start. For a bigger effect you can also load with a daily dose for 3 to 6 days beforehand, finishing with a dose on race morning.
Why should I avoid mouthwash when taking beetroot juice?
Bacteria on your tongue convert nitrate into nitrite, the step that makes dietary nitrate work. Antibacterial mouthwash kills those bacteria and largely abolishes the rise in plasma nitrite and the drop in blood pressure. Avoid antibacterial mouthwash for the days you are supplementing.
Can I get the same effect from food instead of juice?
Yes. Nitrate is abundant in beetroot, rocket, spinach, chard and other leafy greens. A large spinach or rocket salad can supply a similar nitrate dose to a beetroot shot. Whole foods are a sound everyday source, though juice and shots make it easier to hit a precise dose before a race.
Related reading: Caffeine and running performance: dose, timing and what the evidence shows.
References
- Jones, A.M. (2014) ‘Dietary nitrate supplementation and exercise performance’, Sports Medicine, 44(Suppl 1), pp. 35 to 45. PubMed.
- Bailey, S.J., Winyard, P., Vanhatalo, A. et al. (2009) ‘Dietary nitrate supplementation reduces the O2cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans’, Journal of Applied Physiology, 107(4), pp. 1144 to 1155. PubMed.
- Lansley, K.E., Winyard, P.G., Bailey, S.J. et al. (2011) ‘Acute dietary nitrate supplementation improves cycling time trial performance’, Medicine & Science in Sports & Exercise, 43(6), pp. 1125 to 1131. PubMed.
- Cermak, N.M., Gibala, M.J. and van Loon, L.J.C. (2012) ‘Nitrate supplementation’s improvement of 10-km time-trial performance in trained cyclists’, International Journal of Sport Nutrition and Exercise Metabolism, 22(1), pp. 64 to 71. PubMed.
- Wylie, L.J., Kelly, J., Bailey, S.J. et al. (2013) ‘Beetroot juice and exercise: pharmacodynamic and dose-response relationships’, Journal of Applied Physiology, 115(3), pp. 325 to 336. PubMed.
- Senefeld, J.W., Wiggins, C.C., Regimbal, R.J. et al. (2020) ‘Ergogenic effect of nitrate supplementation: a systematic review and meta-analysis’, Medicine & Science in Sports & Exercise, 52(10), pp. 2250 to 2261. PMC.
- Govoni, M., Jansson, E.Å., Weitzberg, E. and Lundberg, J.O. (2008) ‘The increase in plasma nitrite after a dietary nitrate load is markedly attenuated by an antibacterial mouthwash’, Nitric Oxide, 19(4), pp. 333 to 337. PubMed.
All citations point to peer reviewed primary sources and systematic reviews. Page numbers and volume details are presented per Harvard referencing convention.
Wondering if a few percent would change your race?
PaceBrain reads your training data and gives you an honest race time prediction, so you can see exactly what a small economy gain is worth on the clock. Free, no signup.
Try the predictor