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6 min readrunning / endurance

4.2 mmol did nothing, 8.4 worked: how to dose beetroot juice

A bottle of beetroot concentrate sat in my fridge for two seasons while I drank one shot on race morning, an hour before the gun. Two of those three decisions were wrong, and the dose-response paper that says so has been public since 2013. Nitrate is one of the cheapest things in endurance nutrition and one of the easiest to waste.

The mechanism pays out as a cheaper stride.

Swallowed nitrate reaches the bloodstream, returns to the mouth in saliva, and bacteria on the back of the tongue reduce it to nitrite. Nitrite becomes nitric oxide in the circulation, and the measurable consequence is less oxygen burned for the same watts.

Stephen Bailey's group at Exeter ran the trial that opened the field. Eight men drank 500 mL of beetroot juice a day for six days. Oxygen uptake during moderate cycling fell, the slow component during severe cycling was blunted, and time to exhaustion rose 15.8% against a placebo that held at 583 ± 145 seconds 1.

Katherine Lansley took the same juice to a performance test. Nine club-level male cyclists drank 0.5 L containing about 6.2 mmol of nitrate, or a nitrate-depleted version, 2.5 hours before racing. The 4 km trial came in 2.8% faster and the 16.1 km trial 2.7% faster, carried by 5% and 6% more mean power 2.

Pooled, the effect is smaller than either trial suggests. Nicholas McMahon, Michael Leveritt and Toby Pavey meta-analysed the endurance literature and found a small-to-moderate effect on time to exhaustion, 0.33 (95% CI 0.15 to 0.50), with time-trial performance less likely to respond 4. Open-ended tests answer the question "how long can you hold this". Time trials ask you to distribute effort over a fixed distance, and nitrate helps less there.

The dose curve has a floor and a ceiling.

Lee Wylie ran the experiment that should set your shopping list. Ten men drank 70, 140 or 280 mL of concentrate, carrying 4.2, 8.4 or 16.8 mmol of nitrate, then cycled 2.5 hours later. Plasma nitrite peaked 2 to 3 hours after drinking. The 8.4 mmol dose raised exercise tolerance. The 4.2 mmol dose did not. Doubling to 16.8 mmol bought nothing further 3.

That puts a hard number on the label: 8.4 mmol of nitrate is about 520 mg. Most concentrate shots print milligrams, some print mmol, and the two differ by a factor of 62. One small shot is often half the effective dose, which is the mistake I was making.

Vegetables reach the same plasma concentration. Kristin Jonvik's team at Maastricht gave 18 adults four drinks each carrying 800 mg (about 12.9 mmol) of nitrate: sodium nitrate, beetroot concentrate, a rocket beverage and a spinach beverage. Peak plasma nitrate landed within 14 µmol/L across all four, from 583 ± 29 to 597 ± 23 µmol/L 8. Rocket and spinach work if you hit the milligrams.

One habit cancels the whole protocol. Mirco Govoni gave seven volunteers an oral nitrate load with and without a chlorhexidine mouthwash. The mouthwash left nitrate accumulation in saliva untouched, abolished its conversion to nitrite there, and markedly attenuated the rise in plasma nitrite 7. The bacteria doing the first step live in your mouth, and antibacterial rinse kills them.

It fades as you get faster.

Henrique Campos and colleagues pooled 53 placebo-controlled studies. Non-athletes gained, effect size 0.25 (95% CI 0.11 to 0.38), rising to 0.47 (95% CI 0.23 to 0.71) for long open-ended tests. Athletes gained 0.04 (95% CI -0.05 to 0.15), an interval that sits on zero 5.

Peter Christensen showed why in one clean trial. Ten elite cyclists at 72 ± 4 mL O2/kg/min took 0.5 L of beetroot juice daily for six days. Plasma NOx climbed from around 40 µM to 147-159 µM, so the nitrate arrived. VO2 kinetics, exercise economy, a 400 kcal time trial and six 20-second sprints were all unchanged 6.

Well-trained endurance athletes already run high muscle blood flow and efficient oxygen use, and there is less slack for nitric oxide to take up. I sit nowhere near 72 mL/kg/min, and neither do most people reading this, which is the honest reason to keep a bottle in the fridge. If your VO2max is above 65, treat the evidence as pointing away from you.

The protocol.

  1. Buy on milligrams. Target 8.4 mmol, about 520 mg of nitrate, in one serving. Below that dose, Wylie's 4.2 mmol arm moved nothing 3.
  2. Drink it 2.5 hours before the start. Plasma nitrite peaks at 2 to 3 hours 3, and both performance trials dosed at 2.5 23.
  3. Stop at one serving. The 16.8 mmol arm performed no better than 8.4 3, so a second shot costs money and stomach room.
  4. For a goal race, load for 6 days and keep the race-morning dose. Bailey's O2 cost reduction and Christensen's plasma numbers both came from 500 mL daily across six days 16.
  5. Ban antibacterial mouthwash from the day before through the finish, and swallow your saliva rather than spitting it out. Chlorhexidine blocked the salivary conversion step outright 7.
  6. Swap in rocket or spinach if the concentrate wrecks your stomach, matching the same 500+ mg. Four nitrate sources produced peak plasma nitrate within 14 µmol/L of each other 8.
  7. Rehearse it twice at goal pace before you race on it. Beeturia and a loose stomach on race morning are worth discovering in a Tuesday session.
  8. Test it on yourself before you believe any of this. Run the same 20-minute effort on the same course six times, three with the dose and three without, and compare the gap between conditions against the spread inside each set of three. The pooled effect for trained people sits at 0.04 5; if your own variation swamps the difference, spend the money on carbohydrate instead.

Sources.

  1. Bailey, S. J., Winyard, P., Vanhatalo, A., Blackwell, J. R., DiMenna, F. J., Wilkerson, D. P., Tarr, J., Benjamin, N., & Jones, A. M. (2009). Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans. Journal of Applied Physiology, 107(4), 1144-1155. doi.org/10.1152/japplphysiol.00722.2009
  2. Lansley, K. E., Winyard, P. G., Bailey, S. J., Vanhatalo, A., Wilkerson, D. P., Blackwell, J. R., Gilchrist, M., Benjamin, N., & Jones, A. M. (2011). Acute dietary nitrate supplementation improves cycling time trial performance. Medicine & Science in Sports & Exercise, 43(6), 1125-1131. doi.org/10.1249/MSS.0b013e31821597b4
  3. Wylie, L. J., Kelly, J., Bailey, S. J., Blackwell, J. R., Skiba, P. F., Winyard, P. G., Jeukendrup, A. E., Vanhatalo, A., & Jones, A. M. (2013). Beetroot juice and exercise: pharmacodynamic and dose-response relationships. Journal of Applied Physiology, 115(3), 325-336. doi.org/10.1152/japplphysiol.00372.2013
  4. McMahon, N. F., Leveritt, M. D., & Pavey, T. G. (2017). The effect of dietary nitrate supplementation on endurance exercise performance in healthy adults: a systematic review and meta-analysis. Sports Medicine, 47(4), 735-756. doi.org/10.1007/s40279-016-0617-7
  5. Campos, H. O., Drummond, L. R., Rodrigues, Q. T., Machado, F. S. M., Pires, W., Wanner, S. P., & Coimbra, C. C. (2018). Nitrate supplementation improves physical performance specifically in non-athletes during prolonged open-ended tests: a systematic review and meta-analysis. British Journal of Nutrition, 119(6), 636-657. doi.org/10.1017/S0007114518000132
  6. Christensen, P. M., Nyberg, M., & Bangsbo, J. (2013). Influence of nitrate supplementation on VO2 kinetics and endurance of elite cyclists. Scandinavian Journal of Medicine & Science in Sports, 23(1), e21-e31. doi.org/10.1111/sms.12005
  7. Govoni, M., Jansson, E. A., Weitzberg, E., & 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), 333-337. doi.org/10.1016/j.niox.2008.08.003
  8. Jonvik, K. L., Nyakayiru, J., Pinckaers, P. J. M., Senden, J. M. G., van Loon, L. J. C., & Verdijk, L. B. (2016). Nitrate-rich vegetables increase plasma nitrate and nitrite concentrations and lower blood pressure in healthy adults. The Journal of Nutrition, 146(5), 986-993. doi.org/10.3945/jn.116.229807

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