Faster, Higher, Stronger! In honour of the 2012 London Olympics this week’s post is on one of the latest sport supplement’s – beets! Well, a more concentrated form of the familiar vegetable, beetroot juice. The athletes are all over this supplement as it has few side-effects and it is not on the banned substance list. Can beetroot juice improve performance and put you on top of the podium?
In order to understand how beetroot juice could enhance performance some background information is needed. Initially it was observed that a pharmaceutical, sodium nitrate, reduced the oxygen needed to perform exercise. Essentially the sodium nitrate improved the ability of the muscles to extract energy using the aerobic system (1). However, sodium nitrate is a pharmaceutical product so from an athlete’s perspective it would be far better to obtain it, or an analogue, from dietary sources.
Sodium nitrate is not found in foods, but the nitrate anion is. This molecule is biologically inert; however, the bacteria in the mouth can reduce the nitrate anion to a more bioactive nitrite anion, which can be rapidly absorbed in the gut. The end of the biochemical line comes when sodium nitrite is converted to nitric oxide (NO). Nitric oxide is important because it is a vasodilator (expands your blood vessels), which to an athlete, means it may help deliver nutrients and oxygen to the muscles more effectively. Secondly, it has been hypothesized that the nitric oxide could help improve the efficiency of the production of ATP, commonly called the energy currency of the body (2).
Dietary nitrates are found in our everyday foods, with 60-80% of intakes coming from vegetables in those eating a typical Western diet (3). Adding beets to your salad won’t do the trick though! To increase blood levels of plasma nitrate enough to potentially to impact performance, it is likely that a concentrated form of beetroot juice needs to be consumed. Disclaimer: Athletes, you still need to eat your veggies for optimal performance!
The problem with ergogenic aids in sport is that there are very few legal supplements that actually improve performance. Can beetroot juice help you win gold? Bailey et al. gave 8 males 500 ml/d of beetroot juice for 6 days or a placebo in a cross-over design and found that the beetroot juice increased plasma nitrite concentrations and that the length of time they could cycle before exhaustion was increased (2). Vanhatalo et al. followed up with a second study to assess the effects of different lengths of beetroot juice supplementation. They used 500 ml of beetroot juice for either five days or 15 days. Again plasma levels of nitrite increased over both five and 15 days and blood pressure was reduced. They also found the participants needed less oxygen to maintain a steady amount of submaximal exercise (4). Not just for elite athletes? It appears that beetroot juice could also help those with peripheral arterial disease perform exercise (5). We do note, however, that the majority, if not all of the studies, are of very short duration and have a small number of participants; therefore, the results should be interpreted with caution.
An important question here is whether the effects are indeed due to the nitrate or something else in the beetroot juice. To this end, a nitrate-depleted form of beetroot juice was given to athletes and compared to the beetroot juice containing nitrate. The researchers found that the nitrate-depleted beetroot juice did not increase plasma nitrite levels, lower blood pressure or lower the oxygen cost of walking, running or high intensity running.
No Baloney’s advice? Beetroot juice does seem to have the potential to improve performance, likely for endurance athletes, as shown by these and other studies (7,8) and the benefits appear to be due to the nitrate. When we consider safety, the only side-effect reported appears to be beeturia… when your pee turns red! We should caution, however, that natural nitrates from vegetables and vegetable extracts are different than the nitrites found in processed foods and red meats that have been broiled or BBQed. These have been associated with an increased risk of certain types of cancer.
1. Larsen FJ et al. Effects of dietary nitrate on oxygen cost during exercise. Acta Physiol 2007; 191: 59-66.
2. Bailey et al. Dietary nitrate supplementation reduces the O2 cost of low-intesity exercise and enhances tolerance to high-intensity exercise in humans. J Appl Physiol 2009; 107: 1144-1155.
3. Ysart G et al. Dietary exposures to nitrate in the UK. Food Addit Contam 2009; 16: 521-532.
4. Vanhatalo A et al. Acute and chronic effects of dietary nitrate supplementation on blood pressure and the physiological responses to moderate-intensity and incremental exercise. Am J Physiol Regul Integr Comp Physiol 2010; 299:R1121-31.
5. Kenjale AA et al. Dietary nitrate supplementation enhances exercise performance in peripheral arterial disease. J Appl Physiol 2011; 110:1582-91.
6. Lansley KE et al. Dietary nitrate supplementation reduces the O2 cost of waking and running: a placebo-controlled study. J Appl Physiol 2011; 110:591-600.
7. Lansley KE et al. Acute dietary nitrate supplementation improves cycling time trial performance. Med Sci Sports Exerc 2011; 4: 1125-31.
8. Cermak NM. Nitrate supplemenation’s improvement of 10-km time-trial performance in trained cyclists. Int J Sport Nutr Exerc Metab 2012; 22: 64-71.
*Thanks to the Beastie Boys for inspiring the title of the post!