All About Nitrate Supplements for Athletes

Supplements and ergogenic aids have been used throughout the years to promote health, improve exercise performance, and push human ability. Even though some aids, including caffeine and creatine¹, have shown incredible promise in improving exercise performance, the vast majority of supplements have not been tested in a reliable setting, nor do they show consistent scientific evidence backing their claim.

In the past year, there have been dozens of scientific publications on the intake of oral nitrates to improve exercise performance and human health. From a physiological perspective it would make sense that increasing nitrate bioavailability might improve the ability of our muscles to produce work. However, even when something proves promising in the laboratory it can have failed effects in practice.

How Nitric Oxide Works

Nitric oxide (NO) is a powerful messenger molecule in your body. NO is formed from L-arginine in the endothelial cells that line your vasculature. Due to the relatively small size of NO, it is able to diffuse freely across membranes where it can act as a powerful vasodilator to increase blood flow to muscle. NO also helps modulate calcium homeostasis within skeletal muscle to improve contractility². Working muscle requires more blood and more calcium, so increases in NO might naturally improve muscle function during exercise. Sounds pretty good so far right?

The issue with increasing NO surrounds its bioavailability. NO is produced and degraded very fast, in a matter of seconds, so we simply cannot ingest NO to increase levels of it (it’s also a gas). Instead, we must increase the amount of precursor molecules to bolster NO synthesis within the body. Studies increasing L-arginine ingestion do show promise in improving vascular health³, however there remains practical considerations surrounding L-arginine. You need several grams per day to elicit any benefit, and L-arginine has a bitter taste.

Using Beetroot Juice

In comes beetroot juice (BRJ). As you might have guessed, BRJ is liquid naturally extracted from beetroot. Indeed, the recent interest in BRJ has been driven by the discovery of sources of dietary nitrate that could have implications on cardiovascular health. In addition to nitrates, BRJ is rich in other bioactive compounds that may provide additional health benefits

In clinical studies BRJ has been shown to reduce hypertension, and to act as an anti-inflammatory⁴. When ingested, dietary nitrates are reduced to NO in vivo and increase NO concentration. Dietary nitrate found in BRJ also has an extremely high bioavailability with near 100 percent absorption⁵. Unlike L-arginine, BRJ is actually a palatable food, and you don’t need to drink gallons of it to see any effect. In most of the research, the examined dose of BRJ was in the 100-200 mL range, or about 4 to 6 ounces.

Effect on Exercise

So what about it’s effect on exercise? There have been over a dozen publications on the use of BRJ as a performance-enhancer in the last year alone. Research on the topic is exploding, with many of the conclusions unclear or conflicting. However, one thing remains clear: the ability to increase NO during exercise would have positive effects by increasing both:

1. Blood flow to working muscles through increased vasodilation.
2. Skeletal muscle contractility through increased calcium release.

A study published last December showed that BRJ supplementation improved maximal muscle power by 4 percent in untrained individuals doing extremely short “burst” exercises on a bike. The authors claimed that BRJ may benefit power-sports athletes who perform very brief, explosive actions⁶. Another study done by a different lab showed similar results. Ten team-sport athletes were subjected to high-intensity cycling tests over multiple days with and without BRJ ingestion. The group taking BRJ sustained significantly higher power during intermittent, high-intensity exercise⁷. Finally, in a study of 16 participants BRJ supplementation improved sprint performance and reaction time, and more importantly prevented cognitive decline during prolonged intermittent exercise⁸.

Help at High Altitude

Another interesting effect of BRJ supplementation appears in a high altitude environment. At higher altitudes the air is thinner, and it becomes harder for your body to get oxygen to your muscles. The human body will naturally acclimate to this by improving red blood cell formation so that your blood can carry more oxygen. Aside from exercise, BRJ improved vascular function at altitude in healthy individuals⁹ and the authors promoted acute dietary nitrate supplementation as a good strategy to ensure proper endothelial function in those entering high altitudes.

In another double-blind crossover study, 12 subjects completed cycle tests in either low or normal oxygen environments, with or without BRJ. The authors showed that in hypoxic conditions BRJ enhanced oxygen kinetics, and improved exercise tolerance. In line with the previous study, these authors promoted BRJ as a useful supplement to take at altitude¹⁰. BRJ supplementation might also reduce lactate accumulation in the blood while at altitude¹¹, which would help explain increases in exercise tolerance. Even when not taken at altitude, BRJ has been shown to increase exercise tolerance at high-intensity, and to increase red blood cell content in working muscle¹².

Not Everyone Agrees

So is science in complete agreement that BRJ is the next, best workout supplement? Not exactly. In elite endurance athletes BRJ supplementation did not consistently enhance running performance¹³. An additional study in well-trained cyclists showed no improvement from BRJ on time trial performance in normal or hypoxic environments¹⁴. This research infers that elite athletes gain no advantage with BRJ. However, the other studies mentioned hint that those with average fitness taking BRJ appear to increase power output and improve exercise tolerance slightly, especially while at altitude.

Like everything we feed our bodies, more research needs to be done on BRJ to determine the exact mechanisms by which it might improve exercise, to what extent, and in what specific populations. Aside from its effects on human performance, we know that BRJ contains health-promoting phytochemicals¹⁴ just like every other vegetable. However, the exact effect on exercise and the underlying physiological mechanisms remain unclear.

References

1. Tarnopolsky, M.A. (2011, February 22). Caffeine and creatine use in sport. Retrieved from https://pubmed.ncbi.nlm.nih.gov/21346331/
2. Stamler, J.S. & Meissner, G. (2001, January). Physiology of nitric oxide in skeletal muscle. Retrieved from https://pubmed.ncbi.nlm.nih.gov/11152758/
3. Siani, A. et al. (2000, May). Blood pressure and metabolic changes during dietary L-arginine supplementation in humans. Retrieved from https://pubmed.ncbi.nlm.nih.gov/10826408/
4. Vanhatalo, A. et al. (2010, August 11). Acute and chronic effects of dietary nitrate supplementation on blood pressure and the physiological responses to moderate-intensity and incremental exercise. Retrieved from https://pubmed.ncbi.nlm.nih.gov/20702806/
5. Clifford, T. et al. (2015, April 14). The potential benefits of red beetroot supplementation in health and disease. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4425174/
6. Rimer, E.G. et al. (2016, August 24). Acute Dietary Nitrate Supplementation Increases Maximal Cycling Power in Athletes. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4889556/
7. Wylie, L.J. et al. (2015, November 27). Influence of beetroot juice supplementation on intermittent exercise performance. Retrieved from https://pubmed.ncbi.nlm.nih.gov/26614506/
8. Thompson, C. et al. (2015, April 7). Dietary nitrate improves sprint performance and cognitive function during prolonged intermittent exercise. Retrieved from https://link.springer.com/article/10.1007/s00421-015-3166-0
9. Bakker, E. et al. (2015, August 29). Acute dietary nitrate supplementation improves arterial endothelial function at high altitude: A double-blinded randomized controlled crossover study. Retrieved from https://pubmed.ncbi.nlm.nih.gov/26325324/
10. Kelly, J. et al. (2014, July 9). Dietary nitrate supplementation: effects on plasma nitrite and pulmonary O2 uptake dynamics during exercise in hypoxia and normoxia. Retrieved from https://pubmed.ncbi.nlm.nih.gov/25009219/
11. Carriker, C.R. et al. (2015, December 2). Effect of Acute Dietary Nitrate Consumption on Oxygen Consumption During Submaximal Exercise in Hypobaric Hypoxia. Retrieved from https://pubmed.ncbi.nlm.nih.gov/26630309/
12. Aucouturier, J. et al. (2015, May 29). Effect of dietary nitrate supplementation on tolerance to supramaximal intensity intermittent exercise. Retrieved from https://pubmed.ncbi.nlm.nih.gov/26028570/
13. Arnold, J.T. et al. (2015, February 4). Beetroot juice does not enhance altitude running performance in well-trained athletes. Retrieved from https://pubmed.ncbi.nlm.nih.gov/25942474/
14. Bourdillon, N. et al. (2015, October 14). Effect of oral nitrate supplementation on pulmonary hemodynamics during exercise and time trial performance in normoxia and hypoxia: a randomized controlled trial. Retrieved from https://www.frontiersin.org/articles/10.3389/fphys.2015.00288/full