Nitrate and exercise performance

Nitrate and exercise performance is one of the most studied topics in sports nutrition. Nitrate is one of the handful of ergogenic substances with solid evidence behind them. Keep reading to find out what is nitrate, its roles in the body and how it can benefit your athletic endeavours.

What is nitrate

Nitrate (NO₃⁻) is an anion, i.e. a molecule with more electrons than protons.

Nitrate is naturally found in plant foods such as leafy greens and root vegetables, including lettuce, spinach, rocket, celery and beetroot (1, 2).

The role of nitrate in the body

Some of the nitrate taken in the diet is converted to nitric oxide (NO) (1, 2). This process starts in the mouth, where a portion of the ingested nitrate (NO₃⁻) is converted to nitrite (NO₂⁻) by oral bacteria. Some of the NO₂⁻ is converted to NO in the stomach thanks to the low (acid) pH, some goes to the blood and is converted to NO by enzymes and proteins (2).

Therefore, we can say the role of nitrate in the body is to increase the production of nitric oxide, which in turn can:

• regulate blood flow (2)
• regulate muscle contraction/function (1, 2)
• enhance type II muscle fibres (1)
• regulate glucose balance (2)
• regulate calcium balance (2)
• enhance mitochondrial respiration (1, 2) and generation (2)
• increase blood flow to muscles (1)

Nitrate and exercise performance

Nitrate is one of the handful of performance-enhancing supplements that have a strong level of evidence (grade A) supporting their benefits (3).

Nitrate can reduce blood pressure, the oxygen cost of exercise (VO₂) (2) and time to exhaustion (1, 2).

The evidence pointing at nitrate as an exercise performance enhancer is most consistent for continuous high intensity exercise lasting 5-30 minutes (2) and intermittent high-intensity team-sport exercise lasting 12-40 minutes (1). The effects of supplementation seem to take 2-6 days (some say up to 15) to show (1, 2). This might be because nitrate needs time to allow for changes in the mitochondria and proteins that act on muscular contraction to take effect (2).

Acute supplementation (i.e. single dose taken on the day of training or competition) has inconsistent results, which could respond to several factors related to the athlete, their diet, as well as the exercise type, intensity and duration (2). For example, trained athletes can benefit less from nitrate supplementation (1, 2). In addition, nitrate seems to act more on type II muscle fibres. Having said that, the studies that do show a benefit of acute nitrate supplementation indicate that the effects are seen after 2-3 hours of ingestion (1).

Cons

If you have been wondering “isn’t nitrate the reason we should avoid processed meats?” you are partially right. Nitrite and nitrate can lead to the formation of nitrosamines in foods, which can cause cancer. However, it appears that this potential issue is minimised by the antioxidants contained in the nitrate-containing vegetables (2). Therefore, the safest bet is to consume nitrate from vegetables or vegetable-derived dietary supplements.

The only rare side effect to nitrate consumption seems to be gastrointestinal upset in some individuals (1). In addition, consumption of nitrate from beetroot leads to beeturia (yes, that is a word) or pink-coloured urine.

Finally, trained athletes may not benefit as much as untrained ones (1).

Summary and recommendations

On top of dietary nitrate intake, nitrate supplementation seems to be consistently effective under the following circumstances:

• taken for 2-6 days before competition
• undertaking high-intensity exercise that lasts 5-30 minutes
• untrained individuals
• athletes who have a higher proportion of type II (“fast twitch”) muscle fibres

If you are considering experimenting with nitrate supplements, choose those derived from vegetables, such as beetroot extract.

References

1. Maughan RJ, Burke LM, Dvorak J, Larson-Meyer DE, Peeling P, Phillips SM, et al. IOC consensus statement: dietary supplements and the high-performance athlete. British Journal of Sports Medicine. 2018;52(7):439-55.
2. Jones AM. Dietary nitrate supplementation and exercise performance. Sports medicine (Auckland, NZ). 2014;44 Suppl 1(Suppl 1):S35-45.
3. Australian Institute of Sport. The AIS Sports Supplement Framework 2019. 2019.

[Photo by K15 Photos on Unsplash]

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