Nitric Oxide: The Hidden Driver of Health and Performance

Nitric oxide is a tiny molecule that has a big impact on our health and performance. It’s a key signalling compound that’s found throughout the body and supports vascular, neural, immune, and metabolic functions. This makes it essential for maintaining overall health.

In recent years, it has attracted growing interest within sports science because of its potential to enhance exercise performance and accelerate recovery. Despite its importance, nitric oxide remains largely undervalued and poorly understood. Yet, a relatively basic knowledge of this simple molecule can unlock numerous nitric oxide benefits for both daily health and athletic performance.

In this article, we’ll explore the functions of nitric oxide and how we can optimise its production and availability.

How nitric oxide is produced

There are two primary pathways for the body’s production of nitric oxide. The first is the nitric oxide synthase (NOS) pathway. This involves the generation of nitric oxide from the amino acid arginine. This uses oxygen and several essential cofactors, facilitated by a group of enzymes known as nitric oxide synthases. It occurs in a number of key locations in the body. These include the blood vessels, nerve cells, and immune cells. Smaller amounts of nitric oxide are also produced in other areas such as muscle, liver, pancreas, kidneys, and reproductive tissues.

The second route is the nitrate–nitrite–nitric oxide pathway. In this process, dietary nitrates from foods like beetroot and leafy greens are converted to nitrites by ‘friendly’ bacteria in the mouth and to nitric oxide in the body. It’s the combined effect of these two pathways that ensures adequate nitric oxide availability. Ultimately, they provide numerous nitric oxide benefits for both health and exercise performance.

Nitric oxide and its impact on health

Nitric oxide’s effects are so far-reaching that it’s difficult to overstate its importance for health. Its effects can be seen across several major areas, including:

• In the cardiovascular system, it regulates blood vessel dilation, controls blood pressure, enhances circulation, and reduces arterial stiffness.
• In the nervous system, it functions as a neurotransmitter, aiding memory and neural communication. It enhances immune function by helping to destroy pathogens, modulating inflammation, and promoting wound healing.
• In the respiratory system, nitric oxide helps to regulate airway dilation and oxygen uptake.
• Concerning metabolic health, it enhances cellular energy production, mitochondrial function, and glucose metabolism.
• In the digestive tract, it promotes smooth muscle relaxation and healthy gut motility.
• By promoting vasodilation (e.g., widening of the blood vessels due to the relaxation of the smooth muscle within their walls), nitric oxide enhances blood flow to the sexual organs. When nitric oxide levels are low, this process becomes impaired, resulting in erectile dysfunction.

Because nitric oxide is central to these processes, maintaining optimal levels offers substantial nitric oxide benefits for overall health and wellbeing.

The role of nitric oxide in exercise performance

Nitric oxide improves exercise performance by increasing blood flow and oxygen delivery to working muscles. This is especially valued in bodybuilding because it creates a temporary increase in muscle size during resistance training, known as the ‘pump’ or transient hypertrophy.

People do not regard nitric oxide as a key ergogenic molecule solely for its ability to produce a good ‘pump’. It also supports numerous physiological processes essential for athletic performance. For example, it controls oxygen delivery and utilisation for the production of adenosine triphosphate (ATP). This high-energy molecule is found in the body’s cells and stores and supplies energy when needed, such as during exercise.

Nitric oxide also plays an important role in increasing the number of mitochondria in the cells. These tiny organelles, known as the ‘powerhouses of the cell,’ provide 90% of the energy needed to sustain life. They convert the food we eat into ATP, which cells can then use to fuel their various functions. In addition, nitric oxide modulates contractile function, hormone regulation, and local circulation in skeletal muscle.

Evidence from research supports these performance benefits. A review by Senefeld et al. (1) highlighted the beneficial effects of nitrate supplementation on performance. Their analysis showed that dietary nitrates, most commonly from beetroot juice, can improve performance across several exercise types. These included endurance exercise, high-intensity efforts, and intermittent sports. Researchers observed the benefits under various environmental conditions, such as heat and hypoxia, where oxygen availability decreases.

The results of another study (2) showed that people with higher oral nitrate reduction capacity performed better on several aerobic fitness measures. This capacity reflects how effectively bacteria in the mouth convert dietary nitrate into nitrite. Higher conversion rates were linked with greater oxygen uptake and higher peak power output. In other words, greater nitrite availability supports better aerobic performance.

Eating to optimise nitric oxide production

The key to optimising nitric oxide levels is good nutrition. You don’t need exotic or novel substances. Everyday foods can meaningfully increase nitric oxide by providing nitrates, antioxidants, or amino acids that support its biological pathways.

Key foods and nutrients include:

• Nitrate-rich vegetables: beetroot, beetroot juice, spinach, rocket, kale, Swiss chard
• Amino acid sources: watermelon (L-citrulline), nuts, seeds (L-arginine), meat and fish
• Antioxidants: citrus fruits, pomegranate, dark chocolate, garlic, and plant compounds

Evidence shows that these foods and supplements increase nitric oxide availability, enhancing circulation, cardiovascular function, exercise tolerance, and other nitric oxide benefits. For example, Webb and colleagues (3) found that consuming nitrate-rich beetroot juice produced a marked increase in nitric oxide, leading to reduced blood pressure and improved vasodilation. Studies show that increased availability from nitrate-rich vegetables also improves exercise efficiency and tolerance during high-intensity activity (4).

Supplements such as L-citrulline, L-arginine, folic acid, and plant flavonoids (quercetin, catechins, anthocyanins, procyanidins) further support nitric oxide production. Interestingly, citrulline supplementation increases arginine in the body more effectively than consuming arginine itself, amplifying nitric oxide benefits for both health and performance.

The dangers of mouthwash

Millions of people routinely use antiseptic mouthwash to aid their oral hygiene. However, it may actually be damaging their health and limiting their ability to exercise.

The purpose of antiseptic mouthwash is to kill bacteria. Unfortunately, it not only kills harmful bacteria in the mouth, but also the ‘friendly’ bacteria needed to convert nitrate to nitrite. This in turn decreases nitric oxide bioavailability (5), which, as we have seen, reduces many nitric oxide benefits for both health and performance.

The results of a study by Bescós and colleagues (6) showed that using an antiseptic mouthwash after exercise can significantly impair the body’s nitric oxide pathway. Participants completed a treadmill run and then rinsed with either an antibacterial mouthwash or a placebo. Those who used the mouthwash experienced reduced conversion of nitrate to nitrite in the mouth, which led to lower nitric oxide availability. As a result, it blunted post-exercise vasodilation, inhibited the normal post-exercise reduction in systolic blood pressure, and noticeably reduced muscle oxygenation.

Other studies have also highlighted this relationship between antiseptic mouthwash, nitrite levels, and blood pressure. One showed that use of antiseptic mouthwash for just 7 days caused a significant decrease in nitrite levels, which was accompanied by an increase in blood pressure (7).

It’s important to note that it’s not only antiseptic mouthwash that can inhibit our ability to produce nitric oxide. Due to their sometimes indiscriminate killing of bacteria, antibiotics can also reduce ‘friendly’ oral bacteria, which in turn impairs nitrate-to-nitrite conversion (8).

So, although someone may consume a diet rich in nitrate-containing foods, their ability to increase nitric oxide production may be limited due to a lack of ‘friendly’ bacteria, reducing the potential nitric oxide benefits.

The bottom line

The benefits of maintaining adequate nitric oxide levels for health and performance are well supported by a substantial body of research.

Optimising its availability can be achieved through a diet rich in nitrate-containing foods, supported where appropriate by targeted supplementation. At the same time, it’s important to minimise exposure to factors that may impair its production, such as the disruption of beneficial oral bacteria.

For those looking to develop a deeper understanding of how nutrition influences key physiological processes like nitric oxide production, exploring structured learning such as our nutrition courses can provide valuable, practical insight.

References

1) Senefeld JW, Wiggins CC, Regimbal RJ, Dominelli PB, Baker SE, Joyner MJ. Ergogenic Effect of Nitrate Supplementation: A Systematic Review and Meta-analysis. Med Sci Sports Exerc. 2020 Oct;52(10):2250-2261. doi: 10.1249/MSS.0000000000002363. PMID: 32936597; PMCID: PMC7494956.

2) Thomas B, Smallwood S, Cutler C, Bescos R. The oral nitrate-reducing capacity correlates with peak power output and peak oxygen uptake in healthy humans. Nitric Oxide. 2019 Jun 1;87:43-51. doi: 10.1016/j.niox.2019.03.001. Epub 2019 Mar 7. PMID: 30853629.

3) Webb AJ, Patel N, Loukogeorgakis S, Okorie M, Aboud Z, Misra S, et al. Acute ingestion of beetroot juice reduces blood pressure in healthy men. Hypertension. 2008;51(3):784–790.

4) Porcelli S, Ramaglia M, Bellistri G, Pavei G, Pugliese L, Montorsi M, et al. Aerobic fitness affects the exercise performance responses to nitrate supplementation. Med Sci Sports Exerc. 2016;48(5):1043–1051

5) Joshipura KJ, Muñoz-Torres FJ, Morou-Bermudez E, Patel RP. Over-the-counter mouthwash use and risk of pre-diabetes/diabetes. Nitric Oxide. 2017 Dec 1;71:14-20. doi: 10.1016/j.niox.2017.09.004. Epub 2017 Sep 20. PMID: 28939409; PMCID: PMC6628144.

6) Bescós R, Ashworth A, Cutler C, Brookes Z, Belfield L, White D, et al. Effects of antibacterial mouthwash on the post exercise hypotensive response and nitric oxide bioavailability. Free Radic Biol Med. 2019;143:252–259

7) Kapil V, Haydar SM, Pearl V, Lundberg JO, Weitzberg E, Ahluwalia A. Physiological role for nitrate-reducing oral bacteria in blood pressure control. Free Radic Biol Med. 2013 Feb;55:93-100. doi: 10.1016/j.freeradbiomed.2012.11.013. Epub 2012 Nov 23. PMID: 23183324; PMCID: PMC3605573.

8) Hyde ER, Luk B, Cron S, et al. Characterization of the rat oral microbiome and the effects of antibiotics on nitrate reducing bacteria and nitrate reduction. Microb Ecol. 2014;68(1):21 33.

Author

Paul Orridge

Paul Orridge BSc (Hons)

Paul Orridge is a graduate in the field of sport, exercise and health, and has over 30 years’ experience within the fitness industry. In this time, he has performed a variety of roles including personal training, lecturing and writing. Paul now works as a freelance technical author and subject matter expert within the fitness industry. His work is based on his practical experience gained working with a diverse range of people from very unfit, overweight individuals to highly conditioned athletes, and is underpinned by the latest research.