Nitric oxide (NO) as an important helper in the body

Nitric oxide is more commonly known as a problematic environmental pollutant from vehicle and industrial exhaust. It is an aggressive gas that can damage the airways and impair oxygen transport in the body at high concentrations. But nitric oxide also has another side that is extremely important and useful for us.

High blood pressure damages, among other things, the innermost layer of the blood vessels the so-called endothelium. This layer, however, plays an important role in regulating blood pressure, because it influences vessel tone. That helps determine whether a vessel is more constricted and less elastic, or relaxed and flexible. Part of this process is a job of the endothelium: it is involved in the body's own production of nitric oxide (NO).

Besides its relaxing, so-called vasodilatory effect on blood vessels, NO has other important roles in the body. For example, it inhibits platelet aggregation, so it prevents platelets from sticking together and forming clots. On the surface of the endothelium it reduces the formation of certain molecules that enable white blood cells to attach which is the first stage of atherosclerosis. NO also reduces the formation of free radicals and the oxidation of fats, both of which contribute to atherosclerosis. And it also has an anti-inflammatory effect in the body.

So NO is beneficial for blood vessels in several ways: it relaxes and widens them, counteracts the development of atherosclerosis that narrows the vessel, and has anti-inflammatory effects. Inflammation, in turn, would lead to further narrowing. It also reduces the formation of blood clots that could get stuck in narrow spots and cause a vessel blockage.

Where does the useful NO in the body come from?

The body produces NO in the endothelial cells that line the blood vessels. For this it needs an enzyme called nitric oxide synthase, which combines the nitrogen-containing amino acid arginine with oxygen. The resulting arginine molecule then releases NO. The remainder of the molecule is further processed. The "raw material" arginine is also produced by the body at least when you're young.

But immune cells the macrophages can also produce NO to fight bacteria.

NO is also produced in higher amounts in the nasal sinuses and then taken in through the breath especially when breathing through the nose. This lowers vascular resistance in the lungs and improves oxygen uptake. There is evidence that the increased NO production in the sinuses is a defense mechanism of the body against bacteria and viruses.

Unfortunately, the body's own NO production decreases with age. This is partly due to reduced production of arginine in the body itself. Arginine can, however, be supplied relatively easily through the diet. Sunflower seeds, nuts and legumes are, for example, good sources of arginine. But the endothelium itself also ages and loses some of its function.
A study published in 2025 showed that older people responded better than younger people to drinking nitrate-rich beetroot juice; the blood pressure of these participants fell. This is attributed to changes in the oral microbiome caused by the juice. Those changes were also detected in younger study participants, but they did not lead to a blood pressure reduction in them possibly because their blood pressure was already in the normal range.

NO precursors in the form of inorganic nitrates can also be taken in with food. In the body these are first converted into nitrite, from which the body can then produce NO in further steps. A well-researched and blood-pressurebeneficial source of these precursors is beetroot especially as juice. But other vegetables (especially green leafy vegetables) also contain these important compounds.

The following image shows how this conversion takes place in the body:

Because the converted NO is ultimately available again in the salivary glands, it can be inhaled with every breath. Studies have shown that after drinking 500 ml of beetroot juice, the nitric oxide level in the exhaled breath of COPD patients was more than 200 percent higher than before consuming the drink.

Organic Beetroot Juice R³benherz

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Sources:

This article comes from BloodPressureDB – the leading app since 2011 that helps hundreds of thousands monitor their blood pressure every day. Our content is based on carefully researched, evidence-based data and is continuously updated (as of 08/2025).

Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as in outpatient care, and has led BloodPressureDB's specialist editorial team since 2015. Thanks to her extensive additional qualifications as a paramedic, first responder and in various therapy and emergency areas, she provides solid, practical and reliably reviewed information.

Nitric oxide (NO) as an important helper in the body

Where does the useful NO in the body come from?

Organic Beetroot Juice R³benherz

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