Dietary nitrate
A nitrate supplement still has to be converted, and that step happens in your mouth.
Beetroot juice, nitrate salts and nitric oxide boosters all enter the same pathway. Whether it runs depends on bacteria.
Nitrate supplements — beetroot juice, nitrate salts, products sold as nitric oxide boosters — all supply the same starting molecule that leafy greens and beets do. What happens next is the part worth understanding. Nitrate is absorbed, concentrated into saliva by the salivary glands, and delivered back to the tongue, where bacteria reduce it to nitrite. Human cells do not perform that reduction efficiently, so the step depends on the microbial community rather than on the dose. Studies that suppressed oral bacteria with antibacterial rinses found nitrite fell despite nitrate still being available — the input arrived and the conversion did not.
What these products supply
Beetroot juice and powder, nitrate salts, and products marketed as nitric oxide boosters differ in format and concentration, and they share a starting point: inorganic nitrate, the same molecule abundant in leafy green vegetables and beets.
Nitrate itself is not nitric oxide. It is two conversions away.
The pathway, in brief
Nitrate is absorbed in the small intestine and enters the circulation. A substantial share is then taken up by the salivary glands and concentrated into saliva, at levels well above those in blood.
Concentrating something into saliva rather than clearing it is an active process, which is generally a sign that something is being done deliberately. The full pathway is set out on the nitric oxide page.
The step your own cells do not perform
Reducing nitrate to nitrite is the step human cells do not carry out efficiently. Oral bacteria do.
That is the whole reason this page exists. A pathway the body relies on runs, at one point, through organisms that are not part of the body.
Where the conversion happens
Largely on the tongue's dorsum, in the deeper parts of the coating where oxygen is low — conditions that favor organisms able to use nitrate as an alternative electron acceptor.
Veillonella, Actinomyces, Rothia and Neisseria are among the genera involved. They are ordinary residents of a healthy mouth.
What happened when the bacteria were suppressed
This is where the dependency was tested rather than assumed. Investigators used antibacterial rinses, chlorhexidine among them, to suppress the oral community while dietary nitrate continued.
Salivary and plasma nitrite fell. In studies that also recorded vascular readings, including one in treated hypertensive participants, measurable changes in blood pressure accompanied the drop. The nitrate was still arriving; the conversion was not happening.
Why the same dose does different things
Oral communities differ between people, and so does nitrate-reducing capacity. The same intake therefore does not produce the same conversion in everyone.
Network analyzes of nitrate-sensitive oral communities across dietary interventions describe considerable between-person variation — and the variation is in the community, not in the nitrate.
What can interrupt the step
Antibacterial rinse use is the best-documented interruption. Periodontal disease has been associated with reduced nitrate-reduction capacity. Smoking and reduced saliva flow both change conditions on the tongue, and how often the tongue is cleaned has been associated with differences in the community and in nitrate handling.
None of that is advice. It is the list of things that act on the same step.
Input and capacity are different quantities
A supplement label reports the input: how much nitrate arrives. That number says nothing about the conversion, because the conversion is not performed by the product.
Nitrate availability also acts on the community itself — it has been studied as a potential prebiotic for the oral microbiome, shifting composition rather than only passing through it. Input and capacity move somewhat together, and they are still two quantities.
What is still being studied
Whether between-person differences in oral nitrate-reducing capacity translate into differences in vascular readings over time. Whether raising that capacity changes anything durably. How the community as a system, rather than any single organism, governs the conversion. All of it is open.
Where the research is
Where the relevant findings sit.
Nitrate from food or supplements is concentrated into saliva and delivered back to the mouth — the enterosalivary cycle.
Oral bacteria reduce nitrate to nitrite; human cells do not perform this step efficiently.
Nitric oxide is involved in the regulation of vascular tone.
Suppressing oral bacteria with antibacterial rinses lowers salivary and plasma nitrite even when nitrate intake continues.
Nitrate availability shifts oral community composition, and has been studied as a potential prebiotic for the oral microbiome.
Nitrate-reduction capacity is reduced in periodontitis.
Whether between-person differences in oral nitrate-reducing capacity relate to vascular readings over time.
Whether raising nitrate-reducing capacity changes anything durably.
In context
The rest of the pathway
Absorption, salivary concentration and downstream conversion all sit around the oral step. The mouth is one stage of several.
Antibacterial rinses
The best-documented interruption to this step, and the one most likely to be happening without anyone noticing.
The rest of the community
Periodontal disease has been associated with reduced capacity, so the state of the mouth is part of the picture.
Your physician
Vascular measurements are made with instruments and interpreted by clinicians. None of that is a saliva measurement.
How OraPath measures this
The Oral Balance Test targets the narG gene, which encodes part of the enzyme performing the conversion. Detecting the gene indicates the capacity is present in your community.
Those detections feed the Nitric Oxide System reading, which describes the oral step of the pathway — what your mouth can do with nitrate, whether that nitrate arrives from food or anywhere else.
Measure the step the pathway depends on.
Curious what your oral microbiome looks like? The Oral Balance Test measures targeted organisms and microbial functions from a saliva sample processed in our Norman, Oklahoma laboratory.
Common questions
Do nitrate supplements work without the right oral bacteria?
The conversion from nitrate to nitrite is performed by bacteria, not by the product. Studies suppressing oral bacteria found nitrite fell while nitrate intake continued.
Does mouthwash interfere with beetroot juice?
Experimental studies using antibacterial rinses to suppress oral bacteria reported lower salivary and plasma nitrite, and in some, measurable changes in blood pressure readings.
Is nitrate the same as nitric oxide?
No. Nitrate is two conversions away — first reduced to nitrite by oral bacteria, then converted further downstream.
Why do people respond differently to the same dose?
Oral communities differ between people and so does nitrate-reducing capacity. The variation sits in the community rather than in the nitrate.
Is dietary nitrate from food different from a supplement?
Both supply inorganic nitrate into the same pathway. Vegetables deliver it alongside everything else in the food; a supplement delivers a measured amount of the compound.
Can I measure whether my mouth performs the conversion?
The Oral Balance Test targets the narG gene, which encodes part of the enzyme that performs it. Detecting the gene indicates the capacity is present.
References
- Lundberg JO, Weitzberg E, Gladwin MT. The nitrate–nitrite–nitric oxide pathway in physiology and therapeutics. Nat Rev Drug Discov. 2008;7(2):156–167.
- Hezel MP, Weitzberg E. The oral microbiome and nitric oxide homeostasis. Free Radic Biol Med. 2015;105:48–57.
- Kapil V, Haydar SM, Pearl V, et al. Physiological role for nitrate-reducing oral bacteria in blood pressure control. Free Radic Biol Med. 2013;55:93–100.
- Bondonno CP, Liu AH, Croft KD, et al. Antibacterial mouthwash blunts oral nitrate reduction and increases blood pressure in treated hypertensive men and women. Am J Hypertens. 2015;28(5):572–575.
- Vanhatalo A, Blackwell JR, L'Heureux JE, et al. Nitrate-responsive oral microbiome modulates nitric oxide homeostasis and blood pressure in humans. Free Radic Biol Med. 2018;124:21–30.
- Vanhatalo A, L'Heureux JE, Kelly J, et al. Network analysis of nitrate-sensitive oral microbiome reveals interactions with cognitive function and cardiovascular health across dietary interventions. Redox Biol. 2021;41:101933.
- Rosier BT, Buetas E, Moya-Gonzalvez EM, et al. Nitrate as a potential prebiotic for the oral microbiome. ISME J. 2020;14:2459–2469.
- Rosier BT, Takahashi N, Zaura E, Krom BP, Marsh PD. The importance of nitrate reduction for oral health. J Dent Res. 2022;101(8):887–897.
- Rosier BT, Moya-Gonzalvez EM, Corell-Escuin P, et al. Nitrate reduction capacity of the oral microbiota is impaired in periodontitis. Int J Oral Sci. 2024;16:3.
- Tribble GD, Angelov N, Weltman R, et al. Frequency of tongue cleaning impacts the human tongue microbiome composition and enterosalivary circulation of nitrate. Front Cell Infect Microbiol. 2019;9:39.
Laboratory developed test · for adjunctive clinical use · not FDA cleared.