Reference
What the narG gene is, and why OraPath targets it
narG is a bacterial gene that encodes nitrate reductase — the enzyme oral bacteria use to convert dietary nitrate into nitrite. OraPath detects and quantifies narG in saliva by qPCR, so the Nitric Oxide System score reflects measured functional capacity rather than an inference drawn from which species happen to be present. The result is semi-quantitative and is intended for adjunctive clinical use alongside a dentist's examination.
What narG does
Nitrate reductase is the enzyme that removes an oxygen atom from nitrate, turning it into nitrite. Bacteria that carry a functional copy of the narG gene can perform that step; bacteria without it cannot, whatever else they contribute to the mouth.
In the entero-salivary pathway, dietary nitrate from leafy vegetables is absorbed, concentrated in the salivary glands, and returned to the mouth in saliva. Oral bacteria carrying nitrate reductase reduce that nitrate to nitrite, which is swallowed and may be further reduced downstream. This pathway is described in the published literature cited below; OraPath measures the oral step of it and does not measure any later step.
Why a gene, and not a species list
This is the distinction the Nitric Oxide System score rests on.
Most oral panels report which organisms were detected. Reporting a nitrate-reducing genus tells you an organism associated with the function is present. It does not establish that the function is available, because carriage of the gene varies between strains of the same genus, and a species present at low level contributes little regardless of what it carries.
Targeting narG asks a narrower and more answerable question: is the machinery that performs the conversion actually there, and how much of it. That is a measurement of capacity rather than an inference from taxonomy.
The distinction is methodological, not clinical. A narG measurement describes the microbial capability found in one saliva sample at one point in time. It does not describe how much nitric oxide a person produces, and it is not a measurement of anything in the bloodstream.
What each approach can and cannot establish
Both are qPCR measurements of a saliva sample. Neither measures nitric oxide itself.
| Approach | What it reports | What it cannot establish |
|---|---|---|
| Species detection | Which organisms were found, and at what level | Whether the strains present carry the functional gene |
| Functional gene targeting (narG) | Whether the nitrate-reductase gene is present, and at what detection level | Which species carry it, or what the host does downstream |
How OraPath measures it
The Nitric Oxide System score is derived from qPCR detection of narG in a saliva sample, reported on the same Detection Level scale as every other target on the panel.
Detection Level is defined as DL = 40 − Ct. Each additional Detection Level represents roughly twice the quantity of target DNA, and DL 0 means the target was not detected. The scale is semi-quantitative: it supports comparison between samples and over time, and it is not a concentration.
The Nitric Oxide System score is built from four narG detections, each attributed to a genus that carries the gene — Rothia, Neisseria, Veillonella and Actinomyces. The report labels them that way, “Rothia narG” and so on, because what the assay detects in each case is the gene rather than the organism. Those four detections are the measurement, not a species list sitting beside it, and the result is intended to be read by a clinician alongside an examination.
Why the score is rule-based, not machine-learned
The Nitric Oxide System score is produced by documented, version-controlled, rule-based logic. Inputs are measured Detection Levels; the weighting applied to them is written down and can be reproduced from the same inputs.
It is not artificial intelligence and not machine learning. No model is trained on patient data, and no score changes because of what other patients' samples contained.
What this score does not tell you
A narG detection level describes one microbial capability in one saliva sample. It is not a diagnosis of any condition, it does not measure nitric oxide in a person, and it does not establish a cause for anything a patient is experiencing.
The Oral Balance Test is a laboratory developed test performed by IMMYLabs under CLIA. It has not been cleared or approved by the FDA, and results are intended to support a clinician's assessment rather than to replace an examination. Anything a result raises is a reason to discuss it with your dentist.