Nitric oxide (NO) is a signaling molecule produced throughout the body that helps regulate blood flow by relaxing the inner muscles of blood vessels, a process known as vasodilation. Maintaining healthy levels of this molecule supports cardiovascular function and overall vascular health. There has been a rise in consumer products, like home salivary or urinary test strips, designed to measure a person’s Nitric Oxide status. These convenient, non-invasive strips offer a quick assessment, prompting questions about their reliability. This article examines the underlying science and accuracy of these popular at-home testing tools.
How the Strips Work
The consumer test strips do not measure the gaseous Nitric Oxide molecule directly because it is highly reactive and breaks down within seconds. Instead, they detect its stable breakdown products, known as metabolites, primarily nitrite and nitrate. The majority of these products specifically focus on measuring nitrite levels in saliva.
The chemical reaction is typically based on the Griess method, which causes a color change when nitrite is present. The resulting color intensity is compared against a provided chart to give a semi-quantitative reading of the nitrite concentration. This measurement relies on the entero-salivary pathway, where dietary nitrate is absorbed, concentrated in the salivary glands, and converted into nitrite by specialized bacteria residing on the tongue.
Addressing the Accuracy Question
Evaluating the accuracy of these strips requires distinguishing between two types of reliability. Analytical accuracy asks whether the strip correctly measures the nitrite concentration in the saliva sample itself. Studies confirm the strips perform well in this regard, showing a strong correlation with sophisticated laboratory methods for measuring salivary nitrite.
Clinical validity asks if the measured salivary nitrite concentration accurately reflects the body’s overall systemic Nitric Oxide status or vascular function. Here, the data shows a significant limitation. Research indicates a lack of correlation between salivary nitrite levels and established markers of systemic NO production, such as plasma nitrite or cGMP concentration.
Plasma nitrite is often considered a better, though still imperfect, indicator of endothelial function and total NO bioavailability throughout the body. Because the strips only measure the nitrite present in the saliva, they are highly accurate chemical indicators of that specific local environment. However, they are poor diagnostic tools for assessing the overall health of the circulatory system or the body’s true capacity for NO production.
Everyday Factors Affecting Readings
The readings from nitric oxide test strips fluctuate widely, often due to factors unrelated to a person’s long-term vascular health. A primary variable is the immediate dietary intake of inorganic nitrates. Consuming nitrate-rich foods, such as beets or leafy greens like spinach and arugula, can significantly spike salivary nitrite levels shortly before testing.
The presence of necessary oral bacteria is another major factor, as these microorganisms convert dietary nitrate into detectable nitrite. Using antiseptic mouthwash temporarily disrupts this oral microbiome, leading to artificially low readings regardless of diet. Similarly, antibiotics reduce the bacterial population, suppressing the conversion process and skewing results.
The timing of the test also introduces variability, with different metabolic states throughout the day affecting results. Even simple factors like hydration levels can impact the concentration of nitrite in the saliva sample.
Practical Use of Test Results
Users should not treat nitric oxide test strips as a diagnostic tool for serious health conditions, and medical decisions regarding cardiovascular health should never be based solely on the results. Instead, the strips are best utilized as a tool for biofeedback and compliance monitoring.
They can effectively confirm whether a lifestyle intervention is succeeding in its immediate goal of increasing the raw material for the NO pathway. For example, a user can test before and after adopting a diet higher in nitrate-rich vegetables to see if their salivary nitrite level has increased. This provides immediate, personalized feedback and serves as a motivator for maintaining positive dietary changes.
The strips function as a way to track the short-term effectiveness of dietary choices or supplements designed to support the nitrate-nitrite-NO pathway. By monitoring the results over time and under standardized conditions, users can gain insights into how their body responds to specific inputs.