Nitric Oxide and Infrared Sauna: What the Science Says About Circulation, Supplements, and Testing Your Levels
Discover how nitric oxide supports healthy circulation, and why our infrared sauna sessions may help boost it naturally. Learn what the science says about supplements, and how test strips let you see your results before and after each session.
Tonia Mantakaki Wright BSc, MSc - Co-founder of The Wellness Collective
8/10/20265 min read
If you've spent any time in the wellness world, you've probably heard nitric oxide mentioned alongside circulation, heart health, and sauna therapy. But what actually is it, how does your body make it, and does an infrared sauna session really move the needle? Here's what the research shows — and why we offer nitric oxide test strips alongside our infrared sauna sessions at The Wellness Collective Bristol.
What Is Nitric Oxide?
Nitric oxide (NO) is a small signalling gas produced naturally inside your body, mainly by the cells lining your blood vessels (the endothelium). Its most well-known job is vasodilation: it tells the smooth muscle in your blood vessel walls to relax, which widens the vessel and improves blood flow. This happens through a chain reaction involving an enzyme called endothelial nitric oxide synthase (eNOS), which triggers a cascade that lowers calcium inside the muscle cells and allows them to relax.
Because of this role, nitric oxide is often described as a master regulator of vascular tone — it influences blood pressure, how efficiently oxygen and nutrients reach your tissues, and even platelet activity. Reduced NO availability is one of the earliest markers of poor vascular health, which is why supporting healthy NO production is of real interest for circulation and cardiovascular wellness.
How Your Body Produces Nitric Oxide Naturally
Nitric Oxide and Infrared Sauna Use
There are two main pathways:
The enzymatic pathway — your body converts the amino acid L-arginine into nitric oxide via the eNOS enzyme. This pathway is activated by physical stimuli, particularly the increased blood flow and "shear stress" against vessel walls that happens during exercise.
The nitrate–nitrite–NO pathway — nitrate from foods such as leafy greens and beetroot is converted by bacteria in your mouth into nitrite, which your body can then convert into NO, especially in tissues where oxygen is limited.
Exercise is one of the most reliable natural triggers of NO production, because increased circulation itself stimulates the endothelium to produce more. Heat exposure appears to work through a similar mechanism, which is where infrared sauna use comes in.
Supporting Nitric Oxide Through Diet and Supplements
Infrared saunas heat the body directly rather than heating the surrounding air, and this raises core temperature and heart rate in a way that's often compared to moderate exercise. Several lines of research point to a genuine link between this heat exposure and nitric oxide activity:
Animal studies have shown that repeated far-infrared heat exposure meaningfully increases eNOS expression in blood vessel walls, alongside higher circulating NO metabolites.
Human studies using far-infrared sauna sessions have reported improved flow-mediated dilation (a standard ultrasound measure of how well an artery widens in response to increased blood flow), which is considered a marker of healthy endothelial function.
Population research on regular sauna users (predominantly traditional, Finnish-style sauna) has linked frequent sessions with meaningfully lower rates of cardiovascular events over decades of follow-up, with improved vascular function proposed as one contributing mechanism.
The overall picture is consistent: heat stress appears to prompt the endothelium to produce more nitric oxide, supporting the case for infrared sauna as a circulation-supportive addition to a wellness routine.
A quick note: because sauna sessions place a real, if temporary, demand on the cardiovascular system, anyone with an existing heart condition, uncontrolled blood pressure, or who is on cardiovascular medication should check with their GP before starting regular sauna use.
If you want to support your body's own NO production between sauna sessions, nutrition research points to a few genuinely evidence-backed options:
Dietary nitrate (from beetroot, spinach, rocket, and other leafy greens) has consistently been shown to raise NO availability and is the best-supported route of the three.
L-citrulline supplementation has reasonable evidence behind it, as it's converted to L-arginine more efficiently than taking arginine directly.
L-arginine on its own has more mixed evidence. Several studies have found that a single dose doesn't meaningfully raise NO production in healthy adults, likely because arginine is broken down before it reaches the enzyme that needs it.
In short: food-based nitrate and citrulline currently have stronger scientific backing than arginine supplements alon
Measuring Nitric Oxide: Why We Use Test Strips Before and After Your Sauna Session
At The Wellness Collective Bristol, we offer nitric oxide test strips so you can get a qualitative, visual snapshot of your saliva nitrite levels before and after your infrared sauna session. Here's what's genuinely useful about this — and what to keep in mind:
What they're good for: These strips measure salivary nitrite, which is used as a practical surrogate marker for NO activity. Research validating these strips has found they're reliable at picking up changes in your levels over time — for example, showing a shift after a sauna session, a change in diet, or the addition of a nitrate-rich food. That makes them a genuinely useful, non-invasive way to see your own body respond in real time and stay motivated to keep up habits that support circulation.
What they can't do: The same research is clear that these strips aren't precise enough to give an exact absolute concentration of nitric oxide in your body, and salivary nitrite doesn't directly equal circulating (systemic) NO. Results can also be affected by things like mouthwash use, smoking, and individual variation in oral bacteria. So we treat the strips as a trend-tracking tool and conversation starter (a way to visualise the direction your body is moving in) rather than a clinical diagnostic measurement.
Used this way, a before-and-after strip test can be a simple, motivating way to see your infrared sauna session in action.
The Takeaway
Nitric oxide is central to healthy circulation, and there's a genuine, growing body of research connecting infrared sauna use to improved NO activity and vascular function. Pairing your sauna sessions with a nitrate-rich diet — and, if you're curious, a before-and-after test strip — is a simple, evidence-informed way to support your circulation and see your own progress.
IF you are curious to try it for yourself, book an infrared sauna session with us and ask about adding a nitric oxide test strip to see your results first-hand.
References
Ikeda, Y., et al. (2001). Repeated thermal therapy upregulates endothelial nitric oxide synthase and augments angiogenesis in a mouse model of hindlimb ischemia. Journal of the American College of Cardiology.
Akasaki, Y., et al. Repeated thermal therapy upregulates endothelial nitric oxide synthase and augments angiogenesis, cardiovascular/endothelial research summary. Hypertension Research.
Laukkanen, T., et al. (2015). Sauna bathing and risk of fatal and non-fatal cardiovascular events. JAMA Internal Medicine.
Cardiovascular Physiology overview of nitric oxide-mediated vasodilation via the cGMP pathway, CVPhysiology.com.
Babateen, A. M., Shannon, O. M., Mathers, J. C., & Siervo, M. (2019). Validity and reliability of test strips for the measurement of salivary nitrite concentration with and without the use of mouthwash in healthy adults. Nitric Oxide, 91, 15–22.
Modi, A., et al. (2017). Validation of two point-of-care tests against standard lab measures of NO in saliva and in serum. Nitric Oxide, 64, 16–21.
Jones, A. M., et al. (2018). Dietary nitrate and physical performance. Annual Review of Nutrition.
Bescós, R., et al. Acute L-arginine supplementation does not increase nitric oxide production in healthy subjects. Nitric Oxide research summary.
GoodRx Health (2026). Nitric Oxide Supplements: What They Are, Benefits, Side Effects — overview of citrulline and arginine supplementation evidence.
This article is for general educational purposes and does not replace individual medical advice. Please speak with your GP before starting infrared sauna sessions if you have a cardiovascular condition or take related medication.