*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider before starting any supplement.
TL;DR
Nitric oxide (NO) is a molecule your body produces to relax blood vessels, support circulation, and deliver oxygen to tissues. After age 40, production drops significantly. Common signs of low NO include persistent fatigue, cold hands and feet, slow workout recovery, brain fog, and elevated blood pressure readings. Diet, exercise, and targeted supplementation can help support healthy NO levels.
What is nitric oxide and why should you care about it?
Nitric oxide is a short-lived signaling molecule produced naturally in your body. Its primary job is vasodilation — relaxing and widening blood vessels so blood flows more freely. That single function affects almost everything you feel day-to-day: your energy, your mental clarity, your exercise performance, and your cardiovascular health.
For a focused look at this topic, see our beetroot gummies for natural energy.If you want a deeper dive into the science, our guide on what nitric oxide is and how it works covers the full picture.
But here is the problem most people over 40 do not realize: your body produces less nitric oxide with every passing decade. And the decline is not subtle.
What causes nitric oxide levels to drop?
Several factors reduce your body's ability to produce NO. Some are within your control. Others are not.
- Age: Research published in the Journal of Physiology shows that endothelial NO production declines progressively after age 40, with some estimates suggesting a 50% reduction by age 70 (Seals et al., 2011). This is one of the key reasons cardiovascular risk rises with age.
- Sedentary lifestyle: Physical activity stimulates the endothelium (the inner lining of your blood vessels) to produce nitric oxide. Without regular movement, that stimulus disappears. A 2003 study in Circulation confirmed that aerobic exercise significantly enhances endothelial NO synthesis in previously sedentary adults (Green et al., 2003).
- Poor diet — especially low vegetable intake: Your body converts dietary nitrates (found in beets, leafy greens, and other vegetables) into nitric oxide through the nitrate-nitrite-NO pathway. A diet low in these foods starves that pathway of raw material.
- Antiseptic mouthwash use: This one surprises most people. The oral bacteria on your tongue are essential for converting dietary nitrate into nitrite — a critical step in NO production. Antibacterial mouthwash kills those bacteria. A study in Free Radical Biology and Medicine found that mouthwash use reduced plasma nitrite levels by 25% and was associated with higher blood pressure readings (Kapil et al., 2013).
- Chronic stress and poor sleep: Both contribute to oxidative stress, which breaks down nitric oxide faster than your body can produce it.
- Smoking and excessive alcohol: Both damage the endothelial cells that produce NO, reducing output over time.
The reality is that most adults over 40 are dealing with more than one of these factors simultaneously.
What are the signs your nitric oxide levels might be low?
Low nitric oxide does not show up on a standard blood test. Instead, it tends to reveal itself through a pattern of symptoms that people often attribute to "just getting older." Here are the most common signs.
Persistent fatigue that caffeine does not fix
When NO levels drop, blood vessels cannot dilate as efficiently, meaning less oxygen reaches your muscles and organs. The result is a bone-deep tiredness that another cup of coffee will not solve — because the issue is not alertness. It is oxygen delivery.
Cold hands and feet
Poor peripheral circulation is one of the earliest and most noticeable signs of reduced NO. If your fingers and toes are consistently cold — even in a warm room — it may indicate your blood vessels are not relaxing and expanding the way they should.
Slow exercise recovery
Nitric oxide supports blood flow to muscles during and after exercise. When levels are low, metabolic waste products (like lactate) clear more slowly, and nutrient delivery to damaged muscle fibers is reduced. The result: you stay sore longer and bounce back slower than you used to.
Brain fog and difficulty concentrating
Your brain receives roughly 20% of your body's blood supply. Reduced NO means reduced cerebral blood flow, which can manifest as difficulty focusing, mental sluggishness, or feeling like you are "thinking through mud." A 2017 review in Neuroscience & Biobehavioral Reviews highlighted nitric oxide's role in cerebrovascular regulation and cognitive function (Toda et al., 2009).
Erectile dysfunction
For men, this is often the first clinical sign. Erections depend directly on nitric oxide — it is the molecule that triggers smooth muscle relaxation in penile blood vessels, allowing blood flow to increase. In fact, medications like sildenafil (Viagra) work by amplifying the NO signaling pathway. Erectile difficulty can be an early indicator of broader endothelial dysfunction.
Elevated blood pressure readings
When blood vessels cannot properly relax, resistance to blood flow increases, and blood pressure rises. While many factors contribute to elevated blood pressure, declining NO production is recognized as a contributing mechanism, particularly in age-related hypertension.
Slow wound healing
Adequate blood flow delivers immune cells and nutrients to injury sites. If cuts or bruises seem to take longer to heal than they used to, reduced circulation from low NO may be a contributing factor.
Can you test your nitric oxide levels at home?
Not reliably. There is no direct consumer test for nitric oxide levels, and here is why: NO is an extremely short-lived molecule. It exists in the body for only a few seconds before breaking down into nitrate and nitrite.
You may see saliva test strips marketed for "nitric oxide testing." These strips measure salivary nitrite — not nitric oxide itself. They can give a rough indication of whether your body is converting dietary nitrates through the oral pathway, but they do not measure actual NO levels in your bloodstream or tissues.
Clinical researchers measure NO indirectly through flow-mediated dilation (FMD) tests using specialized ultrasound equipment. This is not available as a consumer test.
The practical approach: Rather than chasing a test number, pay attention to the symptom pattern. If you are experiencing several of the signs above — especially fatigue, cold extremities, and slow recovery — and you are over 40, declining NO is worth discussing with your doctor.
How can you support healthy nitric oxide levels naturally?
The good news is that NO production responds well to lifestyle changes. Your body has two distinct pathways for producing nitric oxide, and you can support both of them.
Eat nitrate-rich foods
The nitrate-nitrite-NO pathway converts dietary nitrates from food into nitric oxide. The strongest food sources include:
- Beetroot — one of the most concentrated natural sources of dietary nitrate
- Arugula (rocket) — actually contains more nitrate per gram than beets
- Spinach, kale, and Swiss chard
- Celery and radishes
- Pomegranate — supports NO through antioxidant protection rather than nitrate content
A 2013 meta-analysis published in the Journal of Nutrition found that dietary nitrate from beetroot juice was associated with modest but consistent reductions in systolic blood pressure, typically in the range of 3–5 mmHg (Siervo et al., 2013).
Move your body regularly
Aerobic exercise is one of the most effective natural NO boosters. When blood flows faster during exercise, it creates shear stress on vessel walls, triggering the enzyme eNOS (endothelial nitric oxide synthase) to produce more NO.
You do not need extreme exercise. Brisk walking, cycling, or swimming for 20–30 minutes most days can meaningfully support NO production.
Breathe through your nose
Your paranasal sinuses produce nitric oxide continuously. Nasal breathing delivers that NO directly to your lungs, improving oxygen absorption. Mouth breathing bypasses this entirely.
Reconsider antiseptic mouthwash
As noted above, antibacterial mouthwash can significantly reduce the oral bacteria your body relies on for the nitrate-nitrite conversion pathway. If you are using mouthwash daily and experiencing symptoms of low NO, it may be worth discussing alternatives with your dentist.
Consider targeted supplementation
If dietary changes alone are not enough — especially for adults over 40 whose enzymatic NO production is already declining — supplementation can help support both pathways.
The two main supplement approaches for nitric oxide support are:
- Dietary nitrate sources (like beetroot extract) — these feed the nitrate-nitrite-NO pathway for a relatively fast-acting boost in NO availability.
- NO precursors (like L-citrulline and L-arginine) — L-citrulline is recycled in the body to continuously produce L-arginine, which the eNOS enzyme converts into nitric oxide. This provides more sustained support.
A formula that combines both approaches — dietary nitrate plus NO precursors — addresses both pathways simultaneously. Zenith Formulas Beetroot Gummies, for example, pair 100mg of 10:1 beetroot extract (equivalent to 1,000mg of whole beet) with an L-citrulline and L-arginine blend, plus grape seed extract, vitamin C, and B12 for a dual-path approach to NO support. They are formulated in the USA and third-party tested.
When should you see a doctor?
Lifestyle changes and supplementation can support healthy NO levels, but some symptoms warrant professional evaluation. See your doctor if you are experiencing:
- Consistently elevated blood pressure readings (above 130/80 mmHg on multiple measurements)
- Chest pain, tightness, or shortness of breath — these require immediate medical attention
- Erectile dysfunction that persists — this can be an early warning sign of cardiovascular disease and should be evaluated
- Sudden changes in exercise tolerance — if you are becoming winded during activities that were previously easy
- Numbness or tingling in extremities — this may indicate circulation issues that go beyond NO levels
- Fatigue accompanied by other symptoms such as unexplained weight changes, hair loss, or chronic infections — these may point to thyroid issues, anemia, or other conditions unrelated to NO
Many of these symptoms overlap with other health conditions. A healthcare provider can help rule out other causes and determine the right course of action for your situation.
Important: If you are taking blood pressure medication, blood thinners, or medications for erectile dysfunction, consult your doctor before adding any supplement to your routine. Some supplements that support NO production may interact with these medications.
Frequently asked questions
What is the fastest way to increase nitric oxide naturally?
The fastest dietary approach is consuming nitrate-rich foods like beetroot or beetroot juice — the nitrate-nitrite-NO conversion can begin within 1–3 hours. For immediate NO production, aerobic exercise activates the enzymatic pathway within minutes.
Does nitric oxide decline with age?
Yes. Research shows that endothelial NO production decreases progressively starting around age 40, with significant declines by age 60–70 — driven by reduced eNOS enzyme activity and increased oxidative stress (Seals et al., 2011).
Can mouthwash really affect nitric oxide levels?
Yes. Antibacterial mouthwash kills the oral bacteria responsible for converting dietary nitrate into nitrite — a critical intermediate step in NO production. A study by Kapil et al. (2013) found that antiseptic mouthwash reduced plasma nitrite by approximately 25% and was associated with measurably higher blood pressure.
Are there any blood tests for nitric oxide?
No standard consumer blood test measures NO directly because the molecule degrades within seconds. Researchers use indirect markers like plasma nitrite levels or flow-mediated dilation (FMD) tests. Consumer saliva test strips measure only salivary nitrite — not a reliable measure of overall NO status.
What foods are highest in nitric oxide?
Foods do not contain nitric oxide directly — they contain nitrates, which your body converts into NO. The highest nitrate foods include arugula, beetroot, spinach, celery, and radishes. Dark chocolate and pomegranate support NO through different mechanisms (antioxidant protection of existing NO rather than nitrate conversion).
Can exercise alone raise nitric oxide levels?
Regular aerobic exercise is one of the most effective ways to increase NO production. Exercise creates shear stress on blood vessel walls, which stimulates eNOS enzyme activity. However, for adults over 40 with age-related decline, combining exercise with dietary nitrate intake tends to produce better results than exercise alone.
Is low nitric oxide dangerous?
Low NO itself is not a diagnosis — it is a contributing factor. Reduced nitric oxide availability is associated with endothelial dysfunction, which is recognized as an early stage in cardiovascular risk development. It is one piece of a larger picture that includes blood pressure, cholesterol, and lifestyle factors.
How long does it take for nitric oxide levels to improve?
Dietary nitrate from beetroot can produce measurable changes in plasma nitrite within 1–3 hours. However, sustained improvement in endothelial function from lifestyle changes typically takes 4–8 weeks of daily effort before most people notice meaningful symptom changes.
Sources
- Seals, D.R., Jablonski, K.L., & Donato, A.J. (2011). Aging and vascular endothelial function in humans. Clinical Science, 120(9), 357–375. PubMed
- Green, D.J., Maiorana, A., O'Driscoll, G., & Taylor, R. (2003). Effect of exercise training on endothelium-derived nitric oxide function in humans. The Journal of Physiology, 561(1), 1–25. PubMed
- Kapil, V., Haydar, S.M.A., Pearl, V., Lundberg, J.O., Weitzberg, E., & Ahluwalia, A. (2013). Physiological role for nitrate-reducing oral bacteria in blood pressure control. Free Radical Biology and Medicine, 55, 93–100. PubMed
- Siervo, M., Lara, J., Ogbonmwan, I., & Mathers, J.C. (2013). Inorganic nitrate and beetroot juice supplementation reduces blood pressure in adults: a systematic review and meta-analysis. The Journal of Nutrition, 143(6), 818–826. PubMed
- Toda, N., Ayajiki, K., & Okamura, T. (2009). Cerebral blood flow regulation by nitric oxide: recent advances. Pharmacological Reviews, 61(1), 62–97. PubMed
Last updated: March 2026
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and does not constitute medical advice. Consult your healthcare provider before beginning any supplement regimen.