TL;DR: Nitric oxide (NO) is a signaling molecule your body produces to relax blood vessels, support healthy circulation, and deliver oxygen to your muscles and brain. Your body makes it through two pathways — the L-arginine/eNOS enzyme pathway and the dietary nitrate pathway (found in foods like beetroot and leafy greens). NO levels naturally decline with age, but diet, exercise, and targeted supplementation can help maintain healthy production.
What Is Nitric Oxide?
Nitric oxide is a gas molecule made up of one nitrogen atom and one oxygen atom (NO). Your body produces it naturally, and it acts as a signaling molecule — meaning it tells your cells what to do.
For a focused look at this topic, see our caffeine-free NO gummies.Its most important job is vasodilation: relaxing the smooth muscle lining of your blood vessels so they widen and allow blood to flow more freely. This was considered such a significant discovery that the three scientists who identified nitric oxide's role in cardiovascular signaling — Robert Furchgott, Louis Ignarro, and Ferid Murad — were awarded the Nobel Prize in Physiology or Medicine in 1998.
Think of nitric oxide as a traffic controller for your circulatory system. When NO levels are healthy, blood flows smoothly to your organs, muscles, and brain. When levels drop, that traffic slows down — and you start to feel it.
Why Is Nitric Oxide Important for Your Health?
Nitric oxide plays a role in nearly every major system in your body. Here are the areas where research has found the strongest connections.
Blood Pressure and Cardiovascular Health
Nitric oxide signals the smooth muscle cells in your artery walls to relax, which widens your blood vessels and supports healthy blood pressure. A review published in Biochemical and Biophysical Research Communications confirmed that impaired NO bioavailability is closely linked to endothelial dysfunction — a precursor to cardiovascular issues (Tousoulis et al., 2020).
This is why so much cardiovascular research focuses on maintaining healthy NO levels as we age.
For a focused look at this topic, see our plant-based nitric oxide gummies.Circulation and Blood Flow
By widening blood vessels, nitric oxide helps deliver oxygen and nutrients to tissues throughout your body. Healthy circulation supports everything from wound healing to organ function to how warm your hands and feet feel on a cold day.
Exercise Performance and Recovery
During physical activity, your muscles need more oxygen. Nitric oxide helps meet that demand by increasing blood flow to working muscles. Research published in the Journal of Applied Physiology found that dietary nitrate supplementation — which increases NO availability — improved exercise efficiency and extended time to exhaustion in healthy adults (Bailey et al., 2009).
For athletes and active adults, maintaining healthy NO levels may support endurance, oxygen delivery, and post-exercise recovery.
Brain Function and Mental Clarity
Your brain consumes roughly 20% of your body's oxygen supply, despite being only about 2% of your body weight. Nitric oxide helps regulate cerebral blood flow, ensuring your brain gets the oxygen it needs for focus, memory, and cognitive processing.
A study in the Journal of Cerebral Blood Flow & Metabolism found that NO-mediated vasodilation plays a key role in matching blood supply to neural activity — essentially making sure blood goes where your brain needs it most (Attwell et al., 2010).
Immune System Function
Nitric oxide also plays a role in immune defense. Certain immune cells (macrophages) produce NO in high concentrations to help neutralize pathogens. While this is a different mechanism than the cardiovascular role, it highlights how broadly important this molecule is across your body's systems.
What Happens When Nitric Oxide Levels Are Low?
Because nitric oxide is involved in so many bodily functions, low levels can show up in multiple ways. Common signs associated with reduced NO availability include:
- Persistent fatigue or low energy — even with adequate sleep
- Feeling winded easily — during activities that didn't used to be difficult
- Cold hands and feet — a sign of reduced peripheral circulation
- Slower recovery after exercise — muscles take longer to bounce back
- Difficulty concentrating or mental fog — less blood flow to the brain
- Elevated blood pressure readings — blood vessels aren't relaxing as efficiently
Age-Related Decline
Here's the part nobody wants to hear: your body's ability to produce nitric oxide declines with age. Research published in The Journals of Gerontology found that NO production decreases significantly after age 40, with endothelial function declining progressively each decade (Seals et al., 2011).
This decline is gradual, but it compounds. By your 50s and 60s, your body may be producing substantially less NO than it did in your 30s. This is one of the reasons cardiovascular health becomes a bigger concern with age — and why supporting NO production through diet and lifestyle becomes more important over time.
How Does Your Body Produce Nitric Oxide?
Your body has two distinct pathways for producing nitric oxide. Understanding both is important because they work differently — and supporting both gives you the most complete coverage.
Pathway 1: The L-Arginine/eNOS Pathway (Enzyme-Dependent)
This is your body's primary NO production method. Here's how it works:
- The amino acid L-arginine circulates in your bloodstream.
- An enzyme called endothelial nitric oxide synthase (eNOS), located in the lining of your blood vessels, converts L-arginine into nitric oxide.
- The NO is released, signals the surrounding smooth muscle cells to relax, and your blood vessels widen.
This pathway works well in younger, healthy adults. But eNOS enzyme activity declines with age, oxidative stress, and poor diet — which is why relying solely on this pathway becomes less effective over time.
Key player: L-citrulline. While L-arginine is the direct precursor, the amino acid L-citrulline is actually recycled by your kidneys back into L-arginine, creating a sustained supply. This is why many researchers consider L-citrulline supplementation more effective than L-arginine alone for long-term NO support.
Pathway 2: The Nitrate-Nitrite-NO Pathway (Diet-Dependent)
This second pathway doesn't depend on enzymes at all — it runs on the food you eat. Here's the process:
- You eat foods rich in dietary nitrates — beetroot, spinach, arugula, and other leafy greens are among the richest sources.
- Bacteria on the back of your tongue convert those nitrates into nitrites.
- In the acidic environment of your stomach (and in your bloodstream), nitrites are further converted into nitric oxide.
This pathway is especially important as you age because it works independently of the eNOS enzyme. Even when your enzyme-dependent pathway slows down, you can still produce nitric oxide through dietary nitrates.
A landmark study published in Hypertension (a journal of the American Heart Association) demonstrated that dietary nitrate from beetroot juice supported healthy blood pressure levels in adults, with effects observed within hours of consumption (Kapil et al., 2015).
Why both pathways matter: The enzyme pathway provides baseline NO production. The dietary nitrate pathway provides a backup — and for many adults over 40, it becomes the more reliable of the two. Supporting both pathways simultaneously is the most complete approach to maintaining healthy NO levels.
What Foods Naturally Boost Nitric Oxide?
Diet is one of the most effective ways to support nitric oxide production — particularly through the dietary nitrate pathway. The following foods are among the richest natural sources of NO-supporting compounds.
- Beetroot — One of the highest dietary nitrate sources studied. Both whole beets and beetroot juice have been extensively researched for their ability to support NO production and healthy circulation.
- Leafy greens — Spinach, arugula, kale, and Swiss chard are all rich in dietary nitrates. Arugula contains some of the highest nitrate concentrations of any vegetable.
- Citrus fruits — Oranges, lemons, and grapefruit are rich in vitamin C, which helps protect nitric oxide from being broken down by free radicals, extending its activity in your body.
- Pomegranate — Contains polyphenols that may help protect NO from oxidative degradation and support endothelial function.
- Dark chocolate — The flavanols in dark chocolate (70%+ cacao) have been shown to stimulate NO production in the endothelium. Look for minimally processed varieties.
- Garlic — May increase NO bioavailability by activating nitric oxide synthase. Aged garlic extract has the most research behind it.
- Nuts and seeds — Walnuts, almonds, and flaxseeds provide L-arginine, the direct precursor your body uses in the enzyme-dependent NO pathway.
Practical tip: Eating a combination of nitrate-rich vegetables (for the dietary pathway) and L-arginine-rich proteins and nuts (for the enzyme pathway) gives your body raw materials for both NO production routes.
What Supplements Support Nitric Oxide Production?
When diet alone isn't enough — or when you want targeted support — certain supplements have research backing their ability to support NO production.
- L-Citrulline — Converted to L-arginine in the kidneys, then used to produce NO via the eNOS enzyme. Research suggests L-citrulline raises blood arginine levels more effectively than taking L-arginine directly, because L-arginine is partially broken down during digestion before it reaches the bloodstream.
- L-Arginine — The direct precursor to NO in the enzyme-dependent pathway. Works best when combined with L-citrulline for sustained availability.
- Beetroot extract — Provides concentrated dietary nitrates that feed the nitrate-nitrite-NO pathway. Concentrated extracts (such as 10:1 ratios) deliver the equivalent of a large serving of whole beets in a smaller dose.
- Grape seed extract — Rich in polyphenols that may support endothelial function and help maintain healthy circulation. Some research suggests it works synergistically with nitrate-rich ingredients.
For those looking for a convenient option that covers both NO pathways, Zenith Formulas' Beetroot Gummies combine beetroot extract (100mg of 10:1 extract, equivalent to 1,000mg of whole beet) with L-citrulline and L-arginine in a single serving — formulated in the USA and designed to support both the dietary nitrate pathway and the enzyme-dependent pathway.
Regardless of which supplement you choose, look for products with transparent ingredient labels, third-party testing, and clearly stated dosages rather than proprietary blends.
How Can You Tell If Your Nitric Oxide Levels Are Low?
There is no standard blood test that directly measures nitric oxide levels. NO is a gas that breaks down within seconds of being produced, which makes it extremely difficult to measure in a clinical setting.
What doctors can measure are indirect markers:
- Blood pressure readings — Consistently elevated readings may indicate reduced NO-mediated vasodilation.
- Endothelial function tests — Specialized tests like flow-mediated dilation (FMD) can assess how well your blood vessels respond to changes in blood flow, which reflects NO activity.
- Nitrate/nitrite levels in blood or saliva — Some researchers measure these as proxies for NO production, though this isn't part of routine medical care.
For most people, the practical approach is to pay attention to the signs mentioned earlier — fatigue, poor circulation, exercise intolerance, brain fog — and talk to your doctor if you notice a pattern. Age is the single biggest risk factor: if you're over 40 and experiencing several of these signs, supporting NO production through diet and lifestyle is a reasonable step.
Does Nitric Oxide Help with Exercise Performance?
Yes — and this is one of the most well-researched areas of nitric oxide science. The connection between NO and exercise performance centers on three mechanisms:
Improved Oxygen Delivery
Nitric oxide widens blood vessels, allowing more oxygen-rich blood to reach working muscles during exercise. This can make the same level of effort feel slightly easier — or allow you to sustain a given intensity for longer.
Greater Exercise Efficiency
Research from the University of Exeter found that dietary nitrate supplementation reduced the oxygen cost of submaximal exercise — meaning subjects used less oxygen to perform the same amount of work. This translated to improved endurance and extended time to exhaustion (Bailey et al., 2009, Journal of Applied Physiology).
Faster Recovery
Better blood flow during and after exercise means nutrients and oxygen reach damaged muscle tissue more quickly, and metabolic waste products are cleared faster. While NO alone doesn't replace proper recovery practices (sleep, nutrition, rest days), it may support the body's natural repair processes.
These benefits apply across fitness levels — from recreational walkers to competitive endurance athletes. The research is strongest for aerobic activities like running, cycling, and swimming, where sustained blood flow has the biggest impact on performance.
Frequently Asked Questions
Is nitric oxide the same as nitrous oxide?
No. Nitric oxide (NO) is a signaling molecule your body produces naturally to regulate blood flow and immune function. Nitrous oxide (N₂O) is a completely different compound — commonly known as "laughing gas" — used in dentistry. They have different chemical structures and entirely different functions.
Can you take too much nitric oxide?
Your body regulates NO production tightly, so "overdosing" on nitric oxide itself isn't really possible through food or supplements. However, excessive intake of NO precursors like L-arginine can cause digestive discomfort in some people. Follow recommended serving sizes on any supplement and consult your doctor if you're on blood pressure medication or blood thinners.
How quickly do nitric oxide supplements work?
Dietary nitrate from beetroot can begin converting to NO within 2-3 hours of consumption. L-citrulline takes slightly longer as it must first convert to L-arginine. Most people who notice a difference report changes within 1-2 weeks of consistent daily use, though acute effects on blood flow can occur within hours.
Does mouthwash affect nitric oxide production?
Surprisingly, yes. The dietary nitrate pathway depends on bacteria on the back of your tongue to convert nitrates into nitrites. Antibacterial mouthwash kills these bacteria, which can reduce NO production from dietary sources. A study published in Free Radical Biology and Medicine found that antiseptic mouthwash use was associated with reduced nitrite levels and increased blood pressure (Kapil et al., 2013).
At what age does nitric oxide production start to decline?
Research suggests that NO production begins declining around age 30-40, with more noticeable decreases after 40. By age 70, some studies estimate NO production capacity may be reduced by 75% compared to young adults. This is a gradual process, not a sudden drop, and it can be influenced by diet, exercise, and overall cardiovascular health.
Can exercise increase nitric oxide levels?
Yes. Physical activity — especially aerobic exercise — stimulates eNOS enzyme activity, which increases NO production. This is one reason regular exercise supports healthy blood pressure and cardiovascular function. The shear stress of blood flowing faster through your vessels during exercise triggers your endothelium to produce more NO.
Are nitric oxide supplements safe to take with blood pressure medication?
Because NO-supporting supplements may influence blood vessel dilation, they could potentially interact with blood pressure medications. Always consult your healthcare provider before combining any supplement with prescription medication. This is especially important for people taking nitrates, PDE5 inhibitors, or antihypertensive drugs.
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 educational purposes only and is not a substitute for professional medical advice. Consult your healthcare provider before making changes to your supplement regimen.