You can increase nitric oxide naturally through a combination of dietary changes, exercise, sunlight exposure, and even the way you breathe. Nitric oxide is a signaling molecule your body produces to relax blood vessels, improve circulation, and regulate blood pressure. Because it breaks down within seconds of being made, keeping levels high requires a steady supply of raw materials and the right conditions for your body to produce and protect it.
Eat High-Nitrate Vegetables
The most direct dietary route to higher nitric oxide is eating vegetables rich in inorganic nitrate. Your body converts dietary nitrate into nitrite (with help from bacteria on your tongue), then into nitric oxide in your bloodstream and tissues. The vegetables with the highest nitrate concentrations per 100 grams are radish (625 mg), beetroot (495 mg), tarragon (424 mg), lettuce (365 mg), mint (279 mg), and celery (261 mg).
Beetroot gets the most attention because of the research behind it. In a study published in Hypertension, a dose of roughly 1,500 mg of nitrate (equivalent to about 300 grams of beetroot or a large glass of beet juice) lowered systolic blood pressure by up to 9.4 mmHg and diastolic pressure by 6 mmHg, peaking around 2 to 6 hours after ingestion. The effect was dose-dependent: smaller amounts still worked but produced smaller reductions. Even a dose around 750 mg of nitrate showed measurable benefits.
One practical detail worth knowing: antibacterial mouthwash can blunt this pathway. The bacteria on your tongue that convert nitrate to nitrite are essential to the process. If you kill them off, you short-circuit the conversion before it starts.
Cocoa Flavanols and Blood Flow
Dark chocolate and cocoa powder contain flavanols that stimulate your blood vessel lining to produce more nitric oxide. In a trial involving smokers (who typically have poor blood vessel function), consuming cocoa with 176 to 185 mg of flavanols significantly improved flow-mediated dilation, a measure of how well arteries expand in response to increased blood flow. The improvement appeared within two hours and was dose-dependent, though doubling the dose beyond that range didn’t add further benefit.
To put that in practical terms, around 175 mg of cocoa flavanols appears to be a threshold for meaningful vascular effects. That’s roughly 10 to 15 grams of natural cocoa powder (not Dutch-processed, which strips out most flavanols) or a small serving of high-percentage dark chocolate. Milk chocolate and most commercial cocoa mixes contain far less.
Exercise and Blood Vessel Training
Aerobic exercise is one of the most potent ways to increase your body’s nitric oxide production over time. When you exercise, blood moves faster through your arteries, creating physical friction against the vessel walls called shear stress. This mechanical force triggers the cells lining your blood vessels to produce more of the enzyme responsible for making nitric oxide.
Research from the American Heart Association found that four weeks of regular exercise doubled the amount of this enzyme in artery walls and quadrupled its activation level. The result was a 56% improvement in how well arteries dilated in response to signals. This study involved patients with coronary artery disease exercising on rowing and cycling machines for about 10 minutes each, three times daily, which suggests you don’t need extreme intensity to see results. Consistent moderate effort, repeated over weeks, remodels how your blood vessels function at a molecular level.
The key factor is regularity. Each exercise session creates a temporary spike in shear stress. Repeated over time, your blood vessels adapt by permanently upregulating their nitric oxide production machinery.
Sunlight on Your Skin
Your skin stores nitric oxide in a form that UVA light can release directly into your bloodstream. This process is entirely separate from the enzyme-driven production that happens inside blood vessels. UVA radiation penetrates the upper layers of skin and liberates pre-formed nitric oxide stores, with the largest pool sitting in the epidermis.
In a study of 24 healthy volunteers, UVA exposure lowered blood pressure with a corresponding rise in circulating nitrite levels. The effect was independent of dietary nitrate intake, meaning it works through a distinct mechanism. This helps explain why blood pressure tends to be lower in summer and in populations closer to the equator. Even moderate sun exposure on uncovered arms and legs may contribute to nitric oxide availability, though the exact duration needed varies with skin type and UV intensity.
Breathe Through Your Nose
Your paranasal sinuses continuously produce nitric oxide at concentrations far higher than what exists in your lungs. Breathing through your nose pulls this gas down into your airways and lungs, where it helps dilate blood vessels and improve oxygen uptake. In tracheotomized patients (who provided researchers a way to measure air from different routes independently), nasal breathing delivered nitric oxide at 35 parts per billion during normal tidal breathing, compared to just 7 ppb through the mouth and 3 ppb from the trachea alone. During controlled inhalation, nasal breathing pulled in 64 ppb versus 11 ppb for oral breathing.
This is a surprisingly simple intervention. If you habitually breathe through your mouth, especially during sleep or light activity, switching to nasal breathing gives your lungs a consistent dose of locally produced nitric oxide that mouth breathing simply bypasses.
L-Citrulline Over L-Arginine
L-arginine is the direct building block your body uses to make nitric oxide, but taking it as a supplement is less efficient than you might expect. About 40% of oral L-arginine gets broken down during its first pass through the gut, and the liver removes another 15% from circulation. That leaves a relatively small fraction available to your blood vessels.
L-citrulline, found naturally in watermelon, takes an indirect route. Your kidneys convert it into L-arginine, but because citrulline bypasses the gut and liver metabolism that destroys arginine, it actually raises blood levels of arginine more effectively. Citrulline also produces a slower, longer-lasting elevation that stays high for several hours, while arginine spikes faster but drops off quickly. Research in healthy males showed that combining both produced the fastest initial rise in plasma arginine, while citrulline alone was better for sustained availability.
If you prefer food sources, watermelon is the richest natural source of citrulline, with the highest concentrations in the rind.
Protect What Your Body Makes
Producing nitric oxide is only half the equation. Once made, it’s rapidly destroyed by reactive oxygen species, the same free radicals involved in oxidative stress. Under conditions of high oxidative stress, particularly when LDL cholesterol becomes oxidized, these reactive molecules degrade nitric oxide before it can do its job.
Vitamins C and E work together to counteract this. Vitamin E reduces free radical damage and protects the cells lining your blood vessels. Vitamin C scavenges free radicals directly and also stabilizes a cofactor that the nitric oxide-producing enzyme needs to function properly. Without adequate vitamin C, that enzyme can actually start producing harmful oxidants instead of nitric oxide, a process called “uncoupling.” A trial in children with high cholesterol found that the combination of vitamins C and E improved endothelial function, with the protective effects greater together than either vitamin alone.
Eating a diet rich in colorful fruits and vegetables covers both vitamins along with other antioxidants. Bell peppers, citrus, strawberries, and kiwi are particularly high in vitamin C. Nuts, seeds, and avocados are strong sources of vitamin E.