Several things increase nitric oxide in your body, and they work through surprisingly different pathways. Some trigger your blood vessels to produce it directly, others supply the raw materials your body converts into it, and a few protect the nitric oxide you already have from breaking down too quickly. Understanding these pathways helps you stack multiple strategies for the biggest effect.
Nitrate-Rich Vegetables
The most well-studied dietary strategy is eating vegetables high in nitrate, a compound your body converts into nitric oxide through a two-step process. Spinach, arugula, and beets are among the richest sources, with nitrate concentrations ranging from 250 to 700 mg per kilogram. Celery, lettuce, and radishes also contribute meaningful amounts, though at lower concentrations.
Here’s where it gets interesting: you can’t do this conversion on your own. Bacteria living on the back of your tongue reduce dietary nitrate into nitrite using specialized enzymes. That nitrite then enters your bloodstream and gets converted into nitric oxide in your tissues. This is called the enterosalivary pathway, and it’s essential. Without those oral bacteria doing the first step, the nitrate in your salad does very little.
This has a practical implication that catches many people off guard. Antibacterial mouthwash can lower oral nitrate reduction by 90% and reduce plasma nitrite levels by up to 25%, with a small but measurable increase in blood pressure of 2 to 3.5 mmHg. In clinical trials, mouthwash use completely abolished the blood pressure benefits of nitrate supplementation. Chronic mouthwash use has even been linked to increased risk of prediabetes and hypertension. If you’re eating beets for your blood pressure, rinsing with chlorhexidine afterward is working against you.
Beetroot Juice Timing and Results
Beetroot juice is the most popular concentrated source of dietary nitrate, and the timing matters. Plasma nitrite levels peak 2 to 3 hours after drinking it, so if you’re using it before exercise or for blood pressure support, that’s your window. A meta-analysis of beetroot juice supplementation found it reduced systolic blood pressure by an average of 3.55 mmHg and diastolic pressure by 1.32 mmHg across studies lasting 2 to 56 days. That’s a modest but clinically relevant drop, especially for people already dealing with elevated blood pressure.
L-Citrulline Outperforms L-Arginine
Your body makes nitric oxide from the amino acid L-arginine using an enzyme in your blood vessel walls. So it seems logical that taking L-arginine as a supplement would boost nitric oxide. The problem is that enzymes in your gut and liver break down most of the L-arginine you swallow before it ever reaches your bloodstream. This extensive first-pass metabolism limits how much actually becomes available for nitric oxide production.
L-citrulline, a different amino acid found naturally in watermelon, takes a detour around that problem. Your gut absorbs it easily, and your kidneys then convert it into L-arginine. A study published in the British Journal of Clinical Pharmacology found that oral L-citrulline raised plasma L-arginine levels significantly more than taking L-arginine itself, at every dose tested. The peak arginine concentration after 3 grams of L-citrulline twice daily was dramatically higher than after equivalent L-arginine doses, whether immediate or sustained release formulations.
For athletic performance, citrulline malate (L-citrulline bonded to malic acid) is the most commonly studied form. The typical dose in exercise research is a single 8-gram dose taken before training. Some studies have used pure L-citrulline at 1.5 to 3 grams twice daily for sustained blood flow support rather than acute performance.
Exercise and Blood Flow
Physical activity is one of the most powerful triggers for nitric oxide production, and the mechanism is purely mechanical. When your heart rate increases during exercise, blood moves faster through your vessels. This faster flow creates a dragging force called shear stress along the inner walls of your arteries. Cells lining those walls sense the force and activate an enzyme that produces nitric oxide on the spot. The nitric oxide then relaxes the surrounding muscle in the vessel wall, widening the artery and allowing more blood through.
This is one reason regular exercise lowers blood pressure over time. Repeated bouts of shear stress train your blood vessels to produce nitric oxide more efficiently. Both aerobic exercise (running, cycling, swimming) and resistance training generate this effect, though sustained aerobic activity creates the most consistent shear stress. Even brisk walking counts.
Sunlight on Your Skin
Your skin stores nitric oxide in inactive forms, including nitrite and compounds called S-nitrosothiols. When UVA light from sunlight hits your skin, it breaks these stored compounds apart, freeing active nitric oxide. Some of that nitric oxide diffuses into the capillaries beneath your skin and enters your bloodstream, raising levels of circulating nitroso compounds and lowering blood pressure.
Research published in Circulation Research confirmed this mechanism in healthy volunteers. Whole-body UVA exposure significantly increased nitric oxide levels in the skin and blood while producing a measurable drop in blood pressure. The effect was specifically tied to UVA wavelengths acting on these photosensitive nitrogen compounds, not to heat or vitamin D production (which is driven by UVB). This may partly explain why blood pressure tends to be lower in summer months and in populations closer to the equator.
Breathing Through Your Nose
Your paranasal sinuses continuously produce nitric oxide and release it into your nasal airways. When you breathe through your nose, you inhale this self-generated nitric oxide with each breath, delivering it directly to your lungs. There it acts as a vasodilator, opening up blood vessels in the lung tissue and improving oxygen uptake.
Studies on healthy subjects found that blood oxygen levels were about 10% higher during nasal breathing compared to mouth breathing. In intubated hospital patients, who can’t breathe through their nose, adding air sampled from the patient’s own nasal passages to their ventilator supply increased arterial oxygen levels by 18% and reduced pulmonary vascular resistance by 11% in some patients. Nasal breathing during exercise and throughout the day is a simple, free way to keep nitric oxide flowing to your lungs.
Vitamin C and Antioxidant Protection
Producing more nitric oxide only helps if it survives long enough to do its job. Free radicals, particularly a type called superoxide, react with and destroy nitric oxide almost instantly. This is why oxidative stress is so damaging to cardiovascular health: it’s not just that free radicals harm cells directly, but that they eliminate the nitric oxide your body depends on to keep blood vessels relaxed.
Vitamin C acts as a scavenger that neutralizes superoxide before it can reach nitric oxide. It also appears to increase the activity of the enzyme responsible for nitric oxide production in blood vessel walls. Animal research has shown that vitamin C supplementation both prevents the oxidative destruction of nitric oxide and increases its overall availability, with measurable effects on blood pressure. Eating vitamin C-rich foods (citrus, bell peppers, strawberries, broccoli) alongside nitrate-rich vegetables creates a complementary effect: one pathway supplies the raw material, the other protects the finished product.
Stacking Multiple Strategies
These pathways are largely independent, which means combining them can produce additive effects. A practical approach might look like this:
- Diet: Regular intake of leafy greens, beets, and watermelon to supply both nitrate and citrulline
- Exercise: Consistent aerobic activity to stimulate vessel-wall production
- Oral health: Avoiding antibacterial mouthwash to preserve the bacteria that activate dietary nitrate
- Breathing: Nasal breathing to deliver sinus-produced nitric oxide to the lungs
- Sunlight: Moderate skin exposure to mobilize stored nitric oxide
- Antioxidants: Vitamin C-rich foods to prevent nitric oxide breakdown
No single strategy is a silver bullet. But because each one works through a different mechanism, they complement rather than compete with each other. The dietary nitrate pathway depends on oral bacteria. Exercise depends on mechanical forces. Sunlight depends on stored compounds in skin. Stacking even a few of these gives your body multiple routes to keep nitric oxide levels where they need to be.