No food actually contains nitric oxide gas, which breaks down in seconds. Instead, your body makes nitric oxide from two types of compounds found in food: nitrates and amino acids. Eating the right foods gives your body the raw materials to produce nitric oxide on its own, which relaxes blood vessels, lowers blood pressure, and improves exercise performance. Here’s what to eat and how the process works.
How Your Body Makes Nitric Oxide From Food
Your body converts dietary nitrates into nitric oxide through a surprisingly indirect route that depends on bacteria living in your mouth. When you eat nitrate-rich vegetables, about 25% of that nitrate gets concentrated in your saliva. Bacteria on your tongue then convert salivary nitrate into nitrite, which you swallow. Once nitrite reaches your stomach and bloodstream, it’s further reduced into nitric oxide in your blood vessels and tissues.
This process has a practical implication worth knowing: antibacterial mouthwash can disrupt it. Studies show that antiseptic mouthwash blunts the conversion of nitrate to nitrite in the mouth, raises blood pressure, and increases blood glucose levels. If you’re eating beets and spinach specifically for cardiovascular benefits, frequent mouthwash use may be working against you.
Your body also produces nitric oxide from L-arginine, an amino acid found in protein-rich foods. This pathway works through an enzyme in the lining of your blood vessels and doesn’t depend on oral bacteria at all.
Vegetables With the Highest Nitrate Content
Leafy greens and root vegetables are the richest dietary sources of nitrates. Raw spinach contains roughly 296 mg of nitrate per 100 grams, making it one of the most concentrated sources you can eat. Cooked spinach retains most of that, dropping only slightly to about 274 mg per 100 grams. Arugula, celery, lettuce, and radishes are also well-known high-nitrate vegetables, though exact concentrations vary by growing conditions and soil.
Beets deserve special mention. Beetroot juice has become the most studied nitrate delivery method in exercise science, where researchers typically use doses of 6 to 12 mmol of nitrate to improve oxygen efficiency during physical activity. That said, nitrate concentrations vary widely between brands and batches of beetroot juice, so the amount listed on a label may not match what’s actually in the bottle. Whole beets, roasted or raw, provide nitrates along with fiber and other nutrients.
A normal daily nitrate intake from food is around 1.5 mmol. The doses used in performance studies are 2 to 20 times that amount, which gives you a sense of how much concentrated beetroot juice delivers compared to a typical meal.
Protein-Rich Foods That Supply L-Arginine
L-arginine is the amino acid your body uses to produce nitric oxide through a completely separate pathway from dietary nitrates. Seeds and nuts are especially rich sources. Pumpkin seed kernels top the list at about 1,520 mg of L-arginine per ounce. Black walnuts provide roughly 1,028 mg per ounce, while English walnuts (the common grocery store variety) contain about 647 mg per ounce.
Other strong sources include turkey breast, soybeans, chicken, lentils, and chickpeas. Because L-arginine is found in virtually all protein-containing foods, most people who eat adequate protein get enough of this amino acid without trying. The nitrate pathway from vegetables tends to be more impactful for boosting nitric oxide levels in people who already eat a normal amount of protein.
Watermelon and L-Citrulline
Watermelon is unique because it’s one of the few foods rich in L-citrulline, an amino acid your body converts into L-arginine, which then becomes nitric oxide. It’s an indirect route, but citrulline actually raises blood arginine levels more effectively than eating arginine directly, because arginine gets partially broken down in the gut before it reaches your bloodstream.
Both the flesh and the rind contain citrulline, and the comparison between them is surprisingly close. On a fresh weight basis, watermelon flesh contains about 1.0 to 3.5 mg of citrulline per gram, while the rind contains 0.8 to 1.5 mg per gram. Most people throw the rind away, but it’s edible. Some cultures pickle it or blend it into smoothies. The white part closest to the green skin contains most of the rind’s citrulline.
Dark Chocolate and Cocoa
Cocoa flavanols stimulate your blood vessels to produce more nitric oxide on their own, through a different mechanism than nitrates or arginine. Rather than providing a raw ingredient, flavanols activate the enzyme in your blood vessel lining that generates nitric oxide directly.
Research on smokers (who have impaired blood vessel function) found that consuming 176 to 185 mg of cocoa flavanols improved blood vessel dilation within two hours. That dose appeared to produce near-maximal effects, meaning doubling it didn’t add much additional benefit. In practical terms, 176 mg of flavanols is found in roughly 30 to 40 grams of high-quality dark chocolate (70% cocoa or higher), though flavanol content varies enormously by brand and processing method. Dutch-processed cocoa, for example, loses most of its flavanols during manufacturing.
Sunlight Triggers Nitric Oxide From Your Skin
Your skin stores nitric oxide in a stable, inactive form. When UVA light from the sun hits your skin, it breaks these compounds apart and releases free nitric oxide. Some of that nitric oxide enters your capillaries and circulates through your bloodstream.
This isn’t a trivial effect. In a study of healthy volunteers, whole-body UVA exposure lowered systolic and diastolic blood pressure by about 11% within 30 minutes, and the drop lasted up to an hour. This mechanism may partly explain why blood pressure tends to be lower in summer months and in populations living closer to the equator, independent of temperature.
How Cooking Affects Nitrate Levels
If you’re eating vegetables for their nitrate content, how you cook them matters. Boiling causes the greatest nitrate loss because nitrates are water-soluble and leach into the cooking water. Studies on potatoes found that boiling reduced nitrate content by roughly 30 to 50%, while steaming preserved significantly more, with losses closer to 10 to 15%. Frying caused the highest absolute losses in some samples, likely due to both heat and water evaporation concentrating the remaining compounds differently.
The practical takeaway: eat high-nitrate vegetables raw when you can (spinach in salads, raw beet slices), or steam them. If you boil greens, using the cooking liquid in a soup or sauce recaptures much of the lost nitrate.
Supplements Versus Whole Foods
Products marketed as “nitric oxide supplements” don’t contain nitric oxide itself, which has a half-life of only a few seconds and can’t survive in a capsule. These supplements typically contain L-arginine, L-citrulline, or beetroot powder as precursor compounds. Beetroot juice accounts for an estimated 80 to 90% of all dietary nitrate supplementation in research settings, which tells you something about which form has the most evidence behind it.
The main advantage of whole foods over supplements is consistency and additional nutrients. A bowl of spinach salad with beets, pumpkin seeds, and a square of dark chocolate covers all three nitric oxide pathways: nitrates from the vegetables, L-arginine from the seeds, and flavanol-triggered production from the chocolate. No single supplement replicates that combination.