The question of which foods are high in Nitric Oxide often stems from a common chemical misunderstanding. Nitric Oxide, or NO, is a simple, highly reactive gas that the body produces internally, not a compound found pre-formed in food. Foods instead contain high amounts of nitrates and nitrites, which are the precursor molecules your body uses to generate beneficial Nitric Oxide. It is also important to recognize that this molecule is distinct from Nitrous Oxide (\(N_2O\)), or “laughing gas,” which has no nutritional connection to these foods. Understanding the distinction between these compounds is the first step toward harnessing the power of your diet to improve circulation and overall health.
Nitric Oxide: Its Essential Role in the Body
Nitric Oxide is a gaseous signaling molecule that plays an important role across multiple bodily systems. Its most recognized function is as a potent vasodilator, meaning it causes the smooth muscle walls of blood vessels to relax. This relaxation leads to the widening of arteries and arterioles, which directly improves blood flow throughout the circulatory system. Improved blood flow subsequently regulates blood pressure and supports better oxygen and nutrient delivery to working muscles and tissues. Beyond its vascular effects, NO is also involved in neurological functions, acting as a neurotransmitter to aid in nerve signaling.
The Nitrate-to-Nitric Oxide Conversion Pathway
The body uses an elegant, two-step process to convert the nitrates consumed in food into usable Nitric Oxide. This pathway is independent of the body’s primary, internal system for NO production. Once ingested, dietary nitrates are rapidly absorbed into the bloodstream before being actively concentrated in the salivary glands, raising saliva concentration by 10 to 20 times.
The second step occurs in the mouth, where specialized oral bacteria contain nitrate reductase enzymes. These bacteria reduce the nitrate (\(NO_3\)) in the saliva to nitrite (\(NO_2\)). When this nitrite-rich saliva is swallowed, it reacts with the acidic environment of the stomach, converting it into the final, biologically active Nitric Oxide molecule.
Primary Dietary Sources of Nitrates
The foods highest in nitrates are overwhelmingly vegetables, specifically leafy greens and root vegetables. Arugula consistently ranks as one of the richest whole-food sources, often containing around 480 milligrams per 100 grams. This high concentration makes it highly effective for rapidly boosting Nitric Oxide production.
Dark, leafy greens also contain significant levels of this precursor molecule. Spinach can contain over 250 milligrams of nitrates per 100 grams, and Swiss chard and kale are also excellent sources. Regularly incorporating these greens supports cardiovascular health through the nitrate pathway.
Beetroots and their juice are the most studied foods for their NO-boosting properties. Beet juice is a potent source, often capable of significantly increasing plasma nitrite levels within hours of consumption. Celery, another root vegetable, also provides more than 250 milligrams of nitrates per 100 grams.
Supporting Foods: Amino Acids for Nitric Oxide Synthesis
The body also has a distinct, internal system for producing Nitric Oxide using specific amino acids. This endogenous pathway relies on the amino acid L-arginine, which is converted to NO and L-citrulline through a reaction catalyzed by the enzyme Nitric Oxide Synthase (NOS). L-arginine is considered a semi-essential amino acid found naturally in protein-rich sources like nuts, seeds, seafood, and meat proteins.
A more direct way to support this pathway is by consuming L-citrulline, which is a precursor to L-arginine. Watermelon is a particularly notable source of L-citrulline, and when consumed, the amino acid is efficiently converted into L-arginine in the kidneys.
Maximizing Nitric Oxide Absorption Through Diet
Optimizing the conversion of dietary nitrates requires attention to preparation and consumption methods.
Cooking Methods
Boiling high-nitrate vegetables can reduce their nitrate content substantially, with losses ranging from 22% to over 75% as the nitrate leaches into the cooking water. Steaming or quickly stir-frying is preferable, as these methods lead to much lower nitrate loss. This allows for better retention of the precursor molecules.
Consumption and Chewing
The mechanical action of eating plays a direct role in the initial conversion step. Thorough chewing enhances salivary flow, which mixes the concentrated nitrate in the saliva with the nitrate-reducing bacteria on the tongue. This simple action can lead to a faster and higher initial spike in Nitric Oxide metabolites soon after consumption.
Inhibitors
Using antiseptic mouthwash can severely disrupt the conversion process. Mouthwash indiscriminately kills the beneficial oral bacteria required for the critical nitrate-to-nitrite conversion.