No vegetable contains nitric oxide directly. Instead, certain vegetables are packed with nitrates, a compound your body converts into nitric oxide through a natural process involving bacteria in your mouth and acid in your stomach. The richest sources are leafy greens and root vegetables like arugula, beetroot, spinach, celery, and cress, some containing over 2,500 mg of nitrate per kilogram of fresh weight.
How Vegetables Become a Source of Nitric Oxide
When you eat a nitrate-rich vegetable, the nitrate enters your bloodstream and concentrates in your saliva. Bacteria living on the back of your tongue then convert that nitrate into nitrite using specialized enzymes that human cells lack. You swallow the nitrite, and once it hits the acidic environment of your stomach, it transforms into nitric oxide and related signaling molecules. This entire loop, sometimes called the enterosalivary pathway, means your oral bacteria are essential to the process. Antibacterial mouthwash can actually disrupt it.
Vegetables With the Most Nitrate
Vegetables vary enormously in nitrate content. Peas and Brussels sprouts, for instance, contain as little as 0.1 mg per 100 grams. Arugula (rocket) can reach 480 mg per 100 grams, making it one of the most concentrated sources available.
Researchers classify vegetable nitrate content into tiers based on milligrams per kilogram of fresh weight:
- Very high (over 2,500 mg/kg): arugula, beetroot, spinach, celery, cress, chervil, lettuce
- High (1,000 to 2,500 mg/kg): celeriac, Chinese cabbage, endive, fennel, leek, parsley
Spinach and arugula are often grouped together, but arugula tends to sit at the top of the range. Both deliver roughly 250 to 700 mg of nitrate per kilogram, though growing conditions, soil quality, and time of harvest shift these numbers considerably. Beetroot gets the most attention in supplement form because it’s easy to juice and has a mild, palatable flavor compared to bitter greens.
Blood Pressure and Heart Health
The nitric oxide produced from vegetable nitrates relaxes blood vessel walls, which lowers blood pressure. In one well-known study, a single dose of beetroot juice providing about 1,395 mg of nitrate reduced systolic blood pressure by 10 mmHg in healthy adults, with peak effects hitting around two and a half hours after drinking it. That’s a meaningful drop, comparable to what some blood pressure medications achieve.
Long-term results are more nuanced. A 16-week trial comparing high-nitrate and low-nitrate vegetable supplements in people with early-stage hypertension found no significant difference between the two groups for office blood pressure readings. This suggests that the acute blood pressure benefit is well established, but sustaining it over months through vegetables alone may depend on factors like overall diet quality and individual biology.
How Much You Need for Performance Benefits
Athletes and fitness enthusiasts use nitrate-rich vegetables, particularly beetroot juice, to improve endurance. The effective range in studies is roughly 300 to 1,000 mg of nitrate, taken two to three hours before exercise. At these doses, people use less oxygen during moderate to high-intensity activity, which translates to better endurance and delayed fatigue. Taking 5.5 mmol (about 340 mg) of nitrate daily for six consecutive days improved both exercise economy and time trial performance in one study.
These benefits show up most clearly in recreational or moderately trained athletes. Highly trained endurance athletes with very efficient cardiovascular systems tend to see smaller or no improvements. The sweet spot for exercise duration also matters: the clearest performance gains appear during efforts lasting roughly 10 to 17 minutes.
To put the dosage in practical terms, a 250 ml glass of concentrated beetroot juice typically delivers around 300 to 400 mg of nitrate. You could also reach that range with a large salad of arugula, spinach, and celery, though the concentration varies more with whole foods.
Cooking Methods Change Nitrate Levels
How you prepare your vegetables matters more than most people realize. Boiling causes the biggest losses because nitrates are water-soluble and leach into the cooking water. Research on potatoes found that boiling reduced nitrate content by nearly 70%, while steaming cut it by only 15%. If you’re eating these vegetables specifically for their nitrate content, steaming or eating them raw preserves far more of what you’re after.
Microwaving actually increased measurable nitrate and nitrite content in the same study, likely because no water is discarded during cooking. For leafy greens like spinach and arugula, eating them raw in salads is the simplest way to maximize your intake. If you prefer cooked greens, a light steam or quick sauté is a better choice than a long boil.
Why Vitamin C Matters Alongside Nitrates
When nitrite hits stomach acid, it can form compounds called nitrosamines, which are carcinogenic. This is the reason nitrates in processed meats have raised health concerns for decades. But vegetables come with a built-in safeguard: vitamin C and other antioxidants naturally present in the same foods.
Vitamin C intercepts the chemical reaction that would otherwise produce nitrosamines. It does this by reacting with nitrous acid in the stomach and converting it directly into nitric oxide instead, which then diffuses harmlessly and even benefits blood flow in the gastric tract. This is a key reason why nitrates from vegetables are consistently associated with health benefits while nitrates from cured meats are not. The vitamin C, polyphenols, and other protective compounds in vegetables steer the chemistry in a beneficial direction.
Pairing nitrate-rich vegetables with other vitamin C sources, like bell peppers or citrus in a salad dressing, reinforces this protective effect. But even on their own, most high-nitrate vegetables already contain enough antioxidants to keep the conversion pathway favorable.
Safe Intake Levels
The European Food Safety Authority sets the acceptable daily intake for nitrates at 3.65 mg per kilogram of body weight. For a 70 kg (154 lb) adult, that works out to about 255 mg per day. However, the well-studied DASH diet, which emphasizes fruits and vegetables for blood pressure control, delivers an estimated 174 to 1,222 mg of nitrate daily. That’s up to 550% of the formal guideline for a 60 kg adult.
This gap between the official limit and what healthful diets actually provide reflects the fact that the ADI was set conservatively, largely based on concerns about processed meat and contaminated water rather than whole vegetables. Population studies consistently link high vegetable intake with better cardiovascular outcomes, not worse ones. The presence of protective antioxidants in whole vegetables changes the risk equation entirely compared to isolated nitrate exposure.