Nitrate-rich foods and nitric oxide: a practical guide

How vegetable nitrate becomes nitric oxide

The body makes nitric oxide in two ways. One uses enzymes and the amino acid L-arginine. The other starts with nitrate from food and does not need those enzymes. The second route runs in steps:

1. You eat vegetables that contain nitrate. It is absorbed into the blood.
2. Your salivary glands concentrate nitrate from the blood and release it into saliva.
3. Bacteria on the back of the tongue convert nitrate into nitrite.
4. Swallowed nitrite is absorbed, and in blood and tissues part of it becomes nitric oxide, especially where oxygen is low.

Because mouth bacteria do step 3, oral hygiene products matter. In a 2013 study in healthy volunteers, a week of antibacterial mouthwash lowered nitrite in saliva and blood and was followed by a small rise in blood pressure. That does not mean you should stop brushing or skip a mouthwash your dentist recommended. It shows how much this pathway depends on the mouth.

Which foods are richest in nitrate

Nitrate content varies a lot with the variety, the soil, the season and how much light the plant received. These groups follow European food-safety assessments and nutrition reviews:

In 2008 the European Food Safety Authority weighed the risks of nitrate in vegetables against the benefits of eating them and concluded that the benefits of vegetables prevail.

What the trials found

• A 2013 meta-analysis pooled trials that used inorganic nitrate or beetroot juice. On average, systolic blood pressure was about 4.4 mmHg lower. The effect on diastolic pressure was smaller and not consistent.
• Most trials were short, from a single dose to a few weeks, and many used concentrated beetroot juice rather than everyday meals.
• Blood pressure responses differ between people. Mouth bacteria, the baseline diet and medications all play a part.

A 2021 review of nitrate-containing foods makes a related point: the effect of nitrate depends on the whole diet. Nitrate in vegetables comes packaged with vitamin C and polyphenols, which is one reason researchers view it differently from the nitrite added to processed meat.

Vegetables are not the same as processed meat

Processed meats such as bacon, ham and some sausages contain nitrite or nitrate added as a preservative. Most of the nitrate people eat, however, comes from vegetables. Health agencies advise limiting processed meat, while vegetables remain a cornerstone of a healthy diet.

Putting it on a plate

• Use arugula or spinach as the base of a salad or wilt them into eggs, soups and pasta.
• Roast beetroot, grate it raw into slaws, or blend cooked beets into hummus.
• Add celery and fennel to soups and stews.
• Boiling leaches some nitrate into the cooking water, so roasting, steaming or eating raw keeps more of it.

Who should be careful

• If you take blood pressure medication, talk to your clinician before adding concentrated beetroot juice or nitrate supplements.
• Beetroot and spinach are high in oxalate. If you have had calcium oxalate kidney stones, ask your clinician how much is right for you.
• Pink or red urine after eating beets (beeturia) is common and usually harmless.

Where this connects to supplements

Supplements marketed for nitric oxide work through different ideas. Some provide arginine or citrulline for the enzyme pathway, some provide nitrate, and some, like noni-based formulas, are built around antioxidant compounds. The noni and nitric oxide guide explains those differences and what the evidence shows.