Nitric oxide is a naturally occurring molecule that plays an important role in circulation, blood pressure, exercise performance, and several other functions in the body. One of its best-known roles is vasodilation, helping the muscles surrounding blood vessels relax so that blood vessels can widen and blood can flow more easily.

Because of this, nitric oxide has attracted considerable interest in sports nutrition and men's health, with a growing number of supplements marketed as “nitric oxide boosters.”

But there is an important distinction: nitric oxide supplements generally do not contain nitric oxide itself. Instead, they contain ingredients such as dietary nitrates, L-arginine, or L-citrulline that the body can use to produce nitric oxide.

So, can you increase nitric oxide naturally? And do supplements actually work?

Here is what the science says.

What Is Nitric Oxide?

Nitric oxide (NO) is a signaling molecule produced naturally by the body. It has several roles, but one of its most important is regulating the function of blood vessels.

When nitric oxide signals the smooth muscles in blood vessel walls to relax, the vessels widen. This process, known as vasodilation, can improve blood flow and help deliver oxygen and nutrients to tissues throughout the body.

Nitric oxide is produced through more than one pathway. One involves the amino acid L-arginine, which is converted into nitric oxide by enzymes called nitric oxide synthases. Another pathway begins with dietary nitrate, which can be converted into nitrite and eventually nitric oxide.

This is why both nitrate-rich foods and certain amino acids, particularly L-arginine and L-citrulline, are often discussed when it comes to supporting nitric oxide production.

Why Does Nitric Oxide Matter?

Because nitric oxide influences blood vessel function, it has implications for several areas of health.

Blood flow and cardiovascular health: By promoting vasodilation, nitric oxide helps regulate blood flow and blood pressure. Research suggests that dietary nitrate, particularly from vegetables and beetroot, may have beneficial effects on blood pressure in certain populations.

Exercise and physical performance: During exercise, working muscles require more oxygen and nutrients. Nitric oxide-related vasodilation can help increase blood flow to active muscles.

Sexual function: Nitric oxide also plays a role in erectile function. It helps relax smooth muscle in the penis, allowing blood to flow into the erectile tissue.

How to Increase Nitric Oxide Naturally

1. Eat More Nitrate-Rich Vegetables

One of the simplest ways to support nitric oxide production is to include more nitrate-rich vegetables in your diet.

Good sources include:

• Beetroot

• Spinach

• Arugula

• Lettuce

• Celery

• Watercress and other leafy greens

Dietary nitrate can enter the body's nitrate-nitrite-nitric oxide pathway, eventually contributing to nitric oxide production. This pathway is partly dependent on bacteria in the mouth that help convert nitrate into nitrite.

2. Include Foods Rich in Antioxidants

Nitric oxide is a relatively unstable molecule and can be broken down by free radicals. Antioxidants may help reduce oxidative stress and support nitric oxide availability.

Foods naturally rich in antioxidants include:

• Fruits and vegetables

• Nuts and seeds

• Whole grains

• Berries

• Citrus fruits

• Other plant foods rich in polyphenols

Some of the antioxidants commonly discussed in relation to nitric oxide include vitamin C, vitamin E, and polyphenols. Interestingly, many nitrate-rich vegetables also contain antioxidants, which may be one reason a diet rich in vegetables can support nitric oxide biology through multiple pathways.

3. Exercise Regularly

Exercise is another natural way to support nitric oxide production.

The inner lining of your blood vessels, known as the endothelium, produces nitric oxide. 

Regular exercise has been shown to improve endothelial function and vasodilation in both healthy people and people with certain cardiovascular risk factors. A combination of aerobic activity such as walking, jogging, cycling, or swimming and resistance training can be a practical approach to maintaining cardiovascular and vascular health.

You do not necessarily need intense workouts. Consistency matters more than choosing one particular form of exercise.

4. Pay Attention to Your Oral Health

Certain bacteria in the mouth help convert dietary nitrate into nitrite, an important step in the nitrate-nitrite-nitric oxide pathway. Some studies have found that antiseptic mouthwash can reduce these bacteria and temporarily interfere with nitrate conversion.

This does not mean you should stop taking care of your oral health or avoid mouthwash altogether. Oral hygiene remains important.

Rather, it highlights an interesting point: the bacteria living in your mouth can play a role in how your body processes dietary nitrate.

If you use an antiseptic mouthwash regularly, especially for a specific dental condition, speak with your dentist about whether it is appropriate for you.

5. Get Enough L-Arginine Through Your Diet

L-arginine is an amino acid that the body can use to produce nitric oxide.

It is naturally found in protein-rich foods, including:

• Nuts and seeds

• Legumes

• Meat

• Fish

• Dairy products

• Other protein-containing foods

The body can normally produce L-arginine on its own, so most healthy people do not necessarily need supplemental L-arginine simply to maintain nitric oxide production.

Do Nitric Oxide Supplements Work?

Products marketed as nitric oxide boosters typically contain compounds that the body can use to produce nitric oxide rather than nitric oxide itself. Common ingredients include:

• L-arginine

• L-citrulline

• Dietary nitrate, often from beetroot

• Citrulline malate

L-Arginine

L-arginine is directly involved in the body's nitric oxide production pathway.

Some research suggests that L-arginine supplementation can improve blood flow or reduce blood pressure in certain populations. It has also been studied for erectile dysfunction.

However, evidence for improving exercise performance in healthy people is inconsistent. A review from the National Institutes of Health notes that studies using supplemental L-arginine have generally found little to no improvement in athletic performance.

L-arginine can also cause gastrointestinal side effects, particularly at higher doses.

L-Citrulline

L-citrulline takes a slightly different route.

The body can convert L-citrulline into L-arginine, which can then be used in nitric oxide production. Because of the way it is processed, supplementing with L-citrulline can raise blood L-arginine levels more effectively than taking L-arginine alone in some circumstances.

Some studies suggest potential benefits for blood flow, exercise performance, or muscle soreness, but results are mixed. Research also varies considerably in terms of dosage, exercise type, and whether citrulline is combined with other ingredients.

Beetroot and Dietary Nitrate

Beetroot is one of the richest dietary sources of nitrate and has been extensively studied for its potential effects on nitric oxide-related pathways.

Research suggests that nitrate supplementation may improve certain aspects of exercise performance, including endurance and time to exhaustion, particularly in some recreationally active or less-trained individuals. However, the benefits are generally modest, and highly trained athletes may not experience the same effects.

This makes beetroot an interesting example of why “natural” does not automatically mean “guaranteed to work.”

Are Nitric Oxide Supplements Safe?

For healthy adults, ingredients used to support nitric oxide production are generally considered safe when used appropriately. But supplements are not risk-free.

Potential concerns include:

• Low blood pressure: Ingredients that increase nitric oxide or promote vasodilation may lower blood pressure further in people who already have hypotension.

• Digestive symptoms: L-arginine can cause nausea, diarrhea, or other gastrointestinal discomfort, particularly at higher doses.

• Medication interactions: Nitric oxide-related supplements can interact with certain medications, particularly those that affect blood pressure or blood vessel dilation.

• Beetroot supplementation: Beetroot can temporarily turn urine or stools reddish, which is generally harmless but can be surprising if you are not expecting it.

If you take prescription medication, have a medical condition, have low blood pressure, or are considering high-dose supplementation, it is best to speak with a doctor or qualified healthcare professional first.

So, What Is the Best Way to Increase Nitric Oxide?

There is no single food, supplement, or “nitric oxide booster” that works for everyone.

Instead, the evidence points toward a broader approach:

Eat more nitrate-rich vegetables. Eat a varied, plant-rich diet. Exercise regularly. Look after your oral health. Consider supplements selectively.