Nitric oxide supplementation supports heart health and exercise performance

Nitric Oxide Supplements: How Do They Work?

By: Sonali Ruder, DO

Scientifically Reviewed By: Michael A. Smith, MD

Nitric oxide (NO) is a naturally occurring molecule in the body—and it plays many critical roles in various aspects of our health. Its significance spans far and wide, from cardiovascular health to immune function, sexual health, and even cognitive well-being.

Sounds pretty important, right? So, let's talk about ways you can say "yes" to more NO!

We'll unravel the complexities of this important signaling molecule and guide you through supplements that support nitric oxide production in the body—and the numerous health benefits that come from having healthy levels of NO.

What is nitric oxide (NO)?

Nitric oxide, often abbreviated as NO, is a gas that is synthesized within the human body. It acts as an important chemical messenger and is involved in many important physiological processes. It is critical to a variety of cellular pathways, influencing vascular tone in blood vessels, metabolism, neurotransmission, and immune response, to name a few.

Our bodies create nitric oxide from an amino acid called L-arginine, with the help of a specific enzyme called nitric oxide synthase. (You may have seen L-arginine in stores, as it is a popular supplement for athletic performance, although it has other health benefits that benefit non-athletes.)

The discovery of nitric oxide as a signaling molecule revolutionized our understanding of cellular biology and physiology, even earning a Nobel Prize for the pioneering researchers who unraveled its importance. It has even been theorized that nitric oxide, generated by lightning, may have contributed to the origins of life on Earth.

Why is nitric oxide important in the body?

Nitric oxide plays a crucial role in maintaining the body's overall health and function. This versatile molecule is primarily known for promoting cardiovascular health. NO is vital for maintaining the overall health of our blood vessels. By relaxing blood vessels and helping maintain their elasticity, it facilitates healthy blood flow and helps support already-healthy blood pressure.

Nitric oxide is a cornerstone of a healthy endothelium, the functioning layer of cells that lines the inside of blood vessels, including arteries and veins. A healthy endothelium helps maintain vascular tone, allowing for smooth blood flow. An optimally functioning endothelium is an important contributing factor to one's overall heart health.

But the importance of nitric oxide in the body extends well beyond heart health. It's an integral molecule in maintaining our overall well-being and contributes to numerous essential physiological functions. NO supports the immune system, helps maintain healthy sexual function in men, and encourages healthy brain function.

Best nitric oxide supplements

You can boost your nitric oxide levels by eating certain foods that are high in dietary nitrates. Our bodies can convert these nitrates to nitric oxide. Good food sources of dietary nitrates include leafy and root vegetables, especially spinach, cabbage, lettuce, chard, and beets. Be aware: the nitrate content of produce varies with the season and soil conditions.

A more reliable way to ensure optimal NO levels is through supplementation. To be clear, nitric oxide supplements don't contain actual nitric oxide gas! (That would pretty much defy physics.) Instead, these supplements contain substances that support nitric oxide production, including the amino acid L-arginine and NO-promoting polyphenols—healthy compounds found in many plants and in plant-based foods. Other potential sources are food-derived nitrates from beets and the amino acid L-citrulline.

Here’s a rundown of the best nitric oxide supplements:


L-arginine supplements are the most basic type of nitric oxide supplement. They contain the amino acid L-arginine, which is a precursor to nitric oxide and can be converted to NO in the body. L-arginine supplements encourage healthy levels of endothelial NO production, promoting blood flow and circulatory health. They also provide other health benefits, such as maintaining healthy tissue and bones, promoting healthy sexual function and exercise performance, and supporting a healthy immune system.

However, regular L-arginine only stays in your blood for a short amount of time. So, there are high-quality supplementation formulas designed to support blood L-arginine levels for a longer time. Because these supplements stay in your blood longer, they provide additional vascular support.

Some supplements may combine arginine with other ingredients, like ornithine (another amino acid), for additional benefits relating to athletic performance. These formulations combine protein-building amino acids to promote muscle health and recovery post-exercise.

Another amino acid that is often mentioned when talking about NO supplements is L-citrulline. That's because L-citrulline is a precursor to L-arginine (just as L-arginine is a direct precursor to nitric oxide). However, since L-citrulline needs to be converted to L-arginine, many prefer to skip the middleman and take L-arginine to support the production of NO.


Polyphenols are a class of chemical compounds that occur naturally in plants and are available in standardized doses in supplement form. Many polyphenols have antioxidant properties, protecting our cells from free radicals. Polyphenols can also encourage NO levels, supporting endothelial function and cardiovascular health.

Some examples of polyphenol sources that can support NO are aronia berry, pomegranate, and Pycnogenol®, an extract of French maritime pine bark.

  • Aronia berry. Aronia berries, also known as black chokeberries, are small, edible pea-sized berries that grow on shrubs native to North America. Chokeberry extract is a rich source of polyphenols and is included in some NO supplements. These polyphenols can promote the activity of endothelial NO synthase, the enzyme responsible for producing nitric oxide in the body. In a 12-week randomized controlled clinical trial, daily aronia extract was found to encourage healthy vasodilation and blood flow compared with placebo.
  • Pycnogenol. Pycnogenol is an extract that comes from the bark of the French maritime pine tree and is available in supplement form. It has been shown to promote a healthy functioning endothelium and arterial blood flow. Pycnogenol also provides powerful protection against oxidative stress and helps promote a healthy inflammatory response. Through these actions, pycnogenol supports healthy blood flow throughout the body.
  • Pomegranate. Pomegranate is a nutrient-dense fruit with many unique compounds that are beneficial for our health. One of its most impressive benefits is its support for blood vessel health. It supports healthy cardiovascular endothelial function.


Flavonoids are a subclass of polyphenolic compounds found in a variety of supplements and occur naturally in various plants and plant-based foods and beverages. Like other polyphenols, they support nitric oxide levels by enhancing its production.

Some examples of flavonoid supplements are Kaempferia parviflora extract, quercetin and hesperidin.

  • Kaempferia parviflora extract, also known as Thai black ginger, is native to Southeast Asia and has been studied for male sexual health support for years. It works by promoting NO synthesis. This helps maintain healthy blood vessels and promotes healthy blood flow, which is vital to a healthy male sexual response.
  • Quercetin is a flavonoid found in many plants and foods, such as onions, black tea, red wine, apples, and berries. It supports a healthy inflammatory response and offers antioxidant protection. If taking a quercetin supplement, choose a formula that is bioavailable.
  • Hesperidin is a compound derived from citrus peels that helps maintain blood vessel and circulatory health by boosting endothelial production of NO. In a randomized controlled trial, 500 mg of sweet orange peel extract encouraged flow-mediated dilation, an indicator of healthy endothelial function. It also promoted a healthy inflammatory response.

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What are the benefits of nitric oxide supplements?

High-quality nitric oxide supplements offer a wide range of potential health benefits, including:

  • Healthy blood flow:

    NO supplements are intended to help promote healthy circulation and oxygen delivery to your tissues and muscles.
  • Cardiovascular support:

    By maintaining healthy blood pressure and supporting endothelial function and arterial health, nitric oxide supplements can contribute to overall cardiovascular health.
  • Healthy sexual function:

    NO plays a role in sexual health, and some nitric oxide supplements may support healthy sexual  function.
  • Cell signaling:

    NO is a critical cellular messenger, acting almost like little telegrams, relaying information to different tissues and cells throughout the body.

What is the best time to take nitric oxide supplements?

Nitric oxide supplements can be taken at any time. Look for stimulant-free nitric oxide supplements that won't cause any adverse effects if taken in the evening.

L-arginine is an amino acid. When it comes to amino acid supplements, their absorption can be affected by the foods with which they're taken, and by other amino acids. Some amino acids can compete with the absorption or action of other amino acids, while others may enhance their effects.

The labels on some amino acid supplements suggest taking them on an empty stomach to minimize potential competition and ensure absorption. However, this may not be the most practical approach in all cases. When in doubt, it's best to follow the instructions on the supplement label for optimal results or speak with a health care provider.

Should I take nitric oxide every day?

The concept of "taking nitric oxide" is somewhat of a misnomer. Instead, you're either taking a nitric oxide precursor, such as arginine, or compounds that stimulate nitric oxide production and promote endothelial function, like plant polyphenols. For optimal benefits, take nitric oxide supplementation daily, since your body relies on NO constantly and extensively.

As with other dietary supplements, the amount of nitric oxide supplements you take will be dependent on your health goals and the product label. Before making any lifestyle change, be it an exercise program or a nutritional supplement, talk with a health care provider.

Wondering what nutrients can help you maintain healthy blood pressure? Our health needs quiz can give you a personal recommendation!

About the Author: Sonali Ruder, DO, is a board-certified emergency medicine doctor, classically trained chef, cookbook author and founder of the popular website, Dr. Ruder is a contributing writer, recipe developer, spokesperson, and health and wellness expert for several national magazines, websites, and organizations. Her passion is giving people the tools to take control of their health, starting in the kitchen!