Nitric Oxide: What Is It? Why Is It Important?

Nitric Oxide: What Is It? Why Is It Important?

"My hope is that people will not only be able to improve their current health conditions, but prevent disease and premature aging in the first place."

—Dr. Bryan, Functional Nitric Oxide Nutrition

What is Nitric Oxide (NO)?

Nitric Oxide is a gas produced in the body that is one atom of nitrogen (N) and one atom of oxygen (O) that acts as a signaling molecule between cells. In fact, nitric oxide is so crucial to the proper function of the body that the Nobel Prize in Physiology or Medicine in 1998 was given jointly to Robert F. Furchgott, Louis J. Ignarro and Ferid Murad "for their discoveries concerning nitric oxide as a signaling molecule in the cardiovascular system." While nitric oxide benefits nearly all body systems including immunology, gastroenterology, endocrinology, and musculoskeletal, we will focus on how it contributes greatly to the health of the cardiovascular system.

What does Nitric Oxide do?

Nitric oxide has a slew of functions within the body, but its primary function is that of regulating the cardiovascular system. The gas works on the endothelial layer of the vessels causing them to relax, thus widening the vessels and allowing more blood to pass through. This is vasodilation, which increases blood flow and decreases blood pressure. Hypertension, or elevated blood pressure, is the number one risk factor for cardiovascular disease. Approximately two thirds of Americans have hypertension, which means that nearly one million people are at higher risk for cardiovascular disease. Due to its natural ability to reduce blood pressure, nitric oxide can help people get off their blood pressure medications.

Because of the vasodilation and resulting increased blood flow circulating throughout the vessels, more oxygen is able to get to the cells of the body. Nitric oxide is crucial for healthy blood and oxygen circulation.

While managing blood flow throughout the cardiovascular system is considered nitric oxide’s primary role, this life sustaining gas has numerous peripheral roles as well.

  • Topical uses: Nitric oxide regenerates the tiny blood vessels in the skin, restoring its elasticity. It can be used in skin care as an anti-aging serum, because of these re-tightening properties. It also assists in reducing acne prevalence, lightens scars, and aids in the healing process. It can be used on cuts or scrapes to help the skin heal itself faster.
  • Immune system: Once immune cells recognize molecular patterns of pathogens, activated macrophages inhibit pathogen replication by releasing a variety of effector molecules, including nitric oxide. Nitric oxide regulates the functional activity, growth, and death of many immune cell types.
  • Stem cells: Nitric oxide works with mesenchymal stem cells and macrophages to make the stem cell environment more conducive for stem cell repair. Studies show that nitric oxide contributes to proliferation and differentiation of stem cells as it interacts with intercellular compounds and structures.
  • Inflammation Response: In an inflamed joint, nitric oxide regulates the synthesis and functions of several inflammatory cells, acting as a powerful anti-inflammatory. It can also mediate the effects of proinflammatory cells, meaning the powerful gas has both anti-inflammatory and proinflammatory properties, depending upon the needed response.
  • Additional Functions: Nitric oxide is also used in the respiratory tract, central and peripheral nervous systems, and the gastrointestinal-urogenital tract, as well as in cell proliferation.

How Does the Body Produce Nitric Oxide?

There are two main processes by which the body can produce nitric oxide. The first is within the endothelial cells, or the cells that form the inner lining of the blood vessels. These cells generate nitric oxide and release it directly into the bloodstream through the eNOS (endothelial nitric oxide synthase) system. Young healthy people naturally produce adequate levels of nitric oxide in their bodies, but as we age, we have difficulty producing it, and thus require help to maintain appropriate levels. Most people over the age of 40 are found to be nitric oxide deficient due to the decline of endothelial function. Because of the prevalence of nitric oxide deficiency, nearly everyone over 40 should take a supplement in order to maintain suitable levels of nitric oxide.

As we age, we lose 85% of our ability to make Nitric Oxide.

The second way our bodies make nitric oxide is with our saliva. When salads or other leafy green vegetables are broken down and digested in our stomach and intestines, nitrate from the food is taken up and recirculated through the salivary glands. As we chew and swallow, the nitrate interacts with certain types of healthy bacteria found at the back of our tongue. So every time we salivate, chew, and swallow, the nitrate is broken down into nitrite and nitric oxide. This saliva-produced nitric oxide helps kill foodborne pathogens such as e. coli, listeria, and clostridium botulinum, as well as helicobacter pylon (the bacteria responsible for gastric ulcers). Because nitrate is needed to be broken into nitrite and nitric oxide, it is important that we get plenty of leafy green vegetables in our diets. 

What Causes Nitric Oxide Deficiencies?

Since endothelial function naturally decreases over our lifetime, it’s crucial that we don’t inadvertently deprive our bodies of any nitric oxide we can get. One of the most common ways people unknowingly decrease their nitric oxide supply is by not eating enough vegetables, especially leafy green vegetables in their diets. Leafy greens have a high concentration of nitrate so incorporating them into our regular diets can work wonders for our nitric oxide levels. 

Another common mistake is regularly using antiseptic mouthwash. Clinical studies have found that antiseptic mouthwash kills the healthy bacteria at the back of the tongue which means the nitrate metabolized from food cannot be converted into nitric oxide. 

Another big problem that leads to nitric oxide deficiency is when the stomach pH is off balance. If the stomach acidity is not in the healthy range (about 1.5 to 3.5), it will not be able to break nitrate down into nitrite and nitric oxide. This interrupts the saliva production of the nitric oxide cycle as well. People who take antacids or medication for acid reflux solve one problem, but create another and should work toward getting off their antacid medication. But if stomach acid is at a correct level, the process can function appropriately, and nitric oxide is created every time we swallow.

What are Good Sources of Nitric Oxide?

We can get an incredible amount of nitric oxide from our diet and therefore should not have to rely on supplements. Some of the highest levels of nitrate can be found in beetroot juice, leafy green vegetables, garlic, cured meats, dark chocolate, citrus fruits, pomegranate, nuts and seeds, watermelon, and red wine. 

However, because of decreased endothelial function the older we get, as well as other contributing factors that limit the body’s potential from maximizing its nitrate intake, people over the age of 40 should consider taking a nitric oxide supplement to ensure the body gets the amount it needs for proper function.

What Happens if you Don’t Get Enough Nitric Oxide?

Nitrate is a compound that the body is unable to use since we do not have the enzyme necessary to utilize it. It has been found that people who cannot break down nitrate into nitrite and nitric oxide are at higher risk of cardiovascular disease. This inability to break down nitrate can come from either a lack of healthy bacteria in the mouth or a stomach pH that is off balance. 

Deficiencies of nitric oxide can cause hypertension, atherosclerosis, coronary heart disease, obstructive and vasospastic diabetes mellitus, dyslipidemia, and stroke. Many of these conditions arise from a buildup of plaque in the arteries, which nitric oxide helps reduce.

What are Symptoms of Nitric Oxide Toxicity?

The primary symptom of having an over-abundance of nitric oxide is low blood pressure. Because nitric oxide causes vasodilation and therefore increases blood flow, having low blood pressure is a sign that too much nitric oxide is working on the blood vessels. 

Nitric oxide toxicity can also result in nausea, fatigue and dizziness, as well as symptoms related to pulmonary response including shortness of breath and burning in the throat or chest. However, these symptoms can be delayed several hours.

One study in the 1970s found that elevated levels of nitric oxide leads to cancer in the body; however, this study has since been proven wrong. Reports of nitric oxide causing cancer are erroneous. The greatest risk it provides is methemoglobinemia, or nitrites causing the oxidation of hemoglobin, resulting in the blood becoming incapable of carrying oxygen throughout the bloodstream. This condition only exists when exposed to 150 times the amount of nitric oxide used for therapy. So the average person consuming a standard amount of nitrates, comes nowhere near the risk of consuming enough to cause methemoglobinemia [Dr. Bryan]. 

Ultimately, the main concerns for nitric oxide toxicity are low blood pressure, dizziness, shortness of breath, and so on. And if an individual does experience these symptoms, he or she should cut back on nitrate consumption and the conditions should resolve.


So what does it all mean? Nitric oxide has incredible health benefits. It can literally save lives and prevent disease if we can get enough of it into our system. Americans are generally nitric oxide deficient, and the amount we get in an average diet is far below the levels needed to cause any toxic harm, so there is always room to improve.

Nitrate from our diet is broken down into nitrite and nitric oxide, but the environment in the body must be just right to allow this process to occur. We need the healthy bacteria at the back of our tongue as well as an appropriate stomach pH level to allow for the breakdown of nitrate. People in their 20s generally have no problem producing nitrate, but natural production tends to decrease the older we get. So individuals who are 40 years or older should enhance their diets with nitric oxide supplements, or at least be sure to include nitrate-rich foods to ensure they are consuming appropriate levels. As we maintain sufficient levels of nitric oxide in our bodies, we have better vasodilation, blood flow, and cellular function. 


Bryan, Nathan S. “But I Thought Nitrite and Nitrate Were Toxic.” Functional Nitric Oxide Nutrition, Crescendo Publishing, 2018, pp. 63–68.

It’s your body. It’s your life. Ingredients matter.


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Dr. Bryan shares the importance of Nitric Oxide (NO). It clearly illustrates that diet and lifestyle modifications can significantly improve NO production and arms the reader with information so they can immediately implement what they have learned.

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