The Importance of the Oral Microbiome in Nitric Oxide Production for Better Cognitive and Cardiovascular Health

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Get 20% off Bristle to test your oral microbiome at with the code melanie20
ENDS January 21st!

The Oral Microbiome Health Connection

While the gut microbiome is seemingly all the rage these days, little attention is paid to an equally vibrant and influential microbial community also found within us. Residing on our teeth, gums, tongue, and all throughout the mouth, we also house a collection of bacteria, fungi, and viruses forming the oral microbiome.

The connection between our oral microbiome and oral diseases, such as gum disease and cavities, has been well-established for decades, yet recent research has demonstrated a connection between oral bacteria and overall health. For example, the bacteria Porphyromonas gingivalis can not only cause gum disease, but it also has been associated with the progression of Alzheimer's disease. Or consider the common oral bacteria Fusobacterium nucleatum, which has been connected to inflammatory bowel disease, and a worse prognosis for colorectal cancer.

While most scientific research has focused on “harmful” bacteria and how they can drive diseases in the mouth and body, recent studies also suggest that certain beneficial oral bacteria are vital to promoting and maintaining optimal health. An often overlooked area is the role of the oral microbiome in nitric oxide production. Nitric oxide is critical for improved cardiovascular and cognitive health, and specific microbes in the mouth help produce nitric oxide through the reduction of nitrate. 

I’ve been increasingly interested in the developing research on nitric oxide production in the body, especially with what I’ve learned about NO production from renowned Melanie Avalon Biohacking Podcast guests in the plant-based sphere, such as Simon Hill and Will Bulsiewicz. So I was thrilled when I learned my friends at Bristle have released a new insight on nitrate and nitric oxide, with their oral microbiome test! You can learn more about Bristle and my experience with their test in my previous blog:  Bristle: The Oral Microbiome, Dental Health, Good And Bad Bacteria, Mouth-Body Connection, Tooth Decay, Bad Breath, Proper Oral Hygiene, Testing YOUR Oral Biome, My Bristle Experience, And More!

What Is Nitric Oxide?

Nitric oxide is a gas compound that is critical for multiple biological processes, including cardiovascular health, cognitive health, and immunity (*). It’s a molecule that promotes the widening of blood vessels (also known as vasodilation), which helps regulate and maintain blood pressure. Research has shown that individuals with lower levels of nitric oxide are more likely to have hypertension (*).  

Nitric oxide is also an essential antibacterial molecule that protects against infections. In response to an infection, numerous immune cell types – including macrophages, T-cells, and dendritic cells – produce nitric oxide. At high amounts, nitric oxide can destroy harmful microorganisms.

 In order to achieve optimal health and wellness, we need sufficient levels of nitric oxide in our bodies!

The Oral Microbiome’s Impact On Nitric Oxide Levels

While nitric oxide can be derived from a variety of sources, the oral cavity is a major source of nitric oxide production. Research shows that specific bacteria in the oral cavity can produce nitric oxide, via the enterosalivary nitrate reduction pathway (*). This pathway involves bacteria in the oral microbiome that convert nitrate to nitrite, and then nitrite to nitric oxide (*). Specific nitrate-reducing bacterial species in the oral microbiome, such as Veillonella, Actinomyces, Rothia, and Haemophilus species, are responsible for producing these reduced forms of nitrate. This form of reduced nitrate readily diffuses into circulation, is notably bioavailable, and, importantly, correlates with levels of nitric oxide in the blood.

A healthy oral microbiome with an abundance of nitrate-reducing species is essential for nitric oxide production. Multiple studies have shown this impact, and how the oral microbiome plays an important role in nitric oxide production and, consequently, cardiac health. 

 In 2021, a 96 participant study looked at the oral microbiomes of people with hypertension compared to normotensive individuals. They found that people with hypertension had distinct oral microbiome dysbiosis, with Actinobacteria, Prevotella, and Veillonella species being positively correlated with high blood pressure.

 Another 2021 study with 48 participants demonstrated that normotensive subjects had significantly higher levels of nitric oxide and bacterial concentrations in saliva. Microbiome analysis revealed that normotensive subjects had higher levels of Neisseria species in the oral microbiome.

I find this research fascinating. If you’re interested in diving deeper, check out these studies demonstrating the role of the oral microbiome in nitric oxide production and cardiovascular health:

Analysis of oral microbiota in patients with obstructive sleep apnea-associated hypertension

Definition of hypertension-associated oral pathogens in NHANES 

Oral Microbiome Is Associated With Incident Hypertension Among Postmenopausal Women

Bristle’s Oral Microbiome Nitrate Score

With Bristle’s oral microbiome test, you can now see how your oral microbiome is impacting nitric oxide production, through the new Nitrate score! 

 Specific species found in the oral microbiome are responsible for nitrate reduction, including Haemophilus, Neisseria, Actinomyces, Rothia, and Veillonella species among others. Bristle analyzes these species and uses functional analysis to produce your Nitrate score – the score measures the capacity of a community to convert nitrate to nitric oxide.

 In short, microbes have genes that encode proteins which perform specific functions. The process of nitrate reduction is specifically complex, and requires many different proteins. Bristle measures the specific genes contributing to nitrate reduction, and which are in turn important contributors to cardiovascular and cognitive health. (Note: The image below is not my personal score – I will be retesting soon, and can update with my personal data!)

How To Increase Nitric Oxide?

 Here are a few ways you can increase salivary nitric oxide:

  1. Increase nitrate intake via diet: Modifying your diet to include nitrate-rich foods is a powerful way to increase nitric oxide in the body. Not only does increasing nitrate help improve levels of nitric oxide, it can also significantly improve the oral microbiome broadly (*). Nitrate-rich foods to incorporate into your diet include beet roots and leafy greens such as kale, arugula, and spinach.
  2. Avoid long term use of broad antiseptic mouthwash: Numerous studies have now shown that routine use of broad-spectrum antimicrobial mouthwash can be harmful to nitrate-reducing oral bacteria and is a risk factor for hypertension (****). Steer clear of consistent use of alcohol-based mouthwashes. 
  3. Avoid mouth breathing: Mouth breathing can reduce your salivary flow rate, which is essential to a healthy oral microbiome. People with dry mouth are more susceptible to cavities, gum disease, and reduced levels of nitric oxide. Breathing through the nose significantly increases nitric oxide levels compared to mouth breathing (**).

Final Thoughts

Our oral health is often overlooked when we think about overall health and wellness. Yet more and more research illustrates the critical role a balanced oral microbiome plays in achieving optimal health. Nitric oxide in particular is key for our immunity, cardiovascular health, and cognitive health, and a large portion of this starts with our oral microbiome! 

Bristle’s research team is constantly analyzing their oral microbiome data to uncover new associations between the oral microbiome, and our oral and systemic health. The new nitrate score is one of those developments after months of research and development. All current or past Bristle users now have access to the Nitrate insight in their report, as well as any future insights Bristle develops.

With a simple saliva test from Bristle, you’ll get a complete picture of your oral microbiome, and how it’s impacting your risk for conditions like tooth decay, gum inflammation, bad breath, and gut dysbiosis. You’ll now also learn how your oral microbiome is influencing your nitric oxide levels, which is critical for better heart and cognitive health. Based on your test results, you’ll receive personalized diet, lifestyle, and oral care recommendations, along with one-on-one coaching with one of their oral health experts so you can start optimizing your oral and overall health! I cannot recommend enough taking charge of not only your oral health, but systemic health as well, with the tools provided by Bristle!

Get 20% off Bristle to test your oral microbiome at with the code melanieavalon
ENDS January 21st!


The oral microbiome and nitric oxide homoeostasis

Nitric oxide in hypertension

Nitrate-responsive oral microbiome modulates nitric oxide homeostasis and blood pressure in humans

Isolation and Characterization of Nitrate-Reducing Bacteria as Potential Probiotics for Oral and Systemic Health

Dysbiosis of the Salivary Microbiome is Associated with Hypertension and Correlated with Metabolic Syndrome Biomarkers

Association between hypertension, oral microbiome and salivary nitric oxide: A case-control study

Analysis of oral microbiota in patients with obstructive sleep apnea-associated hypertension

Definition of hypertension-associated oral pathogens in NHANES

Oral Microbiome Is Associated With Incident Hypertension Among Postmenopausal Women

Nitrate as a potential prebiotic for the oral microbiome

Antibacterial mouthwash blunts oral nitrate reduction and increases blood pressure in treated hypertensive men and women

A stepwise reduction in plasma and salivary nitrite with increasing strengths of mouthwash following a dietary nitrate load

Over-the-counter mouthwash use, nitric oxide and hypertension risk

Antiseptic mouthwash inhibits antihypertensive and vascular protective effects of L-arginine

Inhalation of nasally derived nitric oxide modulates pulmonary function in humans

Nasal and oral contribution to inhaled and exhaled nitric oxide: a study in tracheotomized patients

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