An earlier post on this site covered Dr. Nathan Bryan’s research on mouthwash and its effect on oral bacteria, nitric oxide production, and blood pressure. That research does not stop at mouthwash. Dr. Bryan’s work extends to fluoride, both in toothpaste and in fluoridated municipal water, as a separate but related source of oral microbiome disruption with systemic health implications. For anyone who made changes based on the mouthwash research, this context completes the picture.
A Brief Review of the Nitric Oxide Pathway
The oral microbiome contains specific bacteria that convert dietary nitrates, found in leafy greens, beets, and other vegetables, into nitrites, which the body then converts into nitric oxide. Nitric oxide is essential for blood vessel dilation, healthy blood pressure, cardiovascular function, cognitive function, and sexual health in both men and women. Anything that consistently disrupts the oral bacteria responsible for this conversion affects nitric oxide production downstream, with consequences that extend well beyond the mouth.
Fluoride’s Effect on the Oral Microbiome
Fluoride, the active compound in most conventional toothpastes and in fluoridated municipal water supplies, has antibacterial properties that are not selective. While the stated purpose of fluoride in toothpaste is to prevent cavities by inhibiting the bacteria responsible for acid production on tooth enamel, fluoride also inhibits the nitrate-reducing bacteria that produce the nitrite precursors for nitric oxide. Dr. Bryan’s position is that the cumulative effect of daily fluoride exposure, through both toothpaste and water, may meaningfully suppress nitric oxide production in a significant portion of the population.
The Poison Control Warning on Your Toothpaste
The back of any standard fluoride toothpaste tube in the United States carries a specific instruction: if more than the amount used for brushing is swallowed, contact poison control immediately. This label is required by the FDA. Most people have seen it and dismissed it because the quantity used for brushing is small. Dr. Bryan’s concern is not acute toxicity from a single brushing session, it is the cumulative biological effect of daily low-level fluoride exposure over years and decades on a system as sensitive as the oral microbiome.
The 2024 National Toxicology Program Review
In 2024, the National Toxicology Program published a systematic review examining the relationship between fluoride exposure and neuro-developmental outcomes. The review found that higher levels of fluoride exposure were associated with lower IQ scores in children, a finding significant enough to generate regulatory and scientific discussion. The debate around fluoride safety is ongoing and complex, and the NTP review has been interpreted differently by different stakeholders. What it represents is a meaningful shift in the scientific conversation, one that warrants attention from anyone making daily choices about fluoride exposure.
What Dr. Bryan Recommends
Dr. Bryan’s recommendations center on supporting rather than disrupting the oral microbiome. He advises switching to fluoride-free toothpaste options, several of which use hydroxyapatite, a naturally occurring mineral constituent of tooth enamel, as an alternative remineralization agent with a growing evidence base. He also emphasizes the importance of nasal breathing over mouth breathing for preserving the oral microbial environment, and recommends obtaining nitric oxide precursors through dietary nitrates from whole foods rather than relying solely on supplements.
The full interview covers specific product recommendations and the broader context of how daily habits affect the nitric oxide system. Whether or not every recommendation is ultimately adopted, understanding the mechanism gives you the information to make deliberate rather than default choices.
RESOURCE:
Watch the full interview with Dr. Nathan Bryan on The Diary of a CEO with Steven Bartlett:
The Untold Truth About Nitric Oxide & Health | Dr. Nathan Bryan on The Diary of a CEO