The Bacteria Behind Good Blood Pressure

In 2013, a team at University College London gave 19 healthy volunteers antiseptic mouthwash and asked them to rinse twice a day for a week. Nobody expected much. Then the results came back: systolic blood pressure had climbed an average of 2.3 mmHg. Salivary nitrite had dropped by roughly 90 percent. Plasma nitrite fell by 25 percent. The volunteers had not changed their diet, their exercise, or their medications. The only thing different was that they had been killing the bacteria on their tongues.

The path from a vegetable to a blood vessel

When you eat leafy greens, beets, or celery, you absorb dietary nitrate through your small intestine. A substantial fraction of that nitrate gets recirculated into saliva — concentrations in saliva can be ten times higher than in blood plasma. Specific species living on the surface of your tongue, particularly those in the Rothia and Neisseria genera, carry an enzyme called nitrate reductase. They reduce that salivary nitrate to nitrite. You swallow, the nitrite hits the acidic environment of your stomach, and some converts to nitric oxide gas. The rest enters your bloodstream, where it serves as a reserve for on-demand nitric oxide production.

Nitric oxide tells the smooth muscle in artery walls to relax. It was so central to cardiovascular science that the three scientists who identified it as a signaling molecule won the Nobel Prize in 1998. What became clear only in the following decade was that the mouth plays a required role in keeping this system running — the enterosalivary cycle described by Lundberg and colleagues in 2004 in Nature Medicine. It is not a side effect of oral biology. It appears to be the design.

Growing back the right bacteria

A 2018 study by Vanhatalo and colleagues addressed whether restoring these bacteria can lower blood pressure. Eighteen volunteers underwent a ten-day nitrate supplementation protocol. The results were striking: Rothia abundance increased by 127 percent. Neisseria increased by 351 percent. Prevotella — a genus that competes with the nitrate-reducing species — fell by 60 percent. The volunteers whose Neisseria and Rothia counts increased the most showed the greatest corresponding increases in plasma nitrite.

The bacteria are not passive bystanders. They are the rate-limiting step. Feed the system nitrate and the right bacteria multiply. More bacteria means more nitrite. More nitrite means more nitric oxide. The blood vessel responds accordingly.

What depletes these bacteria

Antiseptic mouthwash is the most studied disruptor, but not the only one. Antibiotics, a low-vegetable diet, and the general shifts that come with gum disease all reduce populations of nitrate-reducing bacteria. The Vanhatalo data also showed that older adults had lower baseline levels of these species than younger adults — consistent with the well-documented age-related rise in blood pressure that has no single obvious cause.

What Cnvrg measures

The good bacteria score on your oral panel reflects the relative abundance of nitrate-reducing species, including Rothia and Neisseria. When this score is lower than expected for your profile, it indicates reduced capacity to complete the nitrate to nitric oxide conversion that supports healthy blood pressure.

Sources

Kapil V et al. Free Radic Biol Med. 2013. PMID: 23201780. Vanhatalo A et al. Free Radic Biol Med. 2018. PMC6191927. Lundberg JO et al. Nat Rev Microbiol. 2004. DOI: 10.1038/nrmicro929.