The Study
The Probiotic Streptococcus salivarius M18 Increases Plasma Nitrite but Does Not Alter Blood Pressure: A Pilot Randomised Controlled Trial
This study gave 10 guys a special probiotic lozenge and found their blood nitrite went up—like a little signal that their body might be making more nitric oxide. But it didn’t make their blood pressure drop, and we don’t know exactly why the nitrite went up. So it’s like seeing a light turn on, but not knowing if it’s because you flipped the switch or the wind blew on it.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Scientists gave men a special probiotic lozenge for two weeks to see if it could increase a molecule called nitrite in their blood, which might help lower blood pressure.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 574 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Even though nitrite went up, it didn't lower blood pressure — meaning more nitrite alone isn't enough to reduce blood pressure in healthy people.
- 2Nitrite in the blood went up from 173 to 223 nM, but saliva and blood pressure didn't change.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Applied Microbiology
Year
2023
Authors
M. Burleigh, B. Rosier, Annabel Simpson, N. Sculthorpe, F. Henriquez, C. Easton
Related Content
Claims (6)
Taking Streptococcus salivarius M18 for 14 days increases plasma nitrite levels but does not lower blood pressure in healthy adult men with normal blood pressure.
Taking Streptococcus salivarius M18 raises plasma nitrite levels, but this change does not correspond to changes in the levels of oral bacteria known to reduce nitrate.
Taking Streptococcus salivarius M18 as a supplement does not change the levels of nitrite, nitrate, or pH in saliva in healthy adult males.
The reason Streptococcus salivarius M18 raises nitrite levels in the blood is not understood, and it is not due to changes in the mouth's bacteria, salivary chemicals, or acidity, nor has the bacteria been shown to produce nitrite directly.
Taking Streptococcus salivarius M18 daily for 14 days raises plasma nitrite levels from 173 nM to 223 nM in healthy adult males, suggesting increased nitric oxide bioavailability, without altering salivary nitrite or the oral microbiome.
The amount of nitrite in saliva cannot be used to determine how much nitric oxide is available in the bloodstream or the level of nitrite circulating in the blood.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.