In this prospective and longitudinal analysis, over half of the women without hypertension at the beginning developed it by the end of the study period. Fifteen bacterial species present at baseline were significantly associated with the risk of developing hypertension; 10 species were associated with a 10-16% increase in risk (e.g., Streptococcus anginosus, Streptococcus salivarius, etc.), and 5 were associated with a 9-18% reduction in risk, (including Neisseria subflava, Aggregatibacter segnis, etc.), and these associations remained even after fully adjusted analysis (in 13/15 species).
This study appears to be the first prospective analysis linking specific bacterial species to the development of hypertension. Although mechanisms were not included in this analysis, one possibility suggested by the authors is that the presence of species which possess nitrate-reducing capacities may increase the available nitric oxide (NO) levels, leading to a reduction in blood pressure. They note that mammalian cells lack this ability, and thus we are dependent on microbial action to provide NO through this pathway. Other distinct mechanisms likely also play a role, such as a direct acceleration of atherosclerosis by certain species. This study supports the growing awareness of the relationship between the microbiome and blood pressure regulation, raising the hope that modulation of the oral microbiome may help prevent incident hypertension.