Is there a link between the abundance of nitrate-reducing bacteria and arterial hypertension? A systematic review

Context

Nitric oxide is a vasodilator molecule that acts on blood pressure (BP) control, and its production can occur through the reduction of nitrates by oral or intestinal nitrate-reducing bacteria. However, the relationship between nitrate-reducing bacteria and arterial hypertension (HTN) remains under debate.

Objective

Systematically review if there is an association between the abundance of oral and intestinal nitrate-reducing bacteria and the occurrence of HTN in humans.

Databases and eligibility criteria

MEDLINE, Scopus, Cochrane Library, EMBASE, LILACS, Web of Science, Livivo, ProQuest Dissertations, and Google Scholar were searched for eligible articles until February 10th, 2024. Studies were included if they: (1) were observational studies or clinical trials; (2) included adults (≥18 years old) with HTN (systolic BP ≥ 130 mmHg and/or diastolic BP > 80 mmHg and/or use of BP lowering medication); (3) compared (or not) to no-HTN adults; and (4) used next-generation sequencing microbiome analysis to identify bacterial taxa in the oral and/or gut nitrate-reducing bacteria.

Results

The search identified 9365 articles, and 28 were included in the study after applying the inclusion and exclusion criteria; 23 articles assessed the gut microbiota, 4 assessed the oral microbiota, and 1 assessed both. Depletion of nitrate-reducing bacteria was not consistently shown in the studies. The included studies reported reduction, increase, and no change in the nitrate-reducing bacteria genera or species in oral or gut microbiota.

Conclusion

We found no association between the abundance of oral and gut nitrate-reducing bacteria and the occurrence of HTN in humans.

Registration

PROSPERO identification number CRD42022315891.