Increased Nitrate Intake from Beetroot Juice over 4 weeks changes the Composition of the Oral, but not the Intestinal Microbiome Raw sequence reads

Cardiovascular diseases are leading causes of morbidity and mortality, with dietary patterns significantly impacting cardiovascular health. Our study investigated the effects of dietary nitrate from beetroot juice on the oral and intestinal microbiomes of older adults with treated grade 1 hypertension. A randomized, double-blind, placebo-controlled crossover trial was conducted with 15 participants aged 56-71, who consumed nitrate-rich or nitrate-depleted (placebo) beetroot juice for 4 weeks, separated by a 4-week washout period. Results showed significant increases in plasma and salivary nitrate and nitrite levels following the nitrate-rich intervention. The oral microbiome analysis revealed a notable increase in Neisseria and a decrease in Veillonella, with no significant changes in the intestinal microbiome. Our findings suggest that dietary nitrate supplementation may selectively modulate the oral microbiome, enhancing the abundance of nitrate-reducing bacteria, which may contribute to improved cardiovascular outcomes. Further research is needed to explore the long-term implications of these microbiome composition changes on cardiovascular health. Sequencing was performed at the Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna under the project ID JMF-2303-03. Approval for the study was obtained from the Medical University of Vienna's Ethics Committee (ethics number: EK 2238/2018), and the trial was registered on ClinicalTrials.gov (NCT04584372).