No Effect Of Acute Nitrate Ingestion On The Oral Microbiome In Healthy Sedentary Young Women

Dietary nitrate (NO3-) supplementation can elicit beneficial physiological effects associated with increased nitric oxide bioavailability via the oral microbiome. However, both the effects of NO3- in women, and the influence of NO3- on oral microbial composition are understudied. PURPOSE: To examine if acute NO3- ingestion rapidly modulates oral microbial composition in healthy sedentary young women. METHODS: In a double-blinded randomized crossover design, twenty healthy young women participated in two conditions, during the early follicular phase, to consume a moderate dose of NO3--rich beetroot juice (BR; ~12 mmol of NO3- total) and NO3--depleted beetroot juice (PL). A resting venous blood draw and a buccal sample from the cheek were obtained ~2.5 hours after supplementation. Nitric oxide bioavailability was measured via surrogate markers, plasma [NO3-] and [nitrite (NO2-)], using gas phase chemiluminescence. Buccal cell sample DNA was amplified using polymerase chain reaction (PCR) targeting the V3 - V4 region of the 16S rRNA gene. Following index PCR, amplicons were pooled and sequenced using the iSeq Illumina NGS sequencer. Subsequent reads were clustered into amplicon sequence variants and analyzed for alpha and beta diversity and relative abundance. RESULTS: Plasma [NO3-] (PL: 47 ± 16 μM vs. BR: 615 ± 135 μM, P < 0.001) and plasma [NO2-] (PL: 260 ± 252 nM vs. BR: 609 ± 326 nM, P < 0.001) were increased after an acute NO3- dose. BR did not significantly impact alpha diversity (i.e., species richness or evenness), beta diversity (i.e., global bacterial populations) or the relative abundance of the phylum and genus (P > 0.05). CONCLUSIONS: A moderate acute NO3- dose does not influence the oral microbiome but significantly increased markers of nitric oxide bioavailability in young women. Future studies are required to understand the impact of NO3- supplementation strategy on oral microbial composition. Internal funding from Pepperdine University