A new study shows that beetroot juice can reduce blood pressure in older adults by enhancing nitric oxide pathways through shifts in oral bacteria, pointing to a simple nutritional strategy for healthier aging.
Study: Ageing modifies the oral microbiome, nitric oxide bioavailability and vascular responses to dietary nitrate supplementation. Image Credit: Liudmyla Chuhunova / Shutterstock
In a recent study published in the journal Free Radical Biology and Medicine, researchers investigated whether nitric oxide (NO) deficiencies, a common aspect of human aging, could be mitigated by consuming nitrate-rich beetroot juice. The study leveraged data from a randomized crossover trial comparing the impacts of beetroot juice consumption on young and older adults.
Study findings revealed that beetroot juice consumption substantially lowered blood pressure (BP) scores in older adults, while having no statistically significant impact on their younger counterparts. Furthermore, the study found that this BP improvement was associated with higher plasma nitrite levels and correlated with decreases in a Prevotella-dominated bacterial module, rather than directly with increases in nitrate-reducing genera. The Prevotella-dominated group included taxa capable of dissimilatory nitrate reduction to ammonia (DNRA), which may divert nitrite away from NO production. These findings support the notion that dietary nitrate may enhance blood pressure regulation in older adults, with microbiome shifts potentially mediating this effect. However, endothelial function and arterial stiffness were unchanged.
Background
Decades of research have elucidated some of the routine processes associated with aging, with the body's deteriorating ability to produce nitric oxide (NO), a key molecule for cardiovascular health, well-documented. Conventional interventions often involve the use of pharmacological supplements; however, a significant number of patients respond poorly to these interventions, prompting the search for newer, naturally derived, and physiologically safe alternatives.
Recent research has also established robust links between oral health and systemic disease. However, the biological mechanisms governing these benefits remain largely unknown. One of the few well-documented pathways involves the conversion of dietary nitrate, abundant in green leafy vegetables and beetroot, into nitric oxide (NO). Studies have shown that this process entirely depends on specific oral bacteria (living on human tongues) that process the machinery to convert (enzymatically reduce) nitrate to nitrite. This nitrite is then converted to NO, a vital signaling molecule that relaxes blood vessels and lowers blood pressure.
Unfortunately, aging substantially hinders this process, as the body's primary mechanism for producing NO, via the enzyme nitric oxide synthase (NOS), becomes less efficient. This age-related decline has been observed to contribute to hypertension and increased cardiovascular risk. However, the oral microbiome and vascular system responses to the aging process remain unknown. Elucidating these interactions may allow for a new "backup" means to mitigate NO deficiency, thereby contributing to healthier aging. In this study cohort, however, baseline NO biomarkers were similar across age groups, suggesting that NO availability may be maintained during healthy aging, and thus, age-related NO decline should be framed cautiously.
About the study
The present study aimed to address the knowledge gaps by conducting a placebo-controlled, double-masked crossover trial involving 39 young adults (aged 18–30) and 36 older adults (aged 67–79), to investigate the impacts of different oral solutions (beetroot juice and mouthwash) on participants' oral microbiome and vascular responses.
Individuals with known medical histories of pulmonary, metabolic, or cardiovascular diseases were excluded from the sample cohort. Exclusion criteria also included oral diseases, smoking, high BP (> 140/90 mmHg) at baseline, and recent (<3 months) antibiotic use.
The study intervention lasted two weeks (each treatment), separated by additional two-week 'washout' periods. The interventions included:
- Nitrate-rich beetroot juice (BR): 2 × 70 ml shots/day, each containing ~595 mg nitrate.
- Placebo beetroot juice (PL): An identical juice with the nitrate removed. This served as the experimental control.
- Antiseptic mouthwash (MW): To observe the impacts of externally disrupting oral bacteria.
Data collection involved the collection of tongue swabs (before and after each period) for oral microbiome analysis via high-throughput 16S rRNA gene sequencing. Additionally, participants' key cardiovascular health markers (brachial and central BP) and endothelial function (using flow-mediated dilation [FMD]) were recorded at the same frequency. Finally, Plasma nitrate and nitrite levels were measured as proxy biomarkers of NO bioavailability.
Study findings
The study demonstrated a surprising contrast in how young and older participants responded to the dietary nitrate. The latter cohort had higher baseline BP (mean arterial pressure of 95 vs. 87 mmHg, P < 0.001), but when provided the nitrate-rich beetroot juice, demonstrated a significant reduction in brachial mean arterial pressure (4 ± 4 mmHg [P = 0.003]). Young, healthy adults, however, did not see any such change. Post-nitrate BP was lower than after mouthwash, but not lower than after placebo beetroot juice, which itself increased plasma nitrate and nitrite and had a modest effect on BP in older adults.
Further analyses revealed that the nitrate intervention directly correlated with the decrease in a co-occurring module of bacteria dominated by the genus Prevotella. Prevotella concentrations, in turn, were strongly associated with both the increase in plasma nitrite (r = -0.72, P = 0.001) and decreased BP.
The use of antiseptic mouthwash was also associated with reduced oral microbial diversity (Shannon index, P = 0.004) and impaired vascular function in the young group. Conversely, nitrate supplementation altered the oral microbiome in older adults, leading to increases in specific nitrate-reducing genera, including Neisseria and Rothia. Notably, Neisseria exhibited a proportionally greater increase in older adults compared to the young group.
Conclusions
The present study reveals that dietary nitrate may serve as a potent tool for enhancing cardiovascular health, particularly in older adults. The findings demonstrate, for the first time, that a shift in the oral microbiome associated with higher plasma nitrite levels may contribute to the blood-pressure-lowering effect of nitrate, rather than proving direct causation. This research opens a new frontier for targeted nutritional and probiotic strategies to support cardiovascular health, especially in our aging global population.
Journal reference:
- Vanhatalo, A., L’Heureux, J. E., Black, M. I., Blackwell, J. R., Aizawa, K., Thompson, C., Williams, D. W., van der Giezen, M., Winyard, P. G., & Jones, A. M. (2025). Ageing modifies the oral microbiome, nitric oxide bioavailability and vascular responses to dietary nitrate supplementation. Free Radical Biology and Medicine, 238, 682–696. DOI – 10.1016/j.freeradbiomed.2025.07.002, https://www.sciencedirect.com/science/article/pii/S0891584925008068