Recent research indicates that beetroot juice effectively regulates blood pressure, but oral bacteria play a crucial role in this process. This discovery highlights the body’s intricate biological machinery and the potential of natural remedies in treating hypertension. Scientists at the University of Exeter Medical School in the UK have found that oral bacteria and beetroot juice work together to benefit our health.
High blood pressure, or hypertension, is one of today’s greatest global health challenges, especially among the elderly. It significantly increases the risk of cardiovascular diseases, stroke, and chronic kidney failure. While medication is often essential, scientists are actively searching for simple, low-cost, and less-side-effect-prone natural remedies that can help effectively control blood pressure.
Beetroot Juice and Nitric Oxide: The Mechanism of Blood Pressure Reduction
Study authors Annie Vanhatalo and Andrew Jones determined that the blood pressure-regulating effect of beetroot juice is primarily due to its high dietary nitrate content. Once ingested, nitrate is ultimately converted into nitric oxide (NO). Nitric oxide is a potent vasodilator; it widens blood vessels, improves blood circulation, and lowers blood pressure.
The process involves a complex biological chain:
Nitrate in the Oral Cavity: Approximately 25% of ingested dietary nitrate is absorbed into the bloodstream, from where it concentrates in saliva.
Role of Bacteria: At this stage, anaerobic oral bacteria (specifically Prevotella spp.) become involved. They convert the nitrate in saliva into nitrite, and this bacterial activity is crucial for blood pressure regulation.
Nitrite in Blood – Conversion to Nitric Oxide: Nitrite, in turn, is absorbed into the bloodstream from the gastrointestinal tract. It then converts into nitric oxide, especially in conditions where oxygen concentration in the body is low or the environment is acidic. The resulting nitric oxide causes blood vessel dilation and a reduction in blood pressure.
This study, published in Free Radical Biology and Medicine, aimed to determine how age and the oral microbiome influence both nitric oxide bioavailability and vascular response to dietary nitrate. This was a placebo-controlled, double-blind, crossover intervention trial, which is one of the most reliable forms of scientific research.
Placebo-controlled: The study included a control group that received “fake” beetroot juice with a low nitrate content (placebo).
Double-blind: Neither the participants nor the researchers knew who was in which group.
Crossover intervention: Each participant alternately underwent all experimental conditions, increasing the statistical power of the study.
The study involved 39 young adults (18-30 years old) and 36 older adults (67-79 years old). Participants underwent a 2-week “washout” period, followed by a 2-3 week experimental phase: placebo beetroot juice (PL), nitrate-rich beetroot juice (BRJ), and nitrate-rich beetroot juice + antiseptic mouthwash (BRJ+M). Participants’ blood pressure was regularly measured, vascular function was assessed, and oral microbiome analysis was conducted.
Older Age and Microbiome Impact: Key Findings
The study clearly showed that the blood pressure reduction induced by beetroot juice was less pronounced in older patients (aged 67–79) compared to younger participants. Specifically, after consuming nitrate-rich beetroot juice (BRJ), the reduction in systolic blood pressure in young adults ranged from approximately 5 to 7 mmHg, whereas in older adults, this change was less expressed, averaging within the 3-5 mmHg range.
This phenomenon, with increasing age, is linked to significant changes in the oral microbiome. The study found that with advancing age, the number of bacteria (specifically Prevotella spp.) that play a crucial role in converting dietary nitrate to nitrite decreases. Therefore, to enhance the effect of nitric oxide in older individuals, it may be advisable to regulate the oral microflora, for instance, by taking probiotics.
Importantly, the study also confirmed that the use of antiseptic mouthwashes, which kill these beneficial bacteria, inhibits the conversion of nitrate to nitrite and reduces the blood pressure-lowering effect of beetroot juice. This suggests that conventional oral hygiene methods that are overly aggressive towards the microbiome might negatively impact our body’s ability to benefit from healthy dietary nitrates.
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.
