Drinking beetroot juice might help older adults lower their blood pressure—and researchers now believe this effect could be thanks to changes in the bacteria inside the mouth.
A new study by scientists at the University of Exeter has shown that the oral microbiome, or the collection of bacteria living in the mouth, plays a key role in how the body processes dietary nitrate, a compound found in many vegetables.
The study, published in the journal Free Radical Biology and Medicine, involved 75 participants: 39 younger adults under the age of 30 and 36 older adults in their 60s and 70s. All participants took part in two trials.
In one, they drank concentrated beetroot juice rich in nitrate twice a day for two weeks. In the other, they drank a similar juice but with the nitrate removed. Each trial was separated by a two-week break.
The researchers found that only the older adults had lower blood pressure after drinking the nitrate-rich beetroot juice. This effect was not seen in the younger group, even though the bacteria in both age groups’ mouths changed after the juice.
In the older adults, certain harmful bacteria, like Prevotella, decreased, while helpful bacteria, such as Neisseria, increased. These changes likely helped the body make more nitric oxide—a molecule that supports blood vessel function and helps regulate blood pressure.
As people age, their bodies naturally make less nitric oxide, and their blood pressure tends to rise. This increases the risk of heart attack, stroke, and other health issues. But a diet high in nitrate-rich vegetables—like beetroot, spinach, celery, rocket, fennel, and kale—can help boost nitric oxide production.
Professor Anni Vanhatalo, one of the lead researchers, explained that the findings highlight the benefits of nitrate-rich foods for older adults. She noted that while beetroot is a good source, many vegetables can provide similar benefits. For people who don’t enjoy beetroot, there are many other options.
The study used advanced gene sequencing to examine the types of bacteria in participants’ mouths before and after each phase of the trial. While the juice changed the microbiome in both young and older adults, only the older group showed improved blood pressure, suggesting that age-related differences in bacteria may play a role.
Professor Andy Jones, another researcher on the project, added that these changes in the oral microbiome could reduce inflammation in the body and support better heart health in older adults. He believes that future studies should explore how lifestyle factors and even gender might affect how people respond to nitrate from food.
Dr. Lee Beniston from the BBSRC, which helped fund the research, said the study is a great example of how science can uncover the connections between diet, microbes, and healthy ageing. Understanding how nitrate affects the body opens new doors for improving heart health through simple dietary changes.
This research shows that for older adults, drinking beetroot juice—or eating other nitrate-rich vegetables—could be a natural and effective way to lower blood pressure by improving the balance of bacteria in the mouth.
If you care about blood pressure, please read studies about unhealthy habits that could increase high blood pressure risk, and eating eggs in a healthy diet may reduce risks of diabetes, high blood pressure.
For more information about blood pressure, please see recent studies that early time-restricted eating could help improve blood pressure, and results showing 12 foods that lower blood pressure.
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