What surprised researchers most was where the change appeared to begin — not in the heart, but in the mouth. The study suggests that bacteria living in the mouth may play a major role in how the body processes nitrate-rich foods and supports healthy blood vessels during aging.
For years, beetroot juice has been associated with heart health, but this latest research offers a clearer explanation of why it may help some people more than others. Scientists discovered that the drink altered bacteria inside the mouth in ways that appeared to improve the body’s ability to produce nitric oxide, an important molecule for blood vessel health, as per a report by Science Daily.
The findings were published in Free Radical Biology and Medicine and described as the largest study so far to examine the relationship between dietary nitrate, oral bacteria, nitric oxide biology and blood pressure in both younger and older adults.
Why does the mouth matter for blood pressure?
Nitrate is naturally found in vegetables like beetroot, spinach, arugula, fennel, celery and kale. Before nitrate can help the body, it first interacts with bacteria in the mouth. Certain microbes convert nitrate into compounds that support nitric oxide production.
Nitric oxide helps blood vessels relax and function properly, making it important for blood pressure regulation and overall cardiovascular health.
Researchers found that when the balance of mouth bacteria changes, the nitrate-to-nitric oxide process may work less effectively. In older adults, beetroot juice appeared to improve that balance, as per a report by Science Daily.
What happened during the beetroot juice study?
The trial involved 39 adults under age 30 and 36 adults in their 60s and 70s. Participants completed two separate two-week phases. During one phase, they drank nitrate-rich beetroot juice twice daily. During the other, they consumed a placebo version with the nitrate removed.
Researchers also included a two-week washout period between both phases to reset conditions before testing the next drink.
Using bacterial gene sequencing, scientists examined how the oral microbiome changed after each phase.
Both younger and older adults experienced changes in their mouth bacteria after drinking beetroot juice, but the effects were very different between the groups, as per a report by Science Daily.
Why did older adults respond differently?
Among older participants, researchers noticed a decline in Prevotella, a type of bacteria described as potentially harmful in this setting. At the same time, beneficial bacteria including Neisseria became more common.
The older group also entered the study with higher blood pressure levels than the younger participants. After consuming nitrate-rich beetroot juice, their blood pressure dropped noticeably. That improvement was not seen with the placebo drink and did not occur in younger adults.
Researchers believe the results may be linked to aging and nitric oxide production. As people grow older, the body naturally produces less nitric oxide, which can affect blood vessel function and circulation, as per a report by Science Daily.
Study author Professor Anni Vanhatalo of the University of Exeter said: “We know that a nitrate-rich diet has health benefits, and older people produce less of their own nitric oxide as they age. They also tend to have higher blood pressure, which can be linked to cardiovascular complications like heart attack and stroke. Encouraging older adults to consume more nitrate-rich vegetables could have significant long term health benefits. The good news is that if you don’t like beetroot, there are many nitrate-rich alternatives like spinach, rocket, fennel, celery and kale.”
Researchers also pointed to follow-up studies that further explored the connection between oral bacteria and nitrate processing. A 2025 randomized crossover study involving older adults with treated high blood pressure found that nitrate-rich beetroot juice increased Neisseria while reducing Veillonella in the mouth.
Another 2026 pilot study found that chlorhexidine antiseptic mouthwash disrupted nitrate processing and reduced nitric oxide production, reinforcing the idea that oral bacteria play a major role in cardiovascular health.
Co-author Professor Andy Jones of the University of Exeter said: “This study shows that nitrate-rich foods alter the oral microbiome in a way that could result in less inflammation, as well as a lowering of blood pressure in older people. This paves the way for larger studies to explore the influence of lifestyle factors and biological sex in how people respond to dietary nitrate supplementation.”
Researchers stressed that beetroot juice is not a replacement for medication or standard treatment. Still, the findings suggest that nitrate-rich vegetables could become an important part of healthy aging and blood pressure management.
The study also highlighted a growing idea in nutrition science — that two people can eat the same foods and experience very different health effects because their oral microbiomes process nutrients differently.
FAQs
How long did beetroot juice take to lower blood pressure?
Older adults in the study saw changes after two weeks.
Why is beetroot juice considered helpful for blood pressure?
It contains nitrate, which helps support nitric oxide production in the body.
