A new study suggests that one of the keys to healthy blood pressure in older adults may actually begin inside the mouth.
Researchers from the University of Exeter found that drinking nitrate-rich beetroot juice twice a day for two weeks lowered blood pressure in older adults while also changing the balance of bacteria living in their mouths.
The study, published in Free Radical Biology and Medicine, is one of the largest investigations so far exploring how dietary nitrate affects oral bacteria, nitric oxide production, and blood vessel health in younger and older adults.
Scientists say the findings reveal an unexpected connection between nutrition, aging, and the mouth microbiome.
The mouth contains billions of bacteria. Some are harmful, but many help support normal health. Researchers now believe certain mouth bacteria are essential for turning nitrate from vegetables into nitric oxide, a molecule that helps blood vessels relax and maintain healthy circulation.
Nitric oxide is especially important because it supports blood vessel flexibility and healthy blood flow. Lower nitric oxide levels have been linked to hypertension, heart disease, and aging-related vascular problems.
As people get older, the body naturally produces less nitric oxide. Scientists believe this decline may contribute to the higher rates of high blood pressure seen in older adults.
The new study focused on whether beetroot juice could help restore this nitrate-nitric oxide pathway through changes in mouth bacteria.
Beetroot is naturally rich in nitrate, but other vegetables such as spinach, kale, celery, fennel, and arugula also contain high amounts.
The trial included 75 participants. Thirty-nine were younger adults under age 30, while 36 participants were in their 60s and 70s.
Each participant completed two different two-week phases. During one phase, they drank nitrate-rich beetroot juice every day. During the other phase, they drank a placebo version with the nitrate removed.
The study used a crossover design, meaning every participant experienced both conditions. Researchers separated the two phases with a two-week washout period to reduce carryover effects.
Scientists collected mouth samples before and after each phase and analyzed bacterial changes using genetic sequencing techniques.
The results showed clear changes in oral bacteria after participants consumed nitrate-rich beetroot juice. However, the changes were different between younger and older adults.
In older adults, beetroot juice reduced levels of Prevotella bacteria while increasing levels of Neisseria bacteria, which researchers associated with healthier nitrate processing and nitric oxide production.
At the same time, blood pressure fell in the older group after drinking the nitrate-rich juice. This reduction was not seen during the placebo phase.
Interestingly, younger adults also experienced microbiome changes, but they did not show the same blood pressure improvements. Researchers believe younger people may already have healthier blood vessels and stronger natural nitric oxide production, leaving less room for improvement.
Professor Anni Vanhatalo from the University of Exeter explained that older adults may benefit more because nitric oxide production naturally decreases with age.
The findings support a growing scientific theory that the oral microbiome plays an important role in cardiovascular health.
In recent years, researchers have increasingly studied how oral bacteria affect nitrate metabolism. Some scientists now believe that disrupting healthy mouth bacteria may interfere with nitric oxide production and blood pressure regulation.
Several related studies support this idea.
One 2025 study involving older adults with treated hypertension found that nitrate-rich beetroot juice increased beneficial mouth bacteria while decreasing potentially less helpful bacteria. However, that study found only limited long-term improvements in blood pressure, suggesting that medications, existing health conditions, and baseline microbiome differences may influence results.
Another 2026 pilot study found that chlorhexidine mouthwash, a strong antiseptic rinse, disrupted nitrate metabolism and reduced nitric oxide production in the stomach.
Animal studies have also shown that mouth rinses preserving nitrate-processing bacteria may support lower blood pressure compared with antiseptic treatments that destroy those microbes.
Together, the evidence suggests that the mouth microbiome may act as an important “gatekeeper” controlling how effectively the body uses nitrate-rich foods.
Researchers say this could help explain why some people respond strongly to healthy diets while others experience smaller benefits.
The findings may also influence future recommendations for healthy aging. Encouraging older adults to consume more nitrate-rich vegetables may become one practical way to support blood vessel health naturally.
At the same time, the researchers caution that beetroot juice is not a cure for hypertension and should not replace medical treatment.
Instead, nitrate-rich vegetables may work best as part of a broader healthy lifestyle that includes exercise, balanced nutrition, good sleep, and proper medical care.
Reviewing the study closely, the findings are especially interesting because they connect several different areas of health: nutrition, microbiology, aging, and cardiovascular disease.
The crossover design strengthens the research because participants acted as their own controls during different phases. The detailed microbiome analysis also provides valuable biological evidence explaining how nitrate-rich foods may work. However, the study was relatively short and included a modest number of participants.
Larger and longer studies will be needed to confirm whether these microbiome changes produce lasting cardiovascular benefits. Even so, the research strongly supports the idea that the bacteria living in the mouth may play a surprisingly important role in healthy blood pressure and healthy aging.
If you care about high blood pressure, please read studies about unhealthy habits that may increase high blood pressure risk, and drinking green tea could help lower blood pressure.
For more information about high blood pressure, please see recent studies about what to eat or to avoid for high blood pressure, and 12 foods that lower blood pressure.
Source: University of Exeter.
