A twice-daily beetroot juice habit reversed high blood pressure in older adults within two weeks, but only by reshaping the bacteria living in their mouths. The finding, from researchers at the University of Exeter, suggests that the path to healthier blood vessels may start not in the heart but in the oral microbiome.
The study enrolled 39 younger adults under 30 and 36 adults in their 60s and 70s. Over two separate two-week phases, participants drank either nitrate-rich beetroot juice or a placebo version stripped of nitrates, with a washout period between tests. Bacterial gene sequencing revealed striking differences in how the two age groups responded.
Older adults showed a measurable drop in blood pressure after the nitrate-rich juice phase, while younger adults experienced no such benefit despite showing changes in their oral microbiome. The older group began the study with higher baseline blood pressure, a common marker of aging. That pressure fell noticeably after consuming the beet juice but remained unchanged after the placebo.
The mechanism involves a specific bacterial shuffle. In older adults, levels of Prevotella, a bacterium the researchers flagged as potentially harmful in this context, declined after beet juice consumption. Simultaneously, bacteria associated with health benefits, particularly Neisseria, became more abundant. These oral microbes perform a critical job: converting dietary nitrate into compounds that eventually produce nitric oxide, a molecule essential for relaxing blood vessels.
Nitric oxide production naturally declines with age. Older bodies generate less of this molecule, which can compromise blood vessel function and push blood pressure upward. The beet juice appears to work by reprogramming the microbial community that unlocks nitrate's benefits, essentially restoring a pathway that weakens over time.
Beetroot is not the only source. Spinach, arugula, kale, celery, and fennel all deliver dietary nitrate. Professor Anni Vanhatalo, lead researcher on the project, emphasized the practical options available. "Encouraging older adults to consume more nitrate-rich vegetables could have significant long term health benefits," she said. "If you don't like beetroot, there are many nitrate-rich alternatives."
Related research has deepened the picture. A 2025 randomized controlled study of 15 older adults with treated high blood pressure found that four weeks of beet juice selectively altered oral bacteria, raising Neisseria and lowering Veillonella, while leaving the intestinal microbiome largely unchanged. That same study revealed a complication: the blood pressure reduction did not persist in people already taking hypertension medications, suggesting the response depends on baseline health status and existing drug regimens.
Another line of investigation tested antiseptic mouthwash. A 2026 pilot study showed that chlorhexidine, a common antibacterial rinse, disrupted the mouth's ability to process dietary nitrate and reduced nitric oxide synthesis in the stomach. When people taking chlorhexidine also consumed dietary nitrate, supplementation partially preserved microbial function and nitric oxide signaling. A separate 2025 study in rats comparing chlorhexidine to a nitrate and antioxidant mouth rinse found the latter supported blood vessel health markers and lower blood pressure, though animal findings cannot be directly applied to humans.
The research opens a window into personalized nutrition. Two people eating identical nitrate-rich foods may respond very differently because their oral microbiomes process nitrate at different rates. Future work will explore how lifestyle, biological sex, age, oral hygiene practices, and baseline microbiome composition shape the effect of dietary nitrate.
Professor Andy Jones, co-author of the study, noted the broader implications. "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." He emphasized that larger trials are needed to understand individual variation in response.
The findings do not position beet juice as a replacement for blood pressure medication or other proven treatments. Instead, they suggest nitrate-rich vegetables merit a place in heart-healthy nutrition, particularly for aging adults whose bodies produce less nitric oxide naturally. The discovery that bacteria in the mouth serve as gatekeepers for a key cardiovascular pathway may reshape how researchers think about diet and healthy aging.
Author Jessica Williams: "This is a neat reminder that health breakthroughs often hide in overlooked corners of the body, and sometimes the simplest dietary changes work through surprisingly complex biology."
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