Beetroot juice changes oral microbiome and lowers blood pressure

Drinking beetroot juice twice a day can significantly lower blood pressure in older people, and researchers now believe the secret lies in the mouth.

A new study from the University of Exeter shows that the blood pressure-down effect of nitrates in the diet can work by reshaping the oral microbiome, especially by reducing specific bacteria associated with inflammation and nitric oxide production.

Diet nitrates, nitric oxide and blood pressure

Nitrates are abundant in vegetables such as beetroot, spinach and arugula, and are known to support vascular health by increasing nitric oxide (NO) levels in the body. It does not help dilate blood vessels, improve blood flow and lower blood pressure. However, this nitrate conversion relies on oral bacteria, which may change with age.

In this double-blind, placebo-controlled study, 75 healthy adults were divided into two groups: under 39 years of age 30, 36 years of age, between 67 and 79 years of age. Each participant was given a nitrate-rich beetroot juice or a placebo version without nitrate, while a nitrate-free one was between two weeks and a two-week wash time. The third arm includes a bactericidal mouthwash, known to destroy oral bacteria.

Elderly people show stronger blood pressure response

Although the two age groups showed changes in their oral microbiome after eating beetroot juice, only the older adults had decreased blood pressure. Their systolic blood pressure dropped by an average of 7 mmHg, which is a clinically meaningful reduction.

• Older people start with higher blood pressure (126/80 mmHg)
• Plasma nitrite levels only significantly increased in older groups
• Changes in blood pressure are related to specific metastasis of oral bacteria

The most significant microbiome transfer in the elderly is the reduction of prevotella and veillonella species, where bacteria convert nitrates to ammonia instead of nitric oxide. These bacteria are essentially beneficial ways to “short circuit”. In contrast, nitrate supplementation promotes Neisseria levels, which enhances nitrogen oxide production and is associated with vascular health.

The results of young participants are different

Despite similar changes in oral bacteria, the blood pressure in young people did not drop significantly. Their baseline level is already low, with an average of 117/72 mmHg. The authors of the study suggest that young people may rely more on their own nitric oxide synthase pathways, which decline with age.

Mouthwash reduces vascular response

Interestingly, bactericidal mouthwash disease reduced oral microbiome diversity in young participants and led to a reduction in flow-mediated dilation, a measure of vasoreactivity. This suggests that regular use of bactericidal mouthwash may interfere with nitric oxide production and cardiovascular function.

“We know that a nitrate-rich diet has health benefits and older people produce their own nitric oxide as they age.” “Encouraging older people to consume more nitrate vegetables can have significant long-term health benefits.”

Effects on diet, aging and inflammation

In addition to blood pressure, studies have shown that nitrates in the diet can play a broader role in managing age-related inflammatory states. The presence of Pretoria and Veillonella in older participants after supplementation may have a downstream effect on chronic inflammation, contributors to diseases such as arthritis and cognitive decline.

“This study shows that nitrate-rich foods change the oral microbiome in ways that may lead to reduced inflammation and lower blood pressure in older people,” said co-author Professor Andy Jones.

Magazine: Free radical biology and medicine
doi: 10.1016/j.freeraadbiomed.2025.07.002

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