How beetroot juice could help reduce blood pressure

In a short trial, beetroot juice reduced blood pressure in older adults, and shifts in mouth bacteria may help explain the effect. Younger participants did not experience the same benefit.

The results point to a link between diet, oral microbes and the blood vessels. They also suggest that how the body responds to a nutrient may depend in part on the bacteria involved in processing it.

Researchers at the University of Exeter published the study in Free Radical Biology and Medicine. The experiment used a controlled crossover design, with 39 younger adults and 36 older adults taking part so that each volunteer could act as their own comparison.

The younger group was aged 18–30, while the older group was aged 67–79. The study tested nitrate-rich beetroot juice, a matching version with nitrate removed, and a separate antiseptic mouthwash condition.

Each phase lasted two weeks and was separated by two-week gaps. During the juice periods, neither participants nor assessors knew which version had been given, reducing the chance that expectations affected the results.

Nitrate occurs naturally in beetroot and in several leafy vegetables. Some bacteria in the mouth turn it into nitrite, which the body can then use to make nitric oxide.

Nitric oxide helps blood vessels relax and widen. When vessels stay tighter, blood has a harder time flowing through the circulation, which can raise blood pressure.

The team collected mouth samples and analyzed bacterial DNA to identify which microbes were present. They also measured changes linked to nitric oxide availability and blood-vessel function.

After the nitrate-rich juice, the oral bacterial mix changed in different ways across the two age groups. In older adults, some bacteria associated with nitrate processing increased, while others declined.

Blood pressure dropped in the older group after the nitrate-rich drink, but the placebo version did not have the same effect. Younger adults did not show a similar reduction, indicating that age may shape the response.

One possible reason is that the body’s own nitric oxide production becomes less efficient with age. In that case, dietary nitrate may provide a more noticeable boost in older adults than in people whose circulation is already working well.

The study was small and short, so it did not show whether the blood-pressure effect lasts for months or whether it lowers the risk of heart attacks, strokes or other long-term outcomes.

It also does not mean that every oral bacterium is helpful or harmful in every context. Their role depends on the wider microbial community, available nutrients and a person’s overall health.

The findings add to research on nitrate-rich foods, but they do not replace prescribed treatment. They show that a common vegetable drink can affect the body’s chemistry through a partner that is easy to overlook: the microbes living in the mouth.

If you are interested in this topic, please read articles about Leafy greens and beets could prevent high blood pressure in healthy people, and Salt and heart health: does less really mean more?.

For more information, please see articles about The DASH diet is a simple way to lower high blood pressure, and Garlic could help lower high blood pressure, protect artery health.