Beetroot juice lowers blood pressure in older people by suppressing potentially harmful bacteria in the mouth, a study suggests.
Experts at the University of Exeter compared the responses of younger adults and older adults to beetroot juice, which is rich in dietary nitrates.
These nitrates are converted by the body into nitric oxide, which helps to relax and widen blood vessels and lower blood pressure.
The study included 39 adults under the age of 30, and 36 people in their 60s and 70s.
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For two weeks, each group were given shots of beetroot juice.
After a two-week break, during which people were given anti-septic mouthwash everyday, the groups were then given a placebo juice with the nitrate stripped out for a fortnight.
Researchers used gene sequencing to analyse the bacteria present in the mouth after each part of the trial.
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In both groups, the so-called oral microbiome – the complex ecosystem of microorganisms in the mouth – changed after drinking the nitrate-rich juice, although the effects differed.
In older people, there was a decline in common bacteria that can sometimes cause infections, and an increase in bacteria that can benefit health.
Researchers also found the older group had decreased blood pressure after drinking the nitrate-rich juice for two weeks.
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.
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“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.”
Professor Anni Vanhatalo, of the University of Exeter, added: “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.
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“The good news is that if you don’t like beetroot, there are many nitrate-rich alternatives like spinach, rocket, fennel, celery and kale.”
The study, published in the journal Free Radical Biology and Medicine, was funded by a BBSRC Industrial Partnership Award.
Dr Lee Beniston, associate director for industry partnerships and collaborative research and development at BBSRC, said: “This research is a great example of how bioscience can help us better understand the complex links between diet, the microbiome and healthy ageing.
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“By uncovering how dietary nitrate affects oral bacteria and blood pressure in older adults, the study opens up new opportunities for improving vascular health through nutrition.”
Rachael Davis