The blood pressure-lowering effect of nitrate-rich beetroot juice in older people may be due to specific changes in their oral microbiome, according to the largest study of its kind.
Researchers at the University of Exeter conducted the study, published in the journal Free Radical Biology and Medicine, comparing responses between a group of older adults to that of younger adults.
Previous research has shown that a high nitrate diet can reduce blood pressure, which can help reduce risk of heart disease.
Nitrate is crucial to the body and is consumed as a natural part of a vegetable-rich diet. When the older adults drank a concentrated beetroot juice ‘shot’ twice a day for two weeks, their blood pressure decreased – an effect not seen in the younger group.
The new study provides evidence that this outcome was likely caused by the suppression of potentially harmful bacteria in the mouth. An imbalance between beneficial and harmful oral bacteria can decrease the conversion of nitrate to nitric oxide, which is key to healthy blood vessel function and regulation of blood pressure.
Professor Anni Vanhatalo of the University of Exeter said: “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. 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 recruited 39 adults aged under 30, and 36 adults in their 60s and 70s. Each group spent two weeks taking regular doses of nitrate-rich beetroot juice and two weeks on a placebo version with nitrate stripped out. Each condition had a two-week “wash out” period. Bacterial gene sequencing was used to analyze the oral microbiome before and after.
In both groups, the oral microbiome changed significantly after drinking the nitrate-rich juice, but these changes differed between age groups.
The older group experienced a decrease in the mouth bacteria Prevotella and an increase in health-benefiting bacteria like Neisseria. Their blood pressure dropped after the nitrate-rich juice, but not with the placebo.
Professor Andy Jones of the University of Exeter noted: “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.
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.”
Dr Lee Beniston from BBSRC added: “This research is a great example of how bioscience can help us better understand the complex links between diet, the microbiome and healthy ageing.
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.”
The study is titled ‘Ageing modifies the oral microbiome, nitric oxide bioavailability and vascular responses to dietary nitrate supplementation’ and is published in the journal Free Radical Biology and Medicine.
The study is published in Free Radical Biology and Medicine.
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