Beetroot Juice Helps Older Adults Lower their Blood Pressure in Just Two Weeks

According to the largest study of its kind, the blood pressure-lowering effect of nitrate-rich beetroot juice in older people could be due to specific changes in their oral microbiome. Researchers at the University of Exeter conducted the study, which was published in the journal Free Radical Biology and Medicine, comparing the responses of a group of older adults with those of younger adults. Previous research has shown that a nitrate-rich diet can lower blood pressure, which can help reduce the risk of heart disease.

The Benefits of Nitrate for the Aging Body

Nitrate is essential for the body and is absorbed as a natural component of a vegetable-rich diet. When the older adults drank a concentrated beetroot juice “shot” twice a day for two weeks, their blood pressure dropped—an effect that was not observed in the younger group. The new study, funded by a BBSRC Industrial Partnership Award, provides evidence that this result was likely caused by the suppression of potentially harmful bacteria in the mouth. An imbalance between beneficial and harmful oral bacteria can reduce the conversion of nitrate (which is abundant in plant-rich diets) into nitric oxide. Nitric oxide is crucial for healthy blood vessel function and thus for regulating blood pressure.

The study’s author, 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 such as heart attack and stroke. Encouraging older adults to eat more nitrate-rich vegetables could have significant long-term health benefits. The good news is that there are many nitrate-rich alternatives such as spinach, arugula, fennel, celery, and kale if you don’t like beetroot.”

Beetroot Juice Promotes the Growth of Health-Promoting Bacteria in Older People, Thereby Lowering Blood Pressure

The study involved 39 adults under the age of 30 and 36 adults in their 60s and 70s, who were recruited through the NIHR Exeter Clinical Research Facility. The study was supported by the Exeter Clinical Trials Unit. Each group regularly consumed nitrate-rich beetroot juice for two weeks and a placebo version of the juice from which the nitrate had been removed for two weeks. Between the two phases, there was a two-week “washout phase” to cleanse the body. The team then used a bacterial gene sequencing method to analyze which bacteria were present in the mouth before and after each phase. In both groups, the composition of the oral microbiome changed significantly after drinking the nitrate-rich beetroot juice, but these changes differed between the younger and older age groups.

In the older age group, consumption of the nitrate-rich juice led to a significant decrease in the oral bacteria Prevotella and an increase in the growth of bacteria known to be beneficial to health, such as Neisseria. The older group had higher average blood pressure at the start of the study, which decreased after consuming the nitrate-rich beetroot juice, but not after consuming the placebo. According to co-author Professor Andy Jones of the University of Exeter, this study shows that nitrate-rich foods alter the oral microbiome in a way that can lead to less inflammation and lower blood pressure in older people. This paves the way for larger studies investigating the influence of lifestyle factors and biological sex on human response to nitrate supplementation. By revealing how dietary nitrate affects oral bacteria and blood pressure in older adults, the study opens up new possibilities for improving vascular health through diet.