Drinking beetroot juice promotes a mix of mouth bacteria associated with healthier blood vessels and brain function, according to a study of people between the ages of 70 and 80 conducted by researchers at the University of Exeter and Cardiff University.
Beetroot and other foods including lettuce, spinach, and celery are rich in inorganic nitrate. Many oral bacteria play a role in turning nitrate to nitric oxide, which helps to regulate blood vessels and neurotransmission, or chemical messages in the brain.
Older people tend to have lower nitric oxide production, which is associated with poorer vascular and cognitive health.
The new study involved 26 healthy older people who took part in two 10-day supplementation periods: one with nitrate-rich beetroot juice and another with nitrate-free placebo juice, which they drank twice a day.
The results showed higher levels of bacteria associated with good vascular and cognitive health and lower levels of bacteria linked to disease and inflammation. Also, systolic blood pressure dropped by an average of five points (mm Hg) after drinking the beetroot juice.
“We are really excited about these findings, which have important implications for healthy aging,” said lead author Anni Vanhatalo, professor of human physiology and director of research in the Exeter University Department of Sport and Health Sciences.
“Previous studies have compared the oral bacteria of young and older people, and healthy people compared to those with diseases, but ours is the first to test nitrate-rich diet in this way,” Vanhatalo said.
“Our findings suggest that adding nitrate-rich foods to the diet, in this case via beetroot juice, for just 10 days can substantially alter the oral microbiome (mix of bacteria) for the better,” Vanhatalo said.
“Maintaining this healthy oral microbiome in the long term might slow down the negative vascular and cognitive changes associated with aging,” said Vanhatalo.
The researchers ran tests to identify clusters or “modules” of oral bacteria that tend to thrive in similar conditions.
A module, Prevotella-Veillonella, that has been associated with inflammation was reduced after nitrate supplementation, including a decrease of Clostridium difficile, which can infect the bowel and cause diarrhea.
More research is needed to confirm the findings and see whether similar effects are found in other groups,” Vanhatalo said.
“Our participants were healthy, active older people with generally good blood pressure,” she said.
“Dietary nitrate reduced their blood pressure on average, and we are keen to find out whether the same would happen in other age groups and among people in poorer health,” she said.
“We are working with colleagues in the University of Exeter Medical School to investigate interactions between the oral bacteria and cognition to better understand how diet could be used to delay cognitive decline in older age,” she said.
Much research has been conducted into the benefits of a healthy gut microbiome, but far less is known about the oral microbial community, which plays a crucial role in activating the nitrate from a vegetable-rich diet, the researchers said.