High blood pressure is considered one of the primary risk factors for heart disease, stroke, and vascular complications, especially in old age. Now, a new study from the University of Exeter in the UK suggests that a relatively simple dietary change may help some people improve their blood pressure, and perhaps even through a particularly surprising place: Oral bacteria.
The researchers found that older adults who drank nitrate–rich beetroot juice twice a day for two weeks managed to significantly reduce their blood pressure. Among the younger participants, however, this effect was barely observed.
According to the researchers, this is the largest study to date that examined the link between dietary nitrates, oral bacteria, nitric oxide production, and vascular function at different ages.
<br>Why oral bacteria specifically?
Most people do not think of their mouth as a factor that affects blood pressure, but in recent years more and more studies indicate that the bacteria living in the mouth play a particularly important role in vascular health.
Nitrates, which are naturally found in various vegetables, undergo an initial breakdown process in the mouth by certain bacteria. Subsequently, the body converts them into nitric oxide, an important molecule that helps dilate blood vessels and regulate blood pressure.
When the composition of oral bacteria changes for the worse, the body's ability to produce nitric oxide is impaired, and therefore blood vessels may also function less well.
The researchers from the University of Exeter sought to examine whether a supplement of nitrates through the diet could alter the oral bacteria population and thereby affect cardiovascular health.
A total of 75 people participated in the study. 39 of them were under the age of 30 and 36 additional participants were in their 60s and 70s. All participants underwent two different phases of two weeks each. In one phase, they drank nitrate–rich beetroot juice twice a day. In the second phase, they received an identical placebo drink from which the nitrates were removed.
Between the two phases, the researchers waited an additional two weeks to "reset" the study conditions. During the experiment, samples were taken from the participants' oral cavity to check which bacteria were present there before and after the consumption of the juice.
What did the researchers discover?
Changes in the composition of oral bacteria were recorded in all participants after drinking the beetroot juice, but among the older adults, the change was particularly significant.
The researchers found a decrease in the abundance of a group of bacteria called Prevotella, which is considered less desirable in certain contexts, and a concurrent increase in the abundance of bacteria such as Neisseria, which have been previously linked to positive health effects.
But the most significant finding was the decrease in blood pressure among the older adults who drank the nitrate–rich beetroot juice. This decrease was not observed after drinking the placebo drink, nor was it seen among the young people in the study.
According to the researchers, it is possible that older people benefit more from this process because as people age, the body naturally produces less nitric oxide.
Not only beetroot
Although beetroot juice was at the center of the study, the researchers emphasize that beetroot is not the only source of nitrates. Vegetables such as spinach, arugula, celery, fennel, and kale also contain relatively high amounts of natural nitrates.
According to the researchers, a diet rich in such vegetables may be a relatively simple way to maintain vascular health over the years.
One of the interesting aspects that emerged from the study is actually related to oral hygiene. Previous studies found that strong antiseptic mouthwashes might harm the good bacteria involved in the process of converting nitrates into nitric oxide.
In an additional pilot study published this year, it was found that the use of a chlorhexidine–type antiseptic mouthwash harmed this metabolic process and reduced the production of nitric oxide. The potential implication is that the delicate balance of oral bacteria influences much more than what was previously thought.
Can beetroot juice replace medications?
The researchers emphasize that beetroot juice is not a substitute for medical treatment or blood pressure medications, and it is certainly not recommended to stop any existing medical treatment following the study.
However, they believe that the findings reinforce the understanding that diet can affect vascular health in ways that are more complex than previously thought. According to them, in the future it might be possible to tailor dietary recommendations also according to each individual's personal microbiome composition.
The researchers are now planning larger studies that will examine how age, sex, lifestyle, and oral hygiene habits affect the response to dietary nitrates. Until then, it seems the core message is relatively simple: A diet rich in vegetables may be beneficial not only for the heart and weight, but perhaps also for the tiny bacteria that live in our mouth.