Your mouthwash can have a bizarre effect on how exercise affects your body, suggests a new study this week. The study found that ingesting mouthwash may prevent exercise from lowering your blood pressure as usual. Strange as it may sound, the results highlight the importance of bacteria living in our mouths.
According to the study's author Raoul Beskos, a nutritional physiologist based at Pilgrim University in the UK, his team is not really interested in studying the effects of mouthwashing on exercise.
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Read more Read more ] Exercise has long been known to lower our blood pressure, in part by making our bodies produce more nitric oxide, which opens and dilates our blood vessels. But even after we finish jogging and stop producing excess nitrous oxide, our blood pressure tends to stay lower than it has been for hours, a phenomenon known as post-exercise hypotension. There are various theories as to why this happens, but no one has fully invented
One theory that Beskos and his team, based on other studies, include the natural microbial environment or microbiome of our mouths. A by-product of nitric oxide, called nitrate, is often ingested by some bacteria in the mouth. These bacteria then process the nitrates into another chemical called nitrite, which is absorbed into the body when we ingest saliva, and some of it is converted back into nitrous oxide. They theorized that this process receives enough nitrous oxide back into our bloodstream, where it helps keep our blood pressure low. Mouthwash was simply a way for them to test their theory.
"We used this approach because we had evidence that it was an effective method of inhibiting the activity of oral bacteria, and in particular nitrite synthesis in the mouth," Beskos told Gizmodo via email.
The team recruited 23 healthy adults for their experiment. Volunteers were forced to run on a treadmill for half an hour on two separate occasions, after which they were kept under close surveillance and monitored for two hours. During these two hours, they were randomly assigned to wave either mouthwash or placebo; on the second voyage they took whatever liquid they had not for the first time.
When people took mouthwash as opposed to placebo, the team found that their blood pressure was not reduced by as much. By the two-hour mark, the effect had completely disappeared after the exercise. The mouthwash probably does not kill the bacteria enormously in the mouth, as the diversity of the microbiome remains unchanged. But it seems to drastically reduce their ability to produce nitrites and this has led to lower levels of nitrite in people's saliva and blood.
The team's findings have been published in Free Radical Biology and Medicine.
Other studies have already shown that this mouthwash may interfere with the production of nitrites by our bacteria in the mouth, Beskos said. "However, this study shows for the first time that this time of oral nitrates / nitrites is a key element in the cardiovascular benefits of exercise."
Of course, as Beskos notes, most people probably don't drop a water bottle for mouth every time they finish jogging. But there are some broader implications of their research (provided their results are consistent with other larger studies).
On the one hand, we know that some people with high blood pressure have problems lowering it, even when they seem to follow their doctor's advice and exercise more. People with high blood pressure may also be more likely to have gum disease, which can affect their oral microbiome. Therefore, it is not improbable to think that the latter condition may affect their blood pressure, although more research is needed to prove this connection, Beskos said. While mouthwashing has not been a key part of his team's study, other studies this year suggest that regular use may even increase blood pressure in humans, not just weaken the benefits of exercise.
As with this study, the authors theorize that this effect was caused by how mouthwashing affected bacteria capable of producing nitrites.
Given all this, it is worth exploring further whether mouthwashing really does more good than bad for us. But most of all, said Beskos, the study is just further evidence that our oral health is more related to our lives than we would imagine.
"The main message of this study is that we need to pay more attention to oral conditions in order to get maximum results from the exercises," he said.