But don’t rush out and change your habits just yet, says cardiologist Dr. Martha Gulati. She runs the cardiology division at the University of Arizona College of Medicine and is a spokesperson for the American College of Cardiology.
“This was a small study, 15 men, eight women,” Gulati said. “While they did see that blood pressure didn’t drop when using an antibacterial rinse in the same way as compared to people who got placebo, the question is why? And we don’t know.”
And it certainly doesn’t mean that if you used mouthwash after exercise, you blew all the heart-healthy benefits, Gulati stressed, adding that blood pressure reduction is only one benefit of exercise.
“The heart rate response, the better blood flow and all the other cardiac benefits that we get from exercise are not somehow magically blocked by these lovely bacteria that we’d like to get rid of with mouthwash,” she said.
The mouth-heart connection
Science has long known that an invasion of bad bacteria in the mouth can affect the heart. Called gingivitis, it’s an inflammation caused by a buildup of plaque, or bacteria, that can lead to red and puffy gums that can bleed easily when brushing your teeth.
“We think it’s from inflammation,” Gulati says. “Inflammation seems to be the common pathway for atherosclerosis and the rupture of plaque that ultimately causes heart attacks and strokes.”
But the mouth contains billions of bacteria at any time, and not all of them are harmful. This study was designed to look at the species of bacteria that use nitrate and convert it into nitric oxide, which when swallowed helps maintain a widening of blood vessels that leads to the ongoing effect of exercise on blood pressure.
Published in the journal Free Radical Biology and Medicine, the study asked participants to fast for the night and then run on a treadmill the next day for 30 minutes on two separate occasions. At one, 30, 60,and 90 minutes after each run they were asked to wash their mouths with either a placebo of mint-flavored water or antibacterial mouthwash. Blood and saliva samples were collected and blood pressure was measured. The whole process took about five hours on each visit.
“The main finding was that the blood flow supply to the leg muscles and the lowering-blood pressure response of exercise was significantly impaired when oral bacteria were not able to use nitrate and produce nitrite,” said lead author Dr. Raul Bescos, a lecturer in dietetics and physiology at the University of Plymouth in the UK.
In fact, using antibacterial mouthwash reduced the blood pressure-lowering effect of exercise by more than 60% during the first hour after exercise.
“This is the first evidence showing that oral bacteria play a key role in the cardiovascular response associated with exercise during the first period of recovery,” said Bescos.
The results appear to suggest that nitrate synthesis by mouth bacteria might kick-start how our bodies react to exercise, but it’s too soon to tell for sure.
“Now, we want to do large studies in clinical populations to go more in depth through the main findings of this study,” Bescos said. “These studies can help us to understand much better how exercise triggers cardiovascular health, and to apply this knowledge to improve treatments against hypertension and cardiovascular disease.”
In other words, stay tuned, more to come. In the meantime, says Bescos, visit the dentist regurlary, especially if you are under high cardiovascular risk, which includes people with obesity, diabetes and hypertension.
In addition, he says to consider avoiding “antibacterial mouthwash if this is not medically prescribed to treat some oral condition.”