An interesting recent study has suggested that the beneficial blood pressure reduction that is experienced after working out is actually kickstarted by molecules that are released by bacteria in the mouth. The research was led by scientists from the University of Plymouth. The research has concluded that antibacterial mouthwash can end up removing helpful oral bacteria as well and thus hampers the positive post-exercise cardiovascular effects.
Raul Bescos, the lead author of the study, said, ‘Scientists already know that blood vessels open up during exercise, as the production of nitric oxide increases the diameter of the blood vessels (known as vasodilation), increasing blood flow circulation to active muscles. What has remained a mystery is how blood circulation remains higher after exercise, in turn triggering a blood-pressure-lowering response known as post-exercise hypotension.’
Upon degradation, nitric oxide becomes a compound known as nitrate. Previous research has already demonstrated that certain species of oral bacteria actively converts nitrate into a molecule that is known as nitrite. This process is crucial because nitrite is absorbed throughout the gastrointestinal tract. It enters the bloodstream and is then eventually converted back into nitric oxide. The latest research started off with testing a hypothesis whether the oral nitrate/nitrite pathway is responsible for regulating the sharp reduction of blood pressure that is visible even after hours of working out.
Bescos said, ‘We wanted to see whether blocking nitrate’s ability to convert into nitrite by inhibiting oral bacteria would have any effect on post-exercise hypotension.’ The experiment featured 23 healthy adults that ran on a treadmill for about half an hour. After the exercise, participants were asked to rinse their mouths on four occasions over two hours with either a placebo or an antibacterial mouthwash. Blood pressure was measured prior to working out and then after an hour and two hours after the workout. Saliva and blood samples were also collected.
The results are quite comprehensive; systolic blood pressure measurements were acutely lower after an hour of exercise for the placebo group. On the other hand, the mouthwash had reduced the blood-pressure-lowering effect of exercise by 60%. Furthermore, the nitrite blood levels were only found in the placebo group, thus highlighting that this particular molecule is responsible for creating post-exercise hypotension. It was also concluded that its production could be hampered severely by affecting the bacteria’s activity in the mouth.
Craig Cutler who is the co-author on the study, said, ‘These findings show that nitrite synthesis by oral bacteria is hugely important in kickstarting how our bodies react to exercise over the first period of recovery, promoting lower blood pressure and greater muscle oxygenation. In effect, it’s like oral bacteria are the ‘key’ to opening up the blood vessels. If they are removed, nitrite can’t be produced, and the vessels remain in their current state.’
Cutler further adds, ‘The next step is to investigate in more detail the effect of exercise on the activity of oral bacteria and the composition of oral bacteria in individuals under high cardiovascular risk. Long-term, research in this area may improve our knowledge for treating hypertension – or high blood pressure – more efficiently.’ The research has been published in the journal Free Radical Biology and Medicine.