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Using mouthwash after exercise can lead to a strange thing

It is often shown in television advertisements that when people use mouthwash, immediately all the unpleasant bacteria in their mouths is removed assuring them of their dental hygiene. But the important questions are what actually takes place, when a cap of antibacterial chemical is used and what it really does in the body? What is its effect in other kinds of microorganisms that are beneficial to health?

In an experiment conducted by researchers from the UK and Spain, they found that using mouthwash after exercising can minimize one benefit of exercising: lowering blood pressure. The work appears in Free Radical Biology and Medicine journal.

Our blood vessels open in response to the production of nitric oxide during exercise, increasing the diameter of blood vessels. It increases blood flow circulation to active muscles and this process is called vasodilation. Researchers believed that circulation stays high (blood pressure is lowered) only during exercise for a long time but recently, facts have shown that it takes place even after exercise because of interaction with nitrate, which forms when nitric oxide degrades.

Raul Bescos, physiology specialist from Plymouth University explained that research has shown that nitrate can be absorbed in the salivary glands and excreted with saliva. He also added that nitrite molecule which is produced by a species of bacteria in the mouth using nitrate can strengthen the production of nitric oxide in the body. Nitrite gets absorbed into the blood circulation and reduces back to nitric oxide, once produced and swallowed with saliva. It keeps blood vessels wide and lowers blood pressure.

This biological mechanism can be substantially disrupted if anti-bacterial mouthwash gets added into the post-exercise mix according to this study. 23 participants ran on a treadmill for 30 minutes. They were asked to wash their mouth with either an antibacterial mouthwash or a mint-flavoured placebo, immediately after the exercise and also after an interval of 30,60 and 90 minutes. Their blood pressure was taken during the exercise and after their rest period.

The conclusions showed that the average reduction in systolic blood pressure in the placebo group was –5.2 mmHg (millimetres of mercury) at one hour after the treadmill session. The mouthwash-using group showed an average of -2.0 mmHg at the same time, meaning the use of the antibacterial mouthwash (0.2 percent chlorhexidine) had lowered the systolic blood pressure reduction by more than 60 percent. The mouthwash group showed no sign of reduction in the blood pressure, two hours after the treadmill session whereas the placebo group still showed a significant reduction compared to the pre-exercise values.

The authors explained in their paper that this is the first evidence demonstrating the nitrate-reducing operation of oral bacteria is significant for inducing an acute cardiovascular response to exercise during the period of recovery. Consuming antibacterial chemicals that randomly eliminate the microbes in the mouth could obstruct important biological processes necessary for good health and this study reminds that not all bacteria are necessarily bad for us.

Craig Cutler one of the team nutritionists said that these results show that nitrite synthesis by oral bacteria is very important in reactivating how our bodies react to exercise over the first period of recovery, promoting lower blood pressure and greater muscle oxygenation. He also added that nitrite can’t be produced and vessels will remain in their current state if the oral bacteria will be removed.

Journal Reference: Free Radical Biology and Medicine journal