Sunday, July 11, 2021

Mouthwash Reduces Exercise Benefits

I brush my teeth at least 3 times a day, but usually do not use mouthwash. Actually I do, I grind my teeth at night and wear a night splint so as not to wear out the enamel in my teeth. Sometimes, I soak my splint in mouthwash to have that fresh minty sensation when I'm wearing it.

Do you use mouthwash? A study (Cutlet et al, 2019) found a surprising link between mouthwash and nitric oxide levels. Yes, using anti-bacteria mouthwash can affect your nitric oxide levels.

We know that exercise helps to lower your blood pressure (BP). When we exercise, the cells in our blood vessels and muscles produce nitric oxide. Nitric oxide helps widen our blood vessels and lowers our BP. This continues after exercise and our BP remains low. The bacteria in our mouth helps to recycle nitrates produced during exercise into nitric oxide. 

So if you use mouthwash to kill those helpful microscopic bugs, you are also spitting them down the drain and this can affect your blood pressure. This can also mess with your sporting performance.

Researchers from that study (Cutler et al, 2019) had a group of healthy man and women  run two 30-minute treadmill tests. After the first run, the runners rinsed their mouths with either an anti-bacterial (0.2 percent chlorhexidine) mouth wash or an inactive, mint flavored rinse.

After the second run, their mouth washes were switched. Neither the runners nor researchers knew which mouthwash the runners were rinsing with each time. BP and blood samples of the runners were taken before each session and two hours after the run.

When the mint-flavored placebo rinse was used, their systolic BP ( the highest BP level when the heart is squeezing and pushing oxygenated blood into circulation) was reduced by an average of 5.2 mm Hg one hour later. However, when the anti-bacteria mouthwash was used their BP fell by only 2mm Hg (> 60% less than the placebo) over the same time period.

What was worse was that the BP lowering effects completely disappeared  after two hours when using the anti-bacteria mouth wash. 

Moreover, their blood nitrate levels did not increase after the runners used the anti-bacteria mouthwash. However it spiked when they used the placebo rinse.

This shows that oral bacteria play a key role in the cardiovascular effects of exercise, specifically the vasodilation and lower BP after exercise. The nitrates formed during exercise are absorbed by the salivary glands and secreted in the mouth. Oral bacteria in the mouth then reduces it to nitrite in the recovery phase after exercise. Once the nitrite is swallowed, it can be absorbed into the bloodstream to form new nitric oxide to help sustain the blood supply to previously active tissues.

Since mouth wash lowers nitrite availability, this may impair cardiovascular response associated with exercise, although more research is needed to study this in greater detail.

Since we already know that runners and other endurance athletes  tend to have poorer dental health, it may not be wise to rinse your mouth with anti-bacteria mouth wash. Instead, eat less sugar and brush your teeth regularly to maintain good dental hygiene . Otherwise, you may not get the most out of the the vessel widening, circulation boosting benefits from exercising. This would be a real pity.


Cutler C, Kiernan M, Willis JR et al (2019). Post-exercise Hypotension And Skeletal Muscle Oxygenation Is Regulated By Nitrate-reducing Activity Of Oral Bacteria. Free Rad Biol Med. 143: 252-259. DOI: 10.1016/j.freeradbiomed.2019.07.035

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