Mouthwash Can Mess With Your Workout, A New Study Says, & Here’s How

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You might already know that your blood pressure tends to get lower after you work out, and this is generally a good thing. As you're strengthening your heart and getting your blood vessels accustomed to the larger blood volumes you need to pump when you're getting your gym on, you can often reduce high blood pressure through exercise. But a new study says that if you rinse your mouth with mouthwash after a workout, you may reduce those blood pressure-lowering benefits.

The study, published in the journal Free Radical Biology and Medicine, was focused on a particular type of bacteria that lives in your mouth. And before you panic, remember that you have billions of oral bacteria in your mouth at any given time, and most of them are friendly to your body. One such species of friendly bacteria takes the compound nitrate and converts it into nitric oxide, which helps your body dilate your blood vessels.

And this is quite relevant after your workout, because when nitric oxide helps maintain the widening of your blood vessels that started during your workout. This widening is one of the mechanisms that helps working out lower your blood pressure, because pressure is lower when blood has a wider, less constricted space to travel through.

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So what's mouthwash got to do with it? Well, the study asked that participants do 30 minutes of fasted cardio. After intervals of 30, 60, and 90 minutes post-workout, participants rinsed their mouths with either mint-flavored placebo water or actual antibacterial mouthwash. Everyone's blood pressure was subsequently measured, and those that rinsed with mouthwash experienced a much smaller drop in post-exercise blood pressure than their placebo peers.

In other words, rinsing with mouthwash takes away at least some of the blood pressure-lowering benefits of a workout. Because if you get rid of the bacteria that convert nitrates into nitric oxide, there won't be a lot of nitric oxide available to help keep those blood vessels wide and flowing. And this is giving exercise scientists new insights into exactly how connected everything in your body is.

This learning has huge implications for cardiovascular health generally. Because your blood pressure drops naturally after a single workout, but exercise also lowers your overall blood pressure over time, according to the American Heart Association. And, according to a 2018 study published in the Journal of the American Society of Hypertension, there is a direct connection between how much your blood pressure drops after a single bout of exercise to how much exercise can help your blood pressure drop in the long run.

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The more effective each single workout is at dropping your blood pressure, the 2018 study found, the greater the effectiveness of exercise overall at lowering your daily blood pressure. So the potential ramifications of the new mouthwash study are huge: if you're trying to improve your cardiovascular health, it might be beneficial to avoid using antibacterial mouthwash unless you need it for a specific medical reason.

Because even though it might feel like what's going on in your mouth has nothing to do with what's going on in your cardiovascular system, the opposite may well be true. According to Harvard Health Publishing, there are many biological factors that connect oral health to heart health, including oral bacteria traveling through blood vessels to the rest of the body, including the heart. So given this new study's suggestion that you need certain oral bacteria to help exercise lower your blood pressure most effectively, it may time to check in with your dentist about what's best for your mouth and your heart.