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Apparently, This Is The Absolute Worst Time To Use Mouthwash

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March 31, 2022
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After a flavorful (perhaps onion- or garlic-heavy) meal, it's common to reach for mouthwash to gargle away that pungent taste. A minty-fresh feel is far better than funky breath, am I wrong? But as health and science journalist Max Lugavere, New York Times bestselling author of Genius Kitchen, shares on the mindbodygreen podcast, you might not want to use mouthwash right after eating—in fact, that may be the absolute worst time for an oral rinse. Allow him to explain. 

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Why you shouldn't use mouthwash right after a meal (or workout).

Traditional mouthwashes with antiseptic properties are meant to sweep away all the bacteria in your mouth to give you that fresh, wintergreen feeling—but that's exactly the problem. Your oral microbiome relies on both good and bad bacteria, and it's the literal portal to your gut health. Studies have even shown that oral bacteria can actually travel toward the gut and change its microbiota1, so you don't want to obliterate everything in its path. In fact, Lugavere says oral bacteria can influence how you absorb the nutrients in your food—specifically, those heart-healthy dietary nitrates. 

See, nitrate-containing nutrients (commonly found in leafy greens) are essential precursors of nitric oxide, which is essential for immunity, healthy blood flow, metabolic health, brain health, and so much more. However, "Humans don't have the enzymes that are required to reduce nitrate to nitrite, which is then able to enter the nitric oxide pathway," says Lugavere. "We rely on oral bacteria to do that conversion," namely a species called prevotella2. So when you eliminate all of that oral bacteria with a swig of mouthwash, you're making it harder for your body to provide that essential conversion and reap the benefits of those nitrate-rich nutrients. 

"So if you're doing all the work to eat beautiful, healthy foods, and you're using [traditional] mouthwash, you're basically shortchanging the ability of your food to actually give you all of the benefits that it can," says Lugavere. In fact, when it comes to metabolic health, research has shown that those who used antiseptic mouthwash twice daily or more had an increased risk of type 2 diabetes by 50%3. Of course, this study didn't measure less frequent use, so if you use traditional mouthwash sparingly, you should be fine. "If you're using [antiseptic mouthwash] medically, I wouldn't be concerned, but it's definitely not something that you want to use on a frequent basis," Lugavere notes. 

You also never want to use antiseptic mouthwash right after a workout, he says, for a very similar reason: "Oral bacteria recycle nitric oxide," he explains. "And nitric oxide is boosted by exercise," which, again, plays a major role in metabolic health—including regulating blood pressure4. So when you sweep away all the oral bacteria post-workout, you aren't getting as much of a nitric oxide boost. Research has even found that using mouthwash after exercise can blunt the antihypertensive benefits

Of course, you can always opt for a non-antiseptic mouthwash that's gentle enough for your oral microbiome. (Find our recommendations here.) "There are other mouthwashes on the market that are not antiseptic, and those are fine, but it's the ones that are primarily alcohol that you want to avoid," says Lugavere. Or, at the very least, don't gargle them right after you eat your leafy greens or break a sweat. 

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The takeaway. 

We're continuing to learn more and more about the oral microbiome and how it affects your overall health. Here's what we know to date: Oral bacteria are important for gut and metabolic health, so you don't want to sweep them all away with an antiseptic mouthwash. A few swishes here and there likely won't cause any issues, but if you do choose to gargle, make sure it's not right after you eat or exercise.

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