Why do runners get more cavities?

At mile 18 of a marathon, some of the fittest people on earth are reaching into their running vests for a fistful of Nerds Gummy Clusters. Plenty of elite runners swear by it, and their rationale is that past ninety minutes, you burn through carbohydrates faster than last night’s pasta can cover, and candy delivers a gel’s worth of fast carbs for less money, less weight, and better taste.

I’m not going to debate that point, at least, not in this newsletter. Whether candy beats a gel isn’t my department. But teeth and the oral microbiome are.

The moment you start breathing through your mouth, whether on a run, on the bike, hitting the StairMaster at your gym, your mouth pH can drop.

A happy tooth is a tooth bathed in saliva, which is why runners, hikers, and any athlete who breathes through their mouth from time to time, are more prone to cavities than those who are strictly nasal breathers.

Unfair, isn’t it? Nobody warned you that a new gym habit can come with new dental work. But it doesn’t have to be that way…

My must-haves for athletes (whether you’re training for Ironman or just casually hitting the treadmill in your garage)

✔️ Electrolytes. You already know they hydrate you, but what you might not have realized is that they help fight cavities. Saliva is your enamel’s repair kit. It ferries the calcium and phosphate that rebuild the surface and the buffers that neutralize acid, and it can’t do either without minerals. As an avid mountain biker, I’m always vetting different electrolyte products, and these are my all-time favorite.
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✔️ Nitric oxide mints. The bacteria on the back of your tongue turn the nitrate in your food into nitric oxide, the molecule that widens your blood vessels and sends more oxygen to working muscle. These mints feed that pathway on demand. This matters more with every passing decade. Your body makes less nitric oxide as you age, and blood vessels stiffen and turn less responsive—part of why the pace that felt easy at 35 leaves you winded at 55. While we can’t stop that clock, the nitrate-to-nitric-oxide pathway is one of the few levers still in our hands (or, rather, our mouths)
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✔️ Nano-hydroxyapatite prebiotic toothpaste. Between the mouth breathing and the acidic fuel, training leaves your enamel under repeated attack. Brushing with an oral microbiome friendly hydroxyapatite a day is how you defend it: it’s the mineral your teeth are already made of. And in a recent peer-reviewed study out of UT Health San Antonio, it matched prescription-strength (5,000 ppm) fluoride.
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✔️ Xylitol gum or mints. A piece after your workout switches your saliva back on the second you stop. And S. mutans, the cavity bug, can’t ferment xylitol, so the same piece starves the bacteria you just fed with that gummy pack.
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✔️ Mouth tape. There’s a reason some of the best World Cup soccer players both sleep and train with mouth tape. Tape keeps you breathing through your nose, which helps sleep quality, while at the same time protecting those nitrate-to-nitric-oxide bacteria mentioned above, and protecting those teeth too.
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And if you must eat the candy—keep this in mind: It’s not the amount of sugar in a gel that gets you, it’s the minutes it spends on your teeth. A pack of clusters nursed over an hour does more damage than the same sugar eaten at once. Always, always swish with water after eating candy, aiming to dislodge any sticky bits left behind.

Believe it or not, your mouth is part of the machinery that builds your fitness, and almost nobody thinks to tune it, until now!

– Dr. B

P.S. More on the sneaky causes of adult cavities here.

P.P.S. Were you breathing through your nose while reading this newsletter? If you can’t pull a full breath through your nose even at rest, it’s worth having checked. A dentist trained in airway will know exactly what to look for, and you’ll find one in my Functional Dentist Directory.