It’s a common myth that the more sugar you eat, the more likely you are to get cavities. But it’s not always so, says Tufts University professor of nutrition and oral health Carole Palmer. Writing with colleagues in the July/August issue of Nutrition Today, she explains that it’s not in fact the amount of sugar you ingest that matters, but rather the total time that the sugar spends in contact with your teeth. The result: downing a sports drink in two minutes after a gym session puts your teeth at far less risk than if you sip on an equally sugary drink all throughout the afternoon.
The science is simple. Dental plaque is a film of bacteria and salivary proteins that forms on the teeth, Palmer and colleagues write. When that plaque then comes in contact with sugar, the bacteria in it will ferment the sugars into acids that break down tooth enamel, allowing cavities.The authors write: “All simple carbohydrates — glucose, fructose, maltose, and, to a lesser extent, lactose, and sucrose — can be metabolized by [cavity-forming] bacteria.” More complex carbohydrates, i.e. the starches like those in rice and bread, can also be fermented by the bacteria in our mouths, if we keep the starch in our mouths long enough for saliva to break it down into simple sugars. (As a kid, you may have experimented with keeping a cracker in your mouth until it started to taste sweet.)
To prevent cavities, then, you should limit the total time that sugar spends in your mouth. (Remember, of course, that gulping down sugar may not be wonderful for the rest of your body either, so it might not hurt to start by cutting sugar intake in general.) Look out especially, however, for common culprits that you don’t normally consider to be sweet treats — things like a cup of coffee with sugar that you sip on over an hour or more. You can also help your mouth to process the sugars quickly by saving treats for dessert right after meal times, when you already have a lot of saliva clearing out your mouth, or by washing them down with a glass of water.