Q&A: How Do I Prevent Cavities With My Diet?

Q: I brush daily and don’t eat any candy, but I still had 3 cavities at my last dental check-up.  Could my diet somehow be contributing?

A: Dental cavities are holes in the enamel of your teeth caused by acids secreted by bacteria that live in your mouth.  These acids are the byproduct of bacterial digestion of certain carbohydrate foods, and are more likely to cause damage when exposure to these foods is (1) frequent and (2) prolonged.  As you can imagine, then, your diet can absolutely contribute to dental cavities, even if you don’t eat candy.

Proteins and fats cannot be broken down by oral bacteria and therefore do not contribute to cavities; milk protein in particular appears to have a mitigating effect on oral acid production, even in the presence of simple sugars. Some foods and ingredients may actually help protect teeth from cavities; these include xylitol (a sugar substitute found in sugarless gums) and aged cheeses like cheddar or Swiss.

The most “cariogenic” (cavity-promoting) foods are simple sugars, like sucrose (table sugar) and fructose, since they are quickly broken down in the mouth and are therefore more accessible to the oral bacteria.  Cooked starches, such as those found in bread, crackers, cereal, chips/pretzels, pasta and fries, are also broken down by bacteria in the mouth, but they take much longer. Therefore, these foods are most likely to contribute to cavities if you’re constantly snacking on them or they get stuck in your teeth so that bacteria have the time to  break them down.

Given these facts, you won’t be surprised to learn that research shows higher sugar intake–and not just from candy–is associated with increased incidence of cavities.  But what may surprise you is that WHEN you consume your sugar may matter, too. Sugar eaten with meals appears not to contribute to cavities nearly as much as sugar eaten in between meals, for example.  This has to do with a number of factors, including the presence of protein and fat  in addition to the carbohydrate, as well as higher saliva production that helps clean teeth and buffer the acidic mouth environment.

So how can you adjust your eating habits to help reduce the risk of cavities?

  • If you can’t brush after eating, chewing sugarless gum that contains xylitol after a meal or snack can have a cavity-inhibiting effect and is a good backup plan.
  • Eating fewer foods and snacks with added sugar is a good start, both for your teeth and your overall health.  When you do choose to splurge, having your sweetened foods WITH a meal rather than alone in between meals is a better choice from your teeth’s perspective.
  • “Grazing” all day on food rather than eating defined mixed meals can create a constantly acidic environment in your mouth.  If you do snack in between meals, pair carbohydrate foods with protein-rich ones, like crackers or chips with cheese or peanut butter.
  • Be sure to wash down in-between meal snacks with a glass of water, particularly ones that contain sugar, have sticky textures (like dried fruit or Fig Newtons), or are very starchy and likely to get stuck in the teeth (like pretzels).
  • Sweetened beverages literally bathe the teeth in sugar and are best avoided.  However, if you do choose to drink sweetened beverages (juice, coffee and tea count here), be aware that slowly sipping on them over a prolonged period of time is more likely to contribute to cavities than drinking them in a single sitting.  If you’re a sipper, using a straw can help minimize contact between the sugar and your teeth.


Tamara Duker Freuman, MS, RD, CDN

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