When patients come to me with cavities, they always expect me to lecture them about brushing and flossing more. And yes, those are important. But what really surprises them is when I start talking about their diet. Not just the obvious stuff like candy and soda—I’m talking about when they eat and what they choose to put in their mouths.
My Two-Rule System for Dental Health
Here’s what I tell every single patient: there are two ways diet plays into the health of your teeth. That’s when you eat and what you eat.
Most people have never thought about the timing, but it’s huge. When you eat is very important because it’s going to be as close as it can be to when you brush next. So if you eat breakfast and then you brush afterwards, excellent. Then diet isn’t going to play a whole lot into your dental health because you’re going to brush all that food off your teeth. But if you’re going to eat and then not brush for 5 hours later, then it might be a good idea to select something that doesn’t cause as much damage to your teeth.
This isn’t just my opinion—the American Dental Association recommends waiting at least 60 minutes after eating acidic foods before brushing, and research shows bacteria in dental plaque produces acids that attack tooth enamel for at least twenty minutes after eating. So timing really does matter.
The Bacteria Are Always Waiting
Now let’s talk about the second part—what you eat. What you eat is what we get to next. And what you eat is carbohydrates. Carbohydrates feed the bacteria that sit on your teeth. They’re waiting there patiently for you to eat so they can eat. And once they eat, they produce an acid when they eat carbohydrates. And that acid makes holes in the teeth. And sadly, the holes in your teeth then are called cavities. And that’s how you get cavities.
I know this sounds simple, but it’s exactly what happens. Dental caries affects 2.5 billion people worldwide, and studies confirm that simple carbohydrates promote overgrowth of cavity-causing bacteria like mutans streptococci and lactobacilli. The bacteria literally eat what you eat, then they excrete acid that dissolves your teeth.
Your Enamel Is Tougher Than You Think (But Not Tough Enough)
Let me tell you something that might surprise you. Enamel is the hardest substance in the whole human body. It’s stronger than bone. But that acid that those bacteria produce, they cause damage to the enamel so much that they make holes in the enamel. And once there’s holes in the enamel, then the bacteria have access to the actual tooth itself.
This is what frustrates me—your enamel is incredible. It’s 96% hydroxyapatite compared to bone’s 70%, making it the hardest biological material in your body. Yet despite this natural armor, bacterial acids can still break through it when we keep feeding those bacteria.
Think of Your Tooth Like an M&M
I use this analogy with my patients all the time because it really helps them understand what’s at stake. I imagine a tooth is like an M&M with a hard candy shell on the outside and then a soft chocolate on the inside. And that hard candy shell is the enamel. And the soft chocolate is the yummy part that the bacteria can eat without the help of producing any acid.
Once they make a hole in the enamel, they have access to the tooth without the help of any foods. So we don’t want them to cross that barrier.
This is why enamel protection is so critical. Once Streptococcus mutans—the main cause of dental decay—breaches the enamel barrier, that soft interior becomes vulnerable to rapid destruction. At that point, the damage accelerates quickly because the bacteria don’t need your diet anymore—they can just feast on the tooth itself.
My Favorite Foods for Your Teeth
So what should you eat? Select foods in your diet that don’t have carbohydrates. My favorite food of all would be a bowl of broccoli because broccoli doesn’t have any carbohydrates. My second favorite would be a cold cut, a piece of turkey, smoked turkey, nothing on it. Just roll it up and eat it. Don’t eat it with bread because guess what? Bread has carbohydrates.
You have to select a food for the health of your teeth that doesn’t have carbohydrates in it or doesn’t have simple sugars. We don’t obviously want a cookie because a cookie has both carbohydrates and simple sugars in it. And the bacteria on your teeth can eat those and cause damage to your teeth. So my favorite food for dental health would be a bowl of broccoli. My second favorite would be some kind of protein. Like if you just ate a slab of steak or a pork chop, that is not going to be causing any problems with your teeth. You can make yourself full and not ever get a cavity.
Research backs this up—higher glycemic index foods cause greater plaque pH drops and more acid production. Even healthy carbohydrates can feed harmful bacteria when consumed frequently.
The Timing Game Changes Everything
Here’s the thing about timing that most people don’t realize. If you eat breakfast and then you brush afterwards, excellent. Then diet isn’t going to play a whole lot into your dental health because you’re going to brush all that food off your teeth.
But if you’re going to eat and then not brush for 5 hours later, then it might be a good idea to select something that doesn’t cause as much damage to your teeth. Plaque begins building up just 20 minutes after eating, so those hours between eating and brushing are when the real damage happens.
The Global Impact of Getting This Wrong
When I see patients who don’t understand this connection between diet and dental health, I’m not just worried about their individual teeth. Dental disease costs $387 billion globally each year. That’s money that could be saved if more people understood these simple principles.
The good news? The WHO confirms that dental caries can be prevented by avoiding dietary free sugars, and they recommend limiting free sugar intake to less than 5-10% of total calories. It’s completely preventable.
What I Want You to Remember
Look, I know this might sound restrictive, but it doesn’t have to be complicated. Remember my two rules: when you eat and what you eat. Choose my favorite foods—that bowl of broccoli, some turkey, a nice steak or pork chop. Time your meals strategically around your brushing routine.
Think about those bacteria waiting patiently on your teeth for their next carbohydrate meal. Give them broccoli instead of bread. Don’t let them cross that enamel barrier—because once they do, you’re looking at fillings, crowns, and a lot more expensive dental work.
We don’t want them to cross that barrier. Keep that hard candy shell strong, and your teeth will thank you for it. Trust me, after seeing thousands of cavities that could have been prevented, I know what works.
