Think only sugar causes cavities? These foods might just be bad for your teeth

Brushing your teeth after eating starchy foods might be more important for some people than others, thanks to a fascinating new study from Cornell University. Picture this: Your genetics might be secretly influencing the bacteria in your mouth and could be the reason you get more cavities or gum issues—even if you’re diligent about brushing.

Led by Angela Poole at Cornell's Division of Nutritional Sciences, this study uncovered how variations in the AMY1 gene, which helps break down starch, can impact your mouth's bacterial squad. That means, depending on your genes, some of you might need to step up your tooth-brushing game after indulging in certain snacks.

The starch connection: Why It’s about more than just sugar

The AMY1 gene is responsible for creating salivary amylase, the enzyme that gets the ball rolling when you eat starchy foods. But here’s the twist: People with more copies of the AMY1 gene produce more of this enzyme, allowing them to break down starches more efficiently. So, if you’ve got a lot of AMY1 copies, your mouth may be extra busy processing those starchy carbs, making it even more important to brush right after.

Dr. Poole, the study’s senior author, explained it this way: Most people know they should brush their teeth after eating sugary foods. But depending on your AMY1 copy number, you might want to brush just as thoroughly after munching on starchy foods too.

What does your AMY1 copy number mean for your teeth?

Here’s where it gets interesting. Some people have as few as 2 copies of the AMY1 gene, while others might have as many as 20. Those with more copies of the gene produce more salivary amylase, which helps break down starchy foods better. This trait evolved long ago when humans shifted to agricultural diets, and starchy foods became a major part of our meals.

The Cornell team grew bacteria from the saliva of 31 volunteers with different AMY1 copy numbers and discovered a few things. When starch was present, bacteria from people with higher AMY1 copies behaved differently than those with fewer copies. Specifically, two types of bacteria—Veillonella and Atopobium—which are linked to cavities and gum disease, were less abundant in those with higher AMY1 copy numbers. “If you’ve got more copies, your body breaks down starch faster, and that can create an environment where certain bacteria thrive,” said Poole. In other words, your genetics are shaping the types of bacteria that call your mouth home.

How can you tell if you have more AMY1 copies?

If starchy foods taste extra sweet to you as soon as you start chewing, it could mean your amylase is working overtime, possibly due to more AMY1 copies.

Some specialised genetic tests can measure your AMY1 copy number, though these are not usually included in standard consumer DNA kits. You could ask a healthcare provider about a salivary amylase activity test, which measures how much of the enzyme is active in your saliva, and correlates with your AMY1 copy number.

So, what should you do?

Even though you probably won’t be running out to get genetic testing just for dental reasons, it’s still a good idea to pay attention to how your teeth respond to starchy foods. And here’s the key takeaway: no matter your genetic makeup, brushing your teeth after eating starchy foods, especially processed ones, is always a good move.