Taters and toast could be tooth trouble in disguise.
A new study suggests that the number of AMY1 gene copies you have plays a crucial role in how the bacteria in your mouth respond to starch, potentially increasing the risk of cavities and gum disease for some people.
“Most people have been warned that if you eat a bunch of sugar, make sure you brush your teeth,” said Angela Poole, senior author and assistant professor of molecular nutrition at Cornell University. “The takeaway finding here is that depending on your AMY1 copy number, you may want to be just as vigilant about brushing your teeth after eating those digestible starches.”
The AMY1 gene is responsible for producing salivary amylase, an enzyme that helps digest starch in the mouth.
Earlier studies have linked AMY1 to cavities and periodontal disease. However, scientists haven’t fully understood how salivary amylase interacts with starch to disrupt the oral microbiome and increase the odds of dental disaster.
“That’s what we wanted to know in this experiment. What’s going on in the mouth if someone eats starch, and is the answer different if their copy number is high or it’s low?” Poole said. “What we found was that there are other bacteria involved in these processes and that the changes depended on AMY1.”
For the study, researchers collected saliva samples from 31 adults, each with different AMY1 copy numbers. They then added starch to the cultured samples, or biofilms, and observed how the bacterial makeup shifted.
In samples with high AMY1 numbers, the team found that starch significantly reduced the proportions of two bacteria — Atopobium and Veillonella — while Streptococcus levels increased. All three bacteria are associated with tooth decay or gum disease, according to Poole.
“Some increased and some decreased, so it’s not so straightforward as saying, ‘The whole thing is good or bad,’” Poole said. “It’s an interaction, but it looks like the AMY1 copy number, as well as which species are present in people’s mouths when they eat starch, is affecting the risk for developing these diseases.”
The study findings don’t mean you should ditch starch from your diet.
For most people, starchy foods are a important source of carbohydrates and play a vital role in a balanced diet when eaten in moderation. They provide energy and fiber, along with essential vitamins and minerals.
Starch-rich foods include bread, cereals, pasta, rice, potatoes, beans, corn and even bananas. People with higher AMY1 copies have an easier time breaking down starchy foods — a genetic variation that researchers believe evolved in certain groups over time.
“The populations that historically had greater access to starch tend to have more copies,” Poole said, “which makes sense from a practical standpoint, because it would have given you a survival advantage when food is scarce, to be able to break down those starches more efficiently.”
While this may have its benefits, Poole said the study also points to potential downsides for your teeth and gums. “If someone has a high copy number, they break down starch efficiently, and bacteria that like those sugars are going to grow more in that person’s mouth,” she noted.
The research could open the door to more personalized dental care. By understanding your genetic makeup, dentists might one day offer recommendations tailored to your individual risks when it comes to starch metabolism and oral bacteria.
The result? A happier mouth and a healthier you. After all, tooth decay and gum disease don’t just mess with your smile or make eating and talking a challenge — they can affect your entire well-being.
Poor oral health has been linked to a range of serious conditions, including heart disease, diabetes, Alzheimer’s and certain cancers. Experts believe the issue lies with bacteria from the mouth entering the bloodstream, triggering inflammation that spreads throughout the body.
Dental and mental health are closely connected as well. Struggling with issues like gum disease or tooth decay can trigger feelings of embarrassment, low self-esteem, and anxiety, often leading to social isolation and a decline in overall quality of life.
