Starch and Cavities: The Genetic Link

• Eating starch can lead to cavities in individuals with high AMY1 gene copy numbers.
• AMY1 codes for amylase, an enzyme that breaks down starch, affecting oral bacteria levels.
• Researchers suggest vigilance in dental hygiene after consuming starchy foods.
• AMY1 copy number testing is not widely accessible, making preventive care essential.

---

The Role of AMY1 in Oral Health

A recent study conducted by researchers at Cornell University has uncovered a connection between the AMY1 gene, starch consumption, and dental health. The AMY1 gene produces salivary amylase, an enzyme responsible for breaking down starch into simpler sugars. According to findings published on Newsweek, variations in the number of AMY1 copies a person carries can influence their susceptibility to cavities and other oral diseases.

“Most people have been warned that if you eat a bunch of sugar, make sure you brush your teeth,” said Angela Poole, a molecular nutrition professor and co-author of the study, in a statement. “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.”

Starch, found in foods like bread, pasta, and baked goods, can contribute to tooth decay when broken down into sugars by salivary amylase. This process creates an environment where certain bacteria thrive, increasing the risk of cavities.

---

How AMY1 Copy Numbers Influence Bacterial Growth

The study, which analyzed saliva samples from 31 participants in Ithaca, New York, revealed significant differences in oral microbiomes based on AMY1 copy numbers. Participants had between two and 20 copies of the gene, and those with higher numbers showed elevated levels of Streptococcus bacteria, which feed on the sugars produced during starch digestion.

“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,” explained Poole. Conversely, bacteria such as Atopobium and Veillonella were less abundant in individuals with higher AMY1 copy numbers.

“So you can have species behave differently based on the different substrates. It’s pretty incredible how we adapt and these microbes turn around and adapt, too,” she added.

This interplay suggests that the oral microbiome has coevolved alongside increases in AMY1 gene copies over time, particularly in populations with long histories of agriculture.

---

Historical Context and Evolutionary Implications

The research also highlights an evolutionary aspect of the AMY1 gene. Populations with historical access to starchy foods tend to have more copies of the gene, likely because it provided a survival advantage during periods of food scarcity.

“The populations that historically had greater access to starch tend to have more copies,” Poole noted. “This 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 adaptation may have been beneficial in ancient times, it now poses challenges for modern dental health, especially given the prevalence of processed starchy foods in contemporary diets.

---

Practical Considerations and Future Research

Despite the insights gained from the study, determining one’s AMY1 copy number remains inaccessible for most people. “Determining AMY1 copy number requires lab equipment and reagents. It’s not usually an at-home in the basement activity,” Poole explained.

She further stated, “I doubt that genealogy companies will genotype AMY1 because they’re probably focused on single nucleotide polymorphisms.” As a result, maintaining good oral hygiene practices remains the most practical approach to mitigating risks associated with starch consumption.

Looking ahead, Poole plans to expand her research by studying larger groups under varying conditions and exploring how these dynamics unfold over different timescales.

---

Conclusion

The Cornell University study sheds light on the complex relationship between genetics, diet, and oral health. While starch consumption has long been linked to cavities, this research underscores the importance of individual genetic factors in determining susceptibility. For now, experts recommend treating starchy foods with the same caution as sugary ones—brushing regularly and staying informed about emerging science.

Reference: Superdock, D. K., et al. (2025). The Impact of Human Salivary Amylase Gene Copy Number and Starch on Oral Biofilms. Microorganisms, 13(2). https://doi.org/10.3390/microorganisms13020461