Starch can impact your oral health - depending on your DNA

Starch can impact your oral health - depending on your DNA

New research shows that your genetic makeup influences how starch shapes your oral microbiome and influences your risk of cavities and gum disease.

It's well known that sugar causes cavities, but research at the new Cornell University is examining how genetic variation in AMY1, a gene involved in starch digestion, influences the composition of oral bacteria, which can have implications for dental health.

The study found that starch reduces bacterial diversity in oral biofilms, meaning certain bacteria thrive while others decline, potentially affecting the risk of cavities and gum disease.

The study published in the journalmicroorganismsexamines the response of the oral microbiome to starch. It finds that the number of copies of a particular gene, AMY1, combined with starch changes the complex composition of bacteria that play a role in oral health.

"Most people have been warned that if you eat a lot of sugar, brush your teeth," said Angela Poole, senior author and assistant professor of molecular nutrition. "The takeaway here is that depending on your Amy1 copy number, you may want to be just as vigilant about brushing your teeth after eating these digestible starches."

AMY1 codes for the salivary amylase enzyme, which breaks down starch in the mouth. Previous studies have linked AMY1 to cavities and periodontal disease. In previous studies, Poole found that high AMY1 copy number is associated with higher species Porphyromonas Endodontalis, which is associated with periodontitis. This study further investigates how starch affects the bacterial composition in the mouth, particularly the effects of Veillonella and Atopobium.

However, it was unclear how the salivary amylase enzyme interacts with its main substrate, starch, to alter the oral microbiome and increase the risk of disease.

“That’s what we wanted to know in this experiment,” Poole said. "What's going on in the mouth when someone eats starch, and does the response differ when their copy number is high or when it's low? What we found was that Veillonella and Atopobium responded differently depending on Amy1 copy number as well as the strength of the starch, suggesting that certain bacteria may be more influenced by genetic variations in the strength of the starch."

The researchers also found evidence that the oral microbiome has co-evolved in response to increasing copies of AMY1, which is found in higher numbers in populations where there is a long history of agriculture and starch consumption. In the pool of 31 samples collected in Ithaca, NY, the Amy1 number ranged from two to 20 copies.

Unlike sugars, which quickly drive bacterial growth, starch interacts with Amy1 to gradually shape the oral microbiome, influencing which bacteria dominate over time.

"The populations that have historically had greater access to starches 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 break down those starches more efficiently."

In onin vitroIn the study using cultured oral biofilms, researchers saw increased populations of bacteria such as Streptococcus in starch-supplemented biofilms, particularly in individuals with high AMY1 copy numbers. However, Veillonella and Atopobium showed the strongest changes in response to starch and AMY1 copy number, indicating a more complex relationship between these bacteria and starch metabolism.

"If someone has a high copy number, they will efficiently break down the starches and bacteria like these sugars will grow more in that person's mouth," Poole said. "Our results suggest that different species of bacteria behave differently depending on the carbohydrates available and an individual's genetic make-up. It's pretty incredible - how we adapt and these microbes pivot and adapt too."

The study also found that biofilms from individuals with periodontitis had lower bacterial diversity compared to patients from healthy individuals, which has implications for how starch metabolism over time influences the risk of oral disease. Furthermore, starch supplementation reduced microbial diversity in biofilms, possibly by favoring certain bacteria over others.

The Schwartz Research Fund and the National Institutes of Health received funding.

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