A new study found that a person’s genetic profile and startch intake together influence the composition of oral bacteria, potentially affecting the risk for dental diseases such as cavities and periodontal (gum) disease.
The research focused on the amylase gene (AMY1) , which controls the production of salivary amylase—an enzyme that begins starch digestion in the mouth. People carry between two and 20 copies of this gene; more copies result in greater amylase production..
To examine how AMY1 variation affects oral bacteria, investigators collected saliva from 31 adults with a wide range of AMY1 gene copies. Some participants had a history of gingivitis, gum recession, or periodontitis, while others had no known periodontal disease.
Saliva was used to grow oral biofilms—bacterial communities that form on teeth—in lab dishes. The biofilms were cultured in two types of media: one with added starch and one without. This approached enabled the researchers to assess how starch and AMY1 copy number interacted to influence bacterial composition and diversity.
Results showed that both AMY1 gene copy number and starch presence bacterial diversity. Starch reduced microbial diversity overall, especially in samples from donors with a history of gum disease.
The relative abundance of two bacterial genera, Veillonella and Atopobium—both linked to cavities and gum disease—varied based on AMY1 copy number and starch exposure. Their levels decreased with more AMY1 copies in starch-rich media, but increased in starch-free media.
The researchers also observed a trend in Streptococcus abundance. In starch-containing media, individuals with more AMY1 copies had higher levels of Streptococcus, a group of bacteria often associated with tooth decay.
Despite the changes, each donor’s microbial community remained relatively distinct. Individual identity accounted for more than half of the variability in biofilm composition, suggesting that personal microbiome profiles play a substantial role alongside genetics and diet.
Donor age and gum disease status also influenced the biofilms. Samples from those with periodontitis had significantly lower bacterial diversity than those from donors without periodontal disease.
Although the study used an in vitro model, the findings support the idea that genetic variation and diet may influence the oral microbiome and related disease risk.
The authors reported no conflicts of interest.
Source: MDPI