Association between diet quality and the oral microbiome in three US cohort studies

Background: The oral microbiome has been associated with overall health, but the contribution of dietary habits to oral microbial composition is not well understood. Objective: We evaluated the association between diet quality (Healthy Eating Index [HEI] 2015) and the oral microbiome in the Agricultural Health Study, NIH-AARP Diet and Health Study, and Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial within 5,546 participants. Methods: Individual HEI components were scored from FFQ data and summed. Alpha and beta diversity and genus-level presence and relative abundance were estimated. The proportion of variability in the beta diversity matrices explained by diet quality and other covariates were calculated. Linear, logistic, and zero-inflated negative binomial regression models with adjustment for confounders were used and cohort-specific estimates were meta-analyzed. Results: Age explained the largest variability in beta diversity (Bray-Curtis), followed by smoking, education, and the HEI component for added sugar. Although overall diet quality was not associated with alpha diversity overall, the added sugar component was consistently inversely associated with alpha diversity. At the genus-level, most of the identified associations were with added sugar. Conclusions: Consumption of added sugars was consistently associated with oral microbial diversity and specific genera.