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

## TL;DR

This study explores how diet quality, especially added sugar, affects the oral microbiome in over 5,000 people across three US studies.

## Contribution

The study identifies added sugar as a key dietary factor influencing oral microbial diversity and specific genera.

## Key findings

- Age and smoking were the main factors affecting oral microbiome beta diversity.
- Added sugar consumption was consistently linked to lower alpha diversity and specific genus-level changes.
- Overall diet quality did not significantly affect alpha diversity, but specific components like added sugar did.

## Abstract

The oral microbiome has been associated with overall health, but the contribution of dietary habits to oral microbial composition is not well understood.

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.

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.

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.

Consumption of added sugars was consistently associated with oral microbial diversity and specific genera.