# Association between a novel Dietary Index for Gut Microbiota and periodontitis: a cross-sectional study

## TL;DR

A new dietary index for gut microbiota is linked to lower odds of periodontitis, with body mass index playing a mediating role.

## Contribution

Introduces the Dietary Index for Gut Microbiota (DI-GM) and its association with periodontitis.

## Key findings

- Higher DI-GM scores were inversely associated with periodontitis (OR = 0.94).
- BMI significantly mediated the relationship between DI-GM and periodontitis.
- The association remained significant for moderate and severe periodontitis after adjustment.

## Abstract

The gut microbiota and periodontitis have attracted increasing research interest. The Dietary Index for Gut Microbiota (DI-GM), a novel metric for assessing gut microbiome diversity, has not yet been investigated in relation to periodontitis.

This cross-sectional study analyzed data from the 2009–2014 National Health and Nutrition Examination Survey including 9,978 participants aged 30–80 years who had periodontal examination records. Participants were categorized into two groups: no periodontitis (n = 4,879) and periodontitis (mild, moderate, or severe; n = 5,099). The DI-GM was calculated using dietary recall data, incorporating both beneficial and unfavorable components for gut microbiota. Multivariable logistic regression was applied to examine the association between DI-GM and periodontitis, with body mass index (BMI) evaluated as a potential mediator. Secondary analyses included subgroup evaluations, restricted cubic spline (RCS) modeling, and multivariable imputation.

A higher DI-GM score was inversely associated with periodontitis (odd ratio [OR] = 0.94, 95% confidence interval [CI]: 0.91–0.97). Similarly, a higher beneficial microbiota score was linked to a lower prevalence of periodontitis (OR = 0.90, 95% CI: 0.87–0.94). After adjustment, DI-GM remained inversely associated with moderate (OR = 0.94, 95% CI: 0.91–0.97) and severe periodontitis (OR = 0.89, 95% CI: 0.85–0.94; both p < 0.001). Likewise, higher beneficial microbiota scores correlated with reduced odds of moderate (OR = 0.91, 95% CI: 0.87–0.95) and severe periodontitis (OR = 0.84, 95% CI: 0.79–0.90; all p < 0.001). The RCS model indicated a linear association between DI-GM and periodontitis. BMI showed a significant mediating effect (4.9, 95% CI: 0.96–11.05%; p = 0.014).

The newly proposed DI-GM demonstrated an inverse association with the prevalence of periodontitis, with BMI acting as a significant mediator in this relationship.