Association between the quality of plant-based diets and periodontitis in the U.S. general population

To investigate the relationship between plant-based diet indices (PDIs) and periodontitis and serum IgG antibodies against periodontopathogens in the U.S.

We analysed cross-sectional data on 5651 participants ≥40 years of age from the Third National Health and Nutrition Examination Survey. Food frequency questionnaire data were used to calculate the overall PDI, healthy plant-based diet index (hPDI), and unhealthy plant-based diet index (uPDI). Periodontitis was defined using a half-reduced Centers for Disease Control and Prevention and American Academy of Periodontology case definition. Serum antibodies against 19 periodontopathogens were used to classify the population into two subgroups using hierarchical clustering. Survey-weighted multivariable logistic regressions were applied to assess the associations of PDI/hPDI/uPDI z-scores with periodontitis and hierarchical clusters after adjusting for potential confounders.

A total of 2841 (50.3%) participants were defined as having moderate/severe periodontitis. The overall PDI z-score was not significantly associated with the clinical and bacterial markers of periodontitis. By considering the healthiness of plant foods, we observed an inverse association between hPDI z-score and periodontitis (odds ratio [OR] = 0.925, 95% confidence interval [CI]: 0.860-0.995). In contrast, higher uPDI z-score (adherence to unhealthful plant foods) might increase the risk of periodontitis (OR = 1.100; 95% CI: 1.043-1.161). Regarding antibodies against periodontopathogens, the participants in cluster 2 had higher periodontal antibodies than those in cluster 1. The hPDI z-score was positively associated with cluster 2 (OR = 1.192; 95% CI: 1.112-1.278). In contrast, an inverse association between uPDI z-score and cluster 2 was found (OR = 0.834; 95% CI: 0.775-0.896).

Plant-based diets were associated with periodontitis, depending on their quality. A healthy plant-based diet was inversely related to an increased risk of periodontitis but positively related to elevated antibody levels against periodontopathogens. For an unhealthy plant-based diet, the opposite trends were observed.