Association between serum antibodies to oral microorganisms and nonalcoholic fatty liver disease in adults

Alterations in the bacteria, such as the periodontal bacteria, might be considered potential risk factors for nonalcoholic fatty liver disease (NAFLD). Most studies analyzing this association have focused mainly on a specific periodontal bacteria (Porphyromonas gingivalis) and have involved relatively small study populations (tens or hundreds of individuals). To address this gap, a sizable, nationally representative adult population was utilized to investigate the association between the incidence of NAFLD and high serum IgG antibodies for 19 periodontal bacteria. To explore this association, data from the Third National Health and Nutrition Examination Survey (NHANES III)—which provides a cross-sectional representation of the noninstitutionalized U.S. population, encompassing 33,994 individuals—were analyzed. Participants aged 40 years and above with data on NAFLD—determined by the gold standard of ultrasound examination (USON)—as well as comprehensive records of serum IgG antibodies against periodontal bacteria, were included, resulting in a final analysis subset of 6,330 individuals. Using a cluster analysis based on the Socransky classification scheme for oral microorganisms, antibody titers for the 19 bacteria were grouped into four clusters—Red-Green, Orange-Blue, Yellow-Orange, and Orange-Red. When these clusters, as well as individual antibody relationships with NAFLD, were examined, the adjusted odds ratios (ORs) ranged from 0.958 [95% confidence interval (CI): 0.916, 1.003] to 1.021 [95% CI: 0.987, 1.055]. This indicated that no statistically significant associations were found (P > 0.05), underscoring the absence of a meaningful link. In summary, it was discovered that there is currently no evidence to correlate serum antibodies to periodontal pathogens with NAFLD in the nationally representative NHANES III. Not applicable.