Oral microbiome and obesity in a large study of low-income and African-American populations

Few studies have evaluated the relationship of oral microbiome with obesity. We investigated the oral microbiome among 647 obese and 969 non-obese individuals from the Southern Community Cohort Study, through 16S rRNA gene sequencing in mouth rinse samples. We first investigated 16 taxa in two probiotic genera, Bifidobacterium and Lactobacillus. Among them, eight showed nominal associations with obesity (P < 0.05). Especially, Bifidobacterium (odds ratio [OR] = 0.67, 95% confidence interval [CI]:0.54, 0.83) and Bifidobacterium longum (OR = 0.57, 95% CI: 0.45, 0.73) were significantly associated with decreased obesity prevalence with false-discovery rate (FDR)-corrected P of 0.01 and 5.41 × 10^-4, respectively. Multiple other bacterial taxa were also significantly associated with obesity prevalence at FDR-corrected P < 0.05. Among them, five in Firmicutes and two respectively in Actinobacteria and Proteobacteria were significantly associated with increased obesity prevalence. Significant associations with decreased obesity prevalence were observed for two taxa respectively in Actinobacteria and Firmicutes. Most of these taxa were associated with body mass index at study enrollment and weight gain during adulthood. Also, most of these associations were observed in both European- and African-Americans. Our findings indicate that multiple oral bacterial taxa, including several probiotic taxa, were significantly associated with obesity.