Gut bacteria Akkermansia is associated with reduced risk of obesity: evidence from the American Gut Project

BACKGROUND: Gut bacteria Akkermansia has been shown an anti-obesity protective effect in previous studies and may be used as promising probiotics. However, the above effect may be confounded by common factors, such as sex, age and diets, which should be verified in a generalized population. METHODS: We used datasets from the American Gut Project to strictly reassess the association and further examined the effect of aging on it. A total of 10,534 participants aged 20 to 99 years from the United States and the United Kingdom were included. The relative abundance of Akkermansia was assessed based on 16S rRNA sequencing data. Obesity (body mass index, BMI ≥ 30 kg/m(2)) risks were compared across Akkermansia quintiles in logistic models with adjustment for common confounders. Restricted cubic splines were used to examine dose response effects between Akkermansia, obesity and age. A sliding-windows-based algorithm was used to investigate the effect of aging on Akkermansia-obesity associations. RESULTS: The median abundance of Akkermansia was 0.08% (interquartile range: 0.006–0.93%), and the prevalence of obesity was 11.03%. Nonlinear association was detected between Akkermansia and obesity risk (P = 0.01). The odds ratios (95% confidence interval) for obesity across the increasing Akkermansia quintiles (referencing to the first quintile) were 1.14 (0.94–1.39), 0.94 (0.77–1.15), 0.70 (0.56–0.85) and 0.79 (0.64–0.96) after adjusting for age and sex (P for trend < 0.001). This association remained unchanged after further controlling for smoking, alcohol drinking, diet, and country. The odds ratios (95% CI) of Akkermansia were 0.19 (0.03–0.62) and 0.77 (0.64–0.91) before and over 40 years, respectively, indicating that the protective effect of Akkermansia against obesity was not stable with aging. CONCLUSION: High relative abundance of Akkermansia is associated with low risk of obesity and the association declines with aging.