Low Prevalence and Abundance of Akkermansia in Older Japanese Adults: Inverse Association with a Noodle-Based Dietary...

Akkermansia muciniphila is regarded as a beneficial mucin-degrading commensal, yet in Japanese populations the genus Akkermansia occurs at low abundance and is frequently undetectable. We examined its dietary correlates and its relationship with physical function in 786 community-dwelling older Japanese adults (age ≥ 65 years). Dietary patterns were derived from 31 food groups by principal component analysis (PCA) with varimax rotation, and Akkermansia was quantified by 16S rRNA gene sequencing and expressed as centered log-ratio (CLR)-transformed z-scores. Akkermansia was undetectable in 356 participants (45.3%) and of low abundance among carriers (median ≈ 0.35%). A noodle-based dietary pattern (principal component [PC] 4) was inversely associated with Akkermansia after adjustment for age, sex, body mass index, and lifestyle/comorbidity covariates (β = -0.125; p = 0.0007), with a dose-response across quartiles (p for trend = 0.004). In a two-part model, this association was confined to detection (adjusted odds ratio per 1 standard deviation = 0.80; 95% confidence interval, 0.69-0.93) and was absent among carriers (p = 0.25), indicating that diet was related to whether Akkermansia was present rather than to its abundance. Akkermansia was unrelated to grip strength, muscle mass, and frailty; weak carrier-restricted associations did not survive false discovery rate correction (p = 0.056) and are considered exploratory. These findings provide limited evidence for a role of Akkermansia in physical function in this low-abundance population.