Akkermansia muciniphila

Akkermansia muciniphila is a Gram-negative mucin-degrading bacterium that colonises the intestinal mucus layer and is typically present at <1 % to a few percent of the healthy gut microbiota, with substantial inter-individual variability. By continuously digesting mucin glycoproteins it stimulates host renewal of the mucus layer, thereby reinforcing the physical barrier between luminal contents and the epithelium. Lower abundance is associated with obesity, insulin resistance and inflammatory bowel disease in multiple cross-sectional cohorts, though causation is not established. Depommier et al. (Nat Med 2019) demonstrated in a randomised, double-blind, placebo-controlled proof-of-concept study that pasteurised — not live — A. muciniphila significantly improved insulin sensitivity and reduced insulinaemia in overweight adults, with a non-significant trend toward reduced body weight and fat mass; the pasteurised form consistently outperformed the live preparation in murine models as well, with the outer membrane protein Amuc_1100 (identified in mechanistic work by Plovier et al., Nat Med 2017) as a key mediator signalling through TLR2. The bacterium is now available as a novel food supplement in the EU, but clinical evidence remains limited to early-phase trials.