Introduction to Akkermansia muciniphila
Akkermansia muciniphila (Akkermansia) is a Gram-negative, anaerobic, non-spore-forming and oval-shaped bacterium. It is a member of the Verrucomicrobia phylum and is part of the human commensal bacterium.
It was isolated in 2004 and named after Dr. Antoon Akkermans, a dutch microbiologist. The word muciniphila is derived from the Latin and Greek words for mucin loving, where phila (philos) is loving.
Akkermansia is abundantly present in the healthy human intestinal tract, making up to 1-5% of the microbial community of the colon. 1 It is very important to human health that the population of Akkermansia is high and not depleted, since its abundance inversely correlates with body weight and type 1 diabetes in mice and humans.
Akkermansia plays a crucial role in the mutualism between the gut microbiota and host that controls gut barrier function and other physiological and homeostatic functions during the following conditions:
Akkermansia Colonizes the Mucus Layer of the Colon
The gastrointestinal tract is covered with a layer of mucus which serves, among other things, as a source of nutrients for bacterial growth. 5 This mucus layer attracts bacteria which colonize, survive and multiple inside and on the mucus layer. Akkermansia is the most abundant mucus degrading bacteria in the healthy individual.
Akkermansia muciniphila activity and interactions in the intestine. Schematic overview of the metabolic activities of A. muciniphila in the gut and the microbiota and host response as a result of A. muciniphila colonization. As a result of mucus degradation, A. muciniphila produces oligosaccharides and SCFAs. These products can stimulate microbiota interactions and host response. Oligosaccharides and acetate stimulate growth and metabolic activity of bacteria that colonize close to the mucus layer. This may provide colonization resistance to pathogenic bacteria that have to cross the mucus layer to reach the intestinal cells. The propionate produced by Akkermansia-like bacteria can signal to the host via the Gpr43 receptor and other SCFA may also do the same via Gpr41 (Le Poul et al., 2003; Maslowski et al., 2009). This may trigger a cascade of responses in the host expression machinery and together with other signaling pathways has shown to result in immune stimulation and metabolic signaling in monoassociated germ-free mice (Derrien et al., 2011). Source: Microbes inside—from diversity to function: the case of Akkermansia
Mucus production and thickness is important to a healthy gastrointestinal tract and Akkermansia is key in this process. The host and Akkermansia communicate continually and create a positive feedback loop in which Akkermansia degrades the mucus layer which stimulates new mucus production and the the production of new mucus stimulates growth of Akkermansia. This process assures that abundant amounts of Akkermansia maintain the integrity and shape of the mucus layer. 6
Low population levels of Akkermansia indicates a thin mucus layer. This results in a weakened gut barrier function and the ability of toxins to translocate into the bloodstream.
Akkermansia Produces Important Metabolites
As a result of the mucus degradation process, Akkermansia produces two very important short chain fatty acids: 7
These short chain fatty acids trigger a cascade of responses in the host resulting in immune stimulation and metabolic signaling. 8
Studies have indicated that Akkermansia has an anti-inflammatory role in two gastrointestinal conditions:
Increasing Akkermansia muciniphila
At the present moment (January 2017), there is no commercially available probiotic supplement that contains Akkermansia muciniphila. Instead, increasing Akkermansia muciniphila can be accomplished through the consumption of certain prebiotics and foods.
Increasing Akkermansia colonization of the colon can be promoted by the administration of prebiotic substrates, including:
- arabinoxylan 11
- inulin 12
- fructooligosaccharides (FOS) (oligofructose) (increased the abundance of Akkermansia muciniphila by ∼100-fold in mice) 13
Akkermansia can also be increased by consuming polyphenol-rich foods, including:
- pomegranate (attributed to ellagitannins and their metabolites) 14
- grape polyphenols (grape seed extract) (proanthocyanidin-rich extracts may increase mucus secretion, therefore creating a favorable environment for Akkermansia to thrive) 15 16
- cranberries 17
Certain foods and fats can increase the abundance of Akkermansia:
Navy beans have been shown to increase Akkermansia abundance. Fecal abundance of Akkermansia muciniphila, whose abundance is inversely related to the severity of the obese phenotype, was increased in the high fat + bean diet group versus high fat diet by 20-fold. 18
Mice fed fish oil compared to lard for 11 weeks confirmed the increase in Akkermansia and Lactobacillus in the cecal contents. 19
The first-line medication for type 2 diabetes, Metformin, has been shown to significantly increase the relative abundance of Akkermansia in HFD-Met mice. 20