Small intestinal histologyAkkermansia muciniphila is a fascinating bacterial inhabitant of the human gastrointestinal (GI) tract, identified in 2004 by a Dutch research group. Akkermansia, the only member of the broad class of the Verrucomicrobia phylum in the human microbiome, can provide considerable health advantages to its human host. But it can also turn against you and create serious health problems. So getting Akkermansia right can be an important facet of health.

People who are overweight, obese, or have type 2 diabetes have reduced numbers of Akkermansia in their GI microbiomes, as do people with inflammatory bowel diseases (ulcerative colitis, Crohn’s disease). Preliminary evidence suggests that increasing Akkermansia populations in the intestinal microbiome may thereby reduce blood sugar, HbA1c, and insulin resistance, and may be part of the solution for inflammatory bowel diseases and other conditions.

On the positive side, Akkermansia has been shown to:

  • Increase intestinal mucus production–Mucus is the slimy material that separates microbes and foods undergoing digestion, as well as stomach acid and bile, from the intestinal wall. It is also lubricant and a medium for the intestinal immune response. Having plentiful and constantly renewed mucus is a health advantage.
  • Produce metabolic mediators such as butyrate that, upon absorption into the bloodstream, generate beneficial effects such as reducing insulin resistance, reducing blood sugar and blood pressure. In other words, having healthy quantities of Akkermansia provides metabolic health advantages.
  • Reduce endotoxemia—i.e., reduces the entry of bacterial breakdown products (lipopolysaccharide, lipoteichoic acid others) into the bloodstream, adding to effects such as reduced insulin resistance and reduced blood sugar and blood pressure. A reduction in endotoxemia exerts numerous other health effects such as reduced potential for depression, anxiety, and inflammation.
  • Secrete antibacterial peptides—and thereby inhibiting potentially pathogenic bacterial species in the vicinity.
  • Help digest human milk oligosaccharides (HMOs) by infants feeding on breastmilk. Bifidobacteria are the main HMO digesters in the infant GI tract, but Akkermansia also plays a role.

It all depends on diet and the relative quantity of Akkermansia. In the normal or healthy situation, Akkermansia occupies 3-5% of all microbes in the GI tract, conferring its considerable benefits. Akkermansia loves prebiotic fibers such as inulin/fructooligosaccharides (FOS) and increases in numbers when such fibers are supplied through diet. Akkermansia also responds well to the oleic acid of dietary oils such as extra-virgin olive oil, to polyphenols in vegetables and fruits, and to intermittent fasting. Include inulin/FOS sources such as onions, garlic, shallots, green unripe bananas, or commercial powder sources, along with extra-virgin olive oil and polyphenol-rich foods, and enjoy extended periods of not eating, and you should have a healthy level of Akkermansia supporting your intestinal and metabolic health.

But Akkermansia has Jekyll-and-Hyde capacity. As its name suggests—“muciniphila” or mucus lover—when deprived of prebiotic fibers, Akkermansia has a distinct survival advantage: it can survive on human intestinal mucus. Most other microbial species in the human GI tract do not have this added capability and will be reduced in numbers or disappear with lack of prebiotic fibers and polysaccharides in the diet. The lack of competition therefore allows Akkermansia to proliferate unchecked and come to dominate, comprising 18%, 20%, even 24% of all microbes in the GI tract. This is not good, given Akkermansia’s appetite for human mucus. Overgrowth of Akkermansia has been shown to thin the mucus barrier and cause inflammation of the intestinal wall, as depicted in this illustration:

From Desai 2017

The deterioration of the mucus barrier has serious implications for health including intestinal inflammation/colitis experienced as conditions such as ulcerative colitis and diverticular disease, increased entry of bacterial breakdown products into the bloodstream (“endotoxemia”), and colon cancer.

Lack of prebiotic fibers and polysaccharides introduces other intestinal microbiome changes including:

  • Loss of diversity—Microbial diversity, i.e., having a large number of varied species, is a marker for intestinal health. The numbers of different species drops with deprivation of prebiotic fibers and polysaccharides, just as it does after a course of antibiotics.
  • Loss of Bifidobacteria species—These are species that provide beneficial effects to human hosts
  • Increase in Proteobacteria—These are the species of dysbiosis and small intestinal bacterial overgrowth,SIBO, species such as E. coli, Citrobacter, and Klebsiella.
  • Increase in Fusobacterium—This is especially concerning, as this microbe has been associated with colon cancer.

In short, obtain plenty of prebiotic fibers and polysaccharides from root vegetables, onions, garlic, legumes, etc. and Akkermansia provides intestinal health and metabolic advantages. Fail to take in such nutrients and Akkermansia can overproliferate, dominate the intestinal microbiome, and lead to substantial health problems.