The protein, the receptor, the hormone: Akkermansia and GLP-1

You have heard of GLP-1 even if you do not know the acronym. It is the hormone at the centre of the largest conversation in metabolic medicine right now. What fewer people know is that your own gut makes GLP-1 naturally, and that Akkermansia muciniphila is one of the bacteria connected to that process. In 2021, researchers worked out exactly how.

What GLP-1 actually does

GLP-1, or glucagon-like peptide-1, is released by specialised cells in your intestinal wall called L-cells. It helps regulate blood sugar after meals, slows stomach emptying, and signals fullness to the brain. It is a normal, endogenous part of how your body handles food.

The 2021 discovery: a bacterial protein that triggers GLP-1

In 2021, Hyun Sik Yoon and colleagues went looking through the proteins that Akkermansia secretes, searching for one that might stimulate GLP-1 release. They found it: a single protein they named P9 (Yoon et al., 2021).

The mechanism is specific:

• Akkermansia secretes P9.
• P9 binds a receptor called ICAM-2 on the surface of intestinal L-cells.
• That binding triggers the L-cells to release GLP-1.

When the team gave P9 alone, with no bacterium at all, to obese mice, it increased circulating GLP-1, improved glucose tolerance, raised energy expenditure, and reduced weight gain. Remove the ICAM-2 receptor and the effect disappeared. A specific protein, a specific receptor, and an off-switch that works is about as clean as microbiome mechanism gets.

The finding appeared in Nature Microbiology. When people say "Akkermansia is the bug behind the GLP-1 conversation," they are pointing at this paper.

An important dose of honesty

P9 acts on your gut's own GLP-1 release. That is a nudge to a natural process, several orders of magnitude away from a prescription GLP-1 receptor agonist, and it should not be read as a substitute for one. This work is also in mice; the human evidence for Akkermansia and metabolism (Depommier et al., 2019) is still early. We describe rather than promise.

What can fairly be said is that Akkermansia sits at an active intersection of the gut, metabolism, and appetite, and that scientists are studying it there.

Why the berries belong here too

The mechanism also explains why we pair the bacterium with berries rather than selling it alone. The logic runs in one direction: berry polyphenols are linked in research to higher Akkermansia abundance (Henning et al., 2017 for pomegranate; similar findings for other berry polyphenols), more Akkermansia means more of the surface proteins and secreted factors such as Amuc_1100 (Plovier et al., 2017) and P9, and those are the molecules the research connects to metabolic effects. Vekovia · Bilberry is that pairing in one capsule, with the pasteurised bacterium, freeze-dried European bilberries and a standardised bilberry polyphenol extract.

Feeding the bacterium, in other words. For a food supplement, the reasoning behind that pairing is unusually well mapped.