Akkermansia muciniphila (WB-STR-0001)

What is Akkermansia muciniphila (WB-STR-0001)?

Akkermansia muciniphila was first isolated in 2004, at Wageningen University, from the faeces of a healthy adult, by growing bacteria on a medium where gastric mucin was the only source of carbon and nitrogen. The strain that came out of that experiment, MucT, is still the reference strain, and the name describes the organism: “muciniphila” means mucin-loving. It is a strictly anaerobic bacterium — oxygen kills it — which lives in the mucus layer that lines the gut wall, and it is not unusual: a 2008 study using a DNA probe found it made up more than 1 per cent of the bacterial cells in adult faeces. What made it famous is a correlation. People with overweight, obesity, untreated type 2 diabetes and high blood pressure tend to carry less of it, which is why it is now sold as a supplement. Three strain names matter for reading the evidence. MucT is the strain the EU has authorised, in heat-killed form. AKK-WST01 is the live strain in the 2025 diabetes trial. WB-STR-0001 is Pendulum’s live strain, sold in its Akkermansia capsules and its multi-strain products. The US National Center for Complementary and Integrative Health is explicit that probiotic effects are strain-specific: what one strain does cannot be assumed for another, even within the same species.

How it works

The organism feeds on mucin, the glycoprotein that makes up the protective mucus over the gut lining, and in animal studies its presence is associated with that layer being renewed and the barrier between the gut and the bloodstream holding up better. The most important mechanistic finding, though, cuts against the way the live product is sold. In a 2017 mouse study in Nature Medicine, pasteurising the bacterium did not destroy its effects — it enhanced them, reducing fat-mass gain, insulin resistance and abnormal blood lipids more than the live organism did. The same study identified a protein on the bacterium’s outer membrane, Amuc_1100, that binds an immune receptor called Toll-like receptor 2, survives the temperatures used for pasteurisation, improves the gut barrier and on its own reproduces part of the benefit. If the active ingredient is a structural component rather than a living population, a dead bacterium can work, and “live” stops being the feature it is marketed as. The first human trial fits that reading: the pasteurised form lowered the activity of DPP-IV, an enzyme that breaks down gut hormones, while the live form and placebo did not. What it did not do is raise GLP-1. For live strains specifically, the 2025 diabetes trial adds a second idea — that a supplement only takes hold, and only helps, in a gut that has little of the organism to begin with.

What the research actually shows

Evidence strength varies by what is being claimed, so each use is graded separately against the published criteria rather than averaged into one reassuring letter.

Effective dosage

The only dose tested in a published trial of A. muciniphila on its own is 10 billion bacteria a day, taken for three months, in both live and pasteurised form. For the heat-killed strain MucT, the European Food Safety Authority set a safe intake of 3.4 × 10¹⁰ cells a day for adults, derived from a 90-day rat study by applying a 200-fold safety margin; the applicant had proposed up to 5 × 10¹⁰. That figure is a safety ceiling, not an effective dose, and it applies to the pasteurised product only. There is no established dose for any live strain taken alone, and none for WB-STR-0001. The 2025 trial adds a practical point that no label can: whether a live strain does anything may depend on how much of it you already carry, which only a stool test can tell you.

Where products diverge from the research. The gap here is large and easy to miss. Pendulum’s single-strain capsule provides 100 million AFU of WB-STR-0001 a day — a hundredth of the 10 billion bacteria used in the first human trial. AFU, or active fluorescent units, are counted by staining cells and passing them through a flow cytometer; the classic probiotic count, CFU, counts cells that grow into colonies on a plate. The two methods measure different things, no label converts between them, and nobody has shown what 100 million AFU corresponds to in trial terms. Across brands, counts run from 100 million to hundreds of billions of AFU, which is less a range of doses than a range of counting conventions. The second gap is regulatory. The EU’s authorisation covers pasteurised MucT; a live product is not covered by it, however similar the name on the front.

Safety, side effects and interactions

A. muciniphila is a normal member of the human gut community, and EFSA describes the reference strain as well characterised, non-toxin-producing and avirulent. In the first human trial, both live and pasteurised forms were well tolerated at 10 billion a day for three months, with no difference in adverse events between groups. EFSA’s safety conclusion excludes pregnant and breastfeeding women, and there is no safety data in children. The general cautions for live probiotics apply with full force here. The National Center for Complementary and Integrative Health notes that the risk of harm is greater in people with severe illness or weakened immune systems, that products have been found to contain organisms not on the label, and that in September 2023 the FDA warned of severe and sometimes fatal infections in premature infants given probiotics. Two research associations are worth knowing without overstating: A. muciniphila has been found at higher levels in untreated multiple sclerosis — where, in laboratory tests, it provoked inflammatory responses from human immune cells — and a five-country analysis found it raised in Parkinson’s disease. Neither shows the bacterium causes either condition, but both are reasons for anyone with those diagnoses, or with inflammatory bowel disease or a compromised immune system, to take a supplement to their clinician rather than their basket.

None of this is medical advice. See the medical disclaimer for what that means before you act on anything here.