Akkermansia Side Effects: What the Human Trials Show

Akkermansia side effects in published human trials have been mild and mostly digestive, such as gas, bloating, abdominal discomfort or a change in bowel habits, and no serious side effect has been tied to Akkermansia in those studies. In most trials that tracked them, these complaints were no more common than with placebo, although one 2026 trial of 142 adults recorded somewhat more digestive complaints in the Akkermansia group. Here is what each study found, how live and pasteurized forms differ, who should check with a physician first, and how our capsule compares with what was tested.

Akkermansia side effects: what the human trials report

The human research is still small: a handful of controlled trials lasting 12 weeks to six months, most of them using pasteurized cells (heated so they are no longer alive) rather than live ones. Within that limit, the safety picture has been steady.

The first full trial was published in 2019. Researchers in Belgium gave 40 adults with overweight or obesity and insulin resistance a placebo, 10 billion live Akkermansia cells, or 10 billion pasteurized cells every day for three months, and 32 finished. Blood tests of liver function, kidney function, blood counts and clotting were checked at two weeks and at three months, and every two weeks participants reported any nausea, gas, bloating, cramps, gut rumbling or reflux. The researchers reported no adverse events in their safety review, and the self-reported digestive complaints were uncommon in every group, with none differing significantly from placebo. At the two-week check, bloating was reported by 2 of 13 people on placebo, none of 13 on pasteurized cells and 1 of 14 on live cells.

An earlier report from the same team, published in 2017, gave 5 volunteers per group live cells at 1 billion or 10 billion a day, or pasteurized cells at 10 billion a day, for 15 days. It found no changes in safety measures and no reported adverse events.

A 2026 trial in Ireland and Germany gave 142 adults with metabolic syndrome either 30 billion pasteurized cells (strain MucT) or a placebo every day for four months. Most adverse events were mild or moderate. Digestive complaints, including indigestion, abdominal discomfort, gas and altered bowel movements, were reported by 36 percent of the Akkermansia group and 24 percent of the placebo group, although the authors found no statistical difference between groups for any of the most common adverse events. Two people stopped the supplement, one for mild abdominal discomfort and one for moderate leg swelling, and the only serious adverse event, a pneumonia, occurred in the placebo group. Several of the authors work for the company that makes this ingredient.

Three other trials point the same way. A 2026 weight maintenance trial of 90 adults in the Netherlands found no serious adverse events related to the supplement, and a 2024 trial of 100 adults aged 60 and older in Korea found no notable safety concerns; both used pasteurized cells. A 2020 trial in the United States of 76 adults with type 2 diabetes tested a formula of live Akkermansia, four other organisms and inulin fiber; digestive symptoms were reported by 15 percent on that formula and 27 percent on placebo, though with several ingredients the result cannot be pinned on Akkermansia alone.

Akkermansia muciniphila side effects, study by study

So far, no trial has tied Akkermansia to a serious side effect, and the most common complaints were digestive and mild or moderate. The trials were small, though, and the longest gave the supplement for about six months.

Can Akkermansia cause bloating or gas?

It can. In the 2019 trial, gas and bloating stayed uncommon in every group, including placebo. In the 2026 trial, digestive complaints were more frequent with Akkermansia, though mild or moderate, and only one person stopped because of abdominal discomfort.

That pattern is familiar from probiotics in general: a few days of extra gas, bloating or a change in stool as the gut adjusts, which usually settles within the first week or so. Taking the capsule with food, as our label directs, and staying at one capsule a day for the first weeks are sensible first steps. If symptoms do not settle within the first week or two, stop and check with your physician.

Is Akkermansia safe? Live versus pasteurized

The most formal safety review is European. In 2021 the European Food Safety Authority assessed pasteurized Akkermansia as a novel food and concluded that 34 billion cells a day is safe for adults, excluding pregnant and breastfeeding women. That conclusion rested mainly on a 90-day toxicity study in rats, with a 200-fold safety margin applied, and it covers only pasteurized cells with no detectable live bacteria. A 2025 update extended it to adolescents from age 12 and stated that safety in pregnancy and breastfeeding has not been established.

Live Akkermansia, the form in our capsule, has a smaller human safety record: the live groups in the 2017 report and the 2019 trial, plus the multi-strain formula above. Those studies did not raise safety concerns, but they add up to fewer people over shorter periods than the pasteurized research. That is one reason the physician-check list below matters, especially for anyone with a weakened immune system, since a live organism is different from an inactivated one.

Does Akkermansia damage the gut lining?

It is a fair question, because Akkermansia feeds on mucin, the main component of the mucus layer lining the gut. The worry traces back to a 2016 study in mice colonized with 14 human gut bacteria. When the mice were fed a diet with no fiber, mucus-feeding species, including Akkermansia, expanded, the colon mucus layer thinned, and the mice became more vulnerable to a gut infection. The driver in that study was fiber deprivation acting on the whole bacterial community, not Akkermansia alone.

Other mouse work points the other way. In a 2013 study, a high-fat diet left mice with a mucus layer 46 percent thinner, and daily live Akkermansia for four weeks reversed that loss. No human trial I found has reported damage to the gut lining from Akkermansia supplements, and in the 2019 trial, pasteurized cells lowered a blood marker of bacterial products leaking from the gut compared with placebo. The practical point holds either way: eat a varied, fiber-rich diet so the bacteria in your gut have plant fiber to work with.

How our capsule compares with what was studied

Our Akkermansia Probiotic contains Akkermansia muciniphila, 1 billion AFU per capsule, as a live, microencapsulated strain. The label directs one capsule daily with food, up to two a day. Compared with the trials:

• Form. Ours is live. Most safety trials, and the European safety review, used pasteurized cells.
• Amount. Most trials used 10 billion to 30 billion cells a day; the closest match to our count is the 2017 safety check, which included live cells at 1 billion a day for 15 days. AFU and cell counts come from different measurement methods, so the numbers line up only roughly, but our capsule sits at the low end of what has been given to people.
• Preparation. Each study used its own strain and preparation, and none tested our capsule, so those results are background, not proof of how our capsule behaves.

For more on units and amounts, see our guide to Akkermansia dosage and what AFU means.

Who should check with a physician first

Talk to your physician before taking Akkermansia if you:

• Are pregnant or breastfeeding. European regulators have stated that its safety in pregnancy and breastfeeding has not been established.
• Have a weakened immune system, take immunosuppressive medication or chemotherapy, have a central venous catheter, or are seriously ill. A live organism calls for extra caution in these situations.
• Are considering it for a child.
• Take prescription medication, or have a digestive condition or another ongoing health condition.

Stop and contact your physician if digestive symptoms do not settle within the first week or two. Seek care promptly for severe abdominal pain, blood in your stool, or a fever, especially if your immune system is weakened.

How Vita Bloom fits

Our Akkermansia probiotic provides Akkermansia muciniphila, 1 billion AFU, in a vegetable cellulose capsule with microcrystalline cellulose and magnesium stearate (less than 2%, vegetable source). It is shelf-stable at room temperature, with no refrigeration needed, and is made in a GMP-certified facility and third-party tested. Take one capsule daily with food, up to two a day, and give it at least 4 to 8 weeks of consistent use before judging results. It supports the gut lining and a balanced gut.* For what the research does and does not show on the upside, see our guide to Akkermansia benefits.

Frequently asked questions

What are the most common Akkermansia side effects?

In human trials, the reported side effects were mild and mostly digestive: gas, bloating, abdominal discomfort, indigestion or a change in bowel habits. No serious side effect was tied to Akkermansia in those studies.

Is Akkermansia safe to take every day?

Daily use for 12 weeks to six months was well tolerated in the published trials, and European regulators judged pasteurized Akkermansia safe for adults at up to 34 billion cells a day. Longer-term data are limited, and live forms have a smaller safety record.

Are Akkermansia probiotic side effects different for live and pasteurized forms?

No study has shown a clear difference. The 2019 trial gave both forms at the same daily amount and observed no adverse events with either. Most safety data, including the European review, come from pasteurized cells, so live forms have a smaller record.

Who should not take Akkermansia without a physician?

Anyone pregnant, breastfeeding, immunocompromised, seriously ill, on prescription medication or managing a digestive condition, and any child.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.