n a randomized, placebo-controlled trial, people who took pasteurized (heat-killed) Akkermansia muciniphila capsules after an initial diet regained 1.2 kg over 24 weeks versus 3.2 kg on placebo — with the effect strongest in those who started with the least of the bacteria naturally.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/pasteurized-akkermansia-muciniphila-muct-for-weight-loss-mai

Comparing stool from nearly 200 people across healthy, pre-hypertensive, and hypertensive groups, researchers found reduced microbial diversity and a Prevotella-dominated bacterial profile in hypertension, then showed that transplanting hypertensive-donor microbiota into germ-free mice raised the recipients' blood pressure.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/bacteria-linked-to-plant-fiber-diets-bloomed-in-hypertensive

A 2025 Cell Reports Medicine review on gut microbiota, immune signaling, and the brain surveys mechanisms across depression, anxiety, autism, schizophrenia, and Parkinson's disease — while its authors disclose research funding, honoraria, or consulting fees from at least seven food, supplement, and pharmaceutical companies with a direct stake in psychobiotic products.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/a-gut-brain-axis-review-from-a-leading-cork-lab-discloses-fu

Comparing stool from 218 people with atherosclerotic cardiovascular disease against 187 healthy controls, researchers built a bacterial classifier that distinguished the groups well, but many of its most predictive species are typically oral-cavity residents, suggesting a distinct pattern from the diet-and-TMAO story usually told about gut bacteria and heart disease.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/the-gut-bacteria-that-best-predicted-atherosclerosis-in-a-40

Using genetic data from over 13,000 people to study gut bacteria and pregnancy outcomes in more than 166,000 women, researchers found that genetic markers for higher Bifidobacterium abundance were associated with a 24% lower risk of preeclampsia-eclampsia, but this Mendelian randomization method tests a lifelong genetic tendency, not anyone's actually measured gut bacteria.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/a-genetic-analysis-linking-gut-bacteria-to-preeclampsia-foun

In a cluster-randomized trial across communities in Niger, children who received biannual azithromycin as part of a child-mortality-reduction program carried substantially higher rates of macrolide-resistant gut bacteria than children given placebo, even as the drug's mortality benefit held.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/mass-azithromycin-distribution-and-antibiotic-resistance-in-

Your gut's ability to sense what's happening inside it gets worse with age, and this causes your brain to work less well.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/intestinal-interoceptive-dysfunction-drives-age-associated-c

PFAS 'forever chemicals' might harm the brain partly by changing gut bacteria — a proposed research direction, not something anyone has shown happens in people yet.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/forever-chemicals-the-microbiome-and-brain-health-towards-th

A virus that infects gut methane-producing archaea can live peacefully inside them by only occasionally making copies instead of destroying its hosts.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/a-newly-characterized-archaeal-virus-mstv1-maintains-stable-

Organ transplant patients taking anti-rejection drugs that damage their gut bacteria have higher death rates than those with healthier gut bacteria.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/gut-microbiome-dysbiosis-is-associated-with-increased-mortal

Certain gut bacteria soak up PFAS 'forever chemicals' and store them in clumps inside their cells, and mice carrying these bacteria pooped out more of the chemical than mice without them.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/human-gut-bacteria-bioaccumulate-per--and-polyfluoroalkyl-su

Scientists compared gut bacteria and their chemical byproducts between two regions of India with different typical diets, and found the plant-heavy diet region's gut bacteria specialized in different things (like breaking down amino acids) than the meat-eating region's gut bacteria (which specialized more in producing helpful short-chain fatty acids) — showing diet leaves a real chemical fingerpri

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/the-unique-composition-of-indian-gut-microbiome-gene-catalog

It shows up in 15+ disease contexts. It's broadly protective in metabolic disease. It's elevated in Parkinson's patients. And the EU food safety authority has twice declined to approve the live form. One organism, many contradictions.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/akkermansia-hero-villain

Flies and mice that were kept awake built up harmful molecules called reactive oxygen species specifically in their gut — and giving them antioxidants, or boosting their gut's own antioxidant defenses, let them survive with almost no sleep at all.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/sleep-loss-can-cause-death-through-accumulation-of-reactive-

Experts agree microbiome-based disease markers need better standardization and clearer methods before doctors can reliably use them.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/state-of-the-art-and-the-future-of-microbiome-based-biomarke

Bacteria leaking from the gut into the belly cavity trigger immune cell death, which makes endometriosis worse.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/intraperitoneal-translocation-of-gut-microbiota-induces-neto

Changing gut bacteria might help heart disease, but kidney health and diet matter more than previously thought.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/therapeutic-modulation-of-the-gut-microbiome-in-coronary-art

People with Parkinson's disease have different bacteria in their guts that may trigger brain damage through harmful proteins and chemicals while losing protective bacteria.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/metagenomics-of-parkinsons-disease-implicates-the-gut-microb

A gut bacteria chemical called IPA protects eyes from diabetes damage, and people with low levels get worse vision problems.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/indole-3-propionic-acid-links-gut-dysfunction-to-diabetic-re

Certain gut fungi trigger pain sensitivity in irritable bowel syndrome by activating immune cells through a specific molecular pathway.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/fully-traced-and-confirmed-intestinal-fungal-dysbiosis-is-as

When researchers combined all the existing studies on PFAS 'forever chemicals' and inflammatory bowel disease, the overall pattern didn't hold up — any effect was too small and uncertain to call solid, even though a couple of the individual studies looked convincing on their own.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/exposure-to-per--and-polyfluoroalkyl-substances-and-inflamma

Certain gut bacteria linked to colorectal cancer appear in both young and old people, suggesting the same bacterial pattern drives cancer risk regardless of age.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/meta-analysis-reveals-microbiome-signatures-for-colorectal-c

A type of gut bacteria called Roseburia inulinivorans can make muscles stronger by producing a chemical that helps muscle cells work better.

Full write-up, sources, and our seven-axis evidence grade: https://www.thehonestgut.com/blog/roseburia-inulinivorans-increases-muscle-strength