Gut health
Fiber and peppermint oil have real trials. The gut peptides have mouse studies.
The short version
Psyllium fiber and peppermint oil have helped people with IBS in pooled trials. Some probiotics cut diarrhea from antibiotics by about a third. "Leaky gut syndrome" is not an accepted diagnosis. BPC-157 and KPV have no published human gut studies.
What has proof
Psyllium (soluble fiber)
A review of 14 trials in 906 people with IBS found soluble fiber such as psyllium helped about 1 extra person in every 7. Bran did not help. For constipation, a review of 16 trials in 1,251 adults found about 66% improved on fiber, against 41% without it, with more gas.
cheap, and it helped about 1 extra person in 7
Peppermint oil
A review of 10 trials in 1,030 people with IBS found it beat placebo for overall symptoms and for belly pain. Side effects were also more common, and the reviewers rated the quality of the evidence as very low.
Probiotics
For diarrhea caused by antibiotics, a review of 42 trials in 11,305 adults found the risk fell by about a third, and only certain species worked. For IBS, a review of 82 trials found some strains may help, but the certainty was low to very low.
which germ is in the bottle matters
Glutamine
One 8-week trial in 106 people who got diarrhea-type IBS after a gut infection: about 80% improved on glutamine, against 6% on placebo, and a gut-leakiness test improved. The authors called for larger trials. Ten smaller studies in other illnesses, pooled, showed no clear change in leakiness.
one striking trial, waiting on bigger ones
Zinc carnosine
Two tiny studies, in 10 and 8 healthy people, found it kept the gut from getting leakier after a painkiller or hard exercise. A larger trial in 303 patients, with no blinding, found it helped antibiotics clear a stomach germ. None measured healing of the stomach lining.
Digestive enzymes
One small trial in 18 healthy people found enzyme capsules meant less bloating after a very fatty meal. The larger trial, in 120 people, was in people who already had indigestion.
Gym lore, checked
Gym lore is what people say, not what we recommend. Each one is followed by what studies in people show. Stories are real experiences. They are not proof.
"leaky gut syndrome is behind fatigue, brain fog and autoimmune disease"
A real measurement. Not an accepted diagnosis. Doctors can measure a leakier gut lining in some bowel diseases and after stress such as endurance exercise. But reviews say three things. "Leaky gut syndrome" is not an accepted diagnosis. There is no proven test for it. And fixing the lining has not been shown to improve any disease.
"BPC-157 heals your gut"
In animals. Almost everything known about BPC-157 and the gut comes from animals. A 2026 review found three weak human studies of BPC-157, 30 people in total, and none was about the gut. Reviews by its developers mention a mid-stage colitis trial, but we found no published results.
"KPV calms gut inflammation"
In mice. KPV given by mouth lowered inflammation in mice with chemically caused colitis, in studies from two teams. We found no human study, published or registered.
"collagen and bone broth heal the gut"
Not shown. A study with no comparison group started with 40 women, and only 14 finished. A fairer trial in 20 runners found no difference in gut leakiness, gut injury markers or symptoms. We found no bone broth trial in people.
"there's a peptide that seals a leaky gut"
The closest one was dropped. Larazotide was tested in celiac disease. Mid-stage trials gave mixed results and did not change the gut-leakiness test. The final-stage trial, which enrolled 307 people, was stopped by the company in 2022 and no results were posted.
What we don't know
- Whether BPC-157 or KPV does anything for the human gut.
- Which probiotic helps which problem. Most have not been compared head to head in the trials we found.
- Whether fixing a "leaky" test result changes how anyone feels.
Sources
- Fiber for IBS, review of 14 trials. American Journal of Gastroenterology, 2014. Journal page
- Fiber for constipation, review of 16 trials. American Journal of Clinical Nutrition, 2022. Journal page
- Peppermint oil for IBS, review of 10 trials. Alimentary Pharmacology and Therapeutics, 2022. Journal page
- Probiotics for IBS, review of 82 trials. Gastroenterology, 2023. Journal page
- Probiotics and antibiotic diarrhea, review of 42 trials. BMJ Open, 2021. Journal page
- Glutamine for IBS after infection, trial. Gut, 2019. Journal page
- Glutamine and gut permeability, review of 10 trials. Amino Acids, 2024. Journal page
- Zinc carnosine and painkiller gut damage. Gut, 2007. Journal page
- Zinc carnosine and exercise. American Journal of Clinical Nutrition, 2016. Journal page
- Zinc carnosine with antibiotics, trial in 303 patients. PLoS One, 2017. Journal page
- Enzymes after a fatty meal, trial in 18 volunteers. Digestive Diseases and Sciences, 1999. Journal page
- Enzyme blend in indigestion, trial in 120. Biomedicine and Pharmacotherapy, 2023. Journal page
- Leaky gut: mechanisms, measurement and clinical meaning. Gut, 2019. Journal page
- Leaky gut, a second review. PubMed
- BPC-157 in humans, 2026 systematic review. Acta Orthopaedica Belgica. Journal page
- KPV in mouse colitis. Gastroenterology, 2008. Journal page
- KPV in mouse colitis, second team. Inflammatory Bowel Diseases, 2008. Journal page
- Collagen and digestive symptoms, uncontrolled study. JMIR Formative Research, 2022. Journal page
- Collagen in runners, controlled trial. European Journal of Nutrition, 2023. Journal page
- Larazotide in celiac disease, mid-stage trial. Gastroenterology, 2015. Journal page
- Larazotide final-stage trial, registry entry NCT03569007. ClinicalTrials.gov
Studies found on PubMed. Last checked November 12, 2026. Information only. Not medical advice.