Podcast episode 151 (in German)
Larazotide – the bolt against the leaky gut, built on the model of a cholera toxin
November 28, 2026
A cholera vaccine that caused diarrhea even though the toxin had been removed led to a switch for the junctions in the gut wall. Larazotide was meant to close these junctions again and made it to the final testing phase in celiac disease — that is where the story ended, but not because of harm.
What it is about
The gut wall is a single layer of cells, with junctions in between that can open and close. In 1991 a laboratory in Baltimore came across a cholera protein that opens these junctions, and in 2000 the body’s own counterpart, zonulin. Larazotide, 8 amino acids in a capsule, was built as a bolt on the model of the bacterium and tested in celiac disease: as a safety net in addition to the gluten-free diet, not as a replacement. Surveys of people affected show that many want exactly such a net and that what weighs on them most is the constant vigilance when eating. The episode goes through the studies, from the puzzling result of the lowest dose level to the termination of phase 3, and shows why a widely used zonulin test measures something other than assumed. The conclusion: the biology is real, the safety net does not exist yet.
Key points
- What people affected want is shown by a survey of 486 people with celiac disease from 3 countries: just under 17 percent a pill for slip-ups, fewer than 10 percent a replacement for the diet.
- In the largest study before phase 3, with 342 adults over 12 weeks, only the lowest of 3 dose levels reduced the days with symptoms, by around a quarter; the higher ones did not.
- In 184 people who deliberately ate gluten for 6 weeks, larazotide did not change the sugar test for permeability; what improved were the symptoms, and the celiac antibodies rose markedly less.
- The phase 3 trial CedLara was planned for 525 people and was stopped on June 21, 2022, with 307 enrolled, for futility, not because of harm; in July 2023 the company went insolvent.
- In 12 children with a severe inflammatory reaction after Covid, abdominal symptoms resolved faster under 3 weeks of larazotide in addition to hospital treatment than under placebo.
- A Leipzig group used the most widely used zonulin test in 376 Sorbs: just under 16 percent cannot genetically produce this form of zonulin at all, yet showed the same values as everyone else.
Where the data stop
For gut complaints without a diagnosis, that is, for most people searching under the keyword leaky gut, there is not a single efficacy study and no validated test. The complaints are real, and an explanation brings relief; it just does not carry as far as it promises. In celiac disease, larazotide was tested in the most favorable situation and was not enough; why of all doses the lowest one worked, nobody can explain to this day. In the published studies, side effects were at placebo level. That does not apply to products from online shops that offer it as a research peptide “for laboratory use only”; larazotide is not approved anywhere.
The thread on Covid sequelae is open: the children’s study with 12 participants is a hint, not proof. A study in long Covid with 107 participants ended in June 2026; as of September 2026, no results were available. Anyone with celiac disease stays on the diet; when symptoms persist despite the diet, hidden gluten is the most common reason.
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Published on November 28, 2026.
The topic in the database
- The best-researched “leaky gut” peptide – and the most instructive: the phase 3 trial in celiac disease was stopped after an interim analysis for futility …Larazotide (AT-1001)
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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Content as of: 2026-09-25.