Peptides for Gut Health: BPC-157, KPV and Larazotide Ranked by Human Evidence

Which gut peptides actually have human evidence?

Start with legal status, because it frames everything else. BPC-157, KPV, larazotide and pentadeca arginate are not approved drugs in the US or anywhere else. On July 23, 2026, the FDA's advisory panel on pharmacy-made drugs voted 8 to 6 to add BPC-157 and KPV to the approved ingredient list, over the objection of the FDA's own staff. That vote is only advice, and no pharmacy can legally make them until the FDA finishes a new rule (our FDA status tracker has the documents). Teduglutide is the exception: an approved prescription drug for one narrow use. This article sorts the five by how much has been tested in people, not by how popular they are.

One thing to know before you read a table like this. A proper study in a few hundred people costs millions. That money almost always comes from whoever will own the drug at the end. Nobody can own some of these. They are a natural piece of a body protein, or a recipe published decades ago, or something already sold cheap. So nobody pays for the study, and the research stops at animals. For those, a missing study tells you how drug research gets paid for. It tells you nothing about whether the stuff works. That cuts both ways, just as hard. With no study, something that does nothing and something that causes a rare harm both look like something with no reported problems. No evidence here really means no evidence, in both directions. It is not a quiet thumbs up.

That fits BPC-157 and KPV exactly. Both are short sequences published decades ago and sold cheaply by dozens of suppliers. No company could earn back the cost of a study, so none has run one. Larazotide is the opposite case in the same article. It had a company paying, it got a mid-sized study and a big one, and the big one was stopped because it wasn't working. Having someone pay is what makes it possible to find out that something does not work.

How we sorted the evidence

• Proper study in people: people split into groups by chance, compared against a dummy treatment, with the goal set in advance.
• Small or watching-only study in people: small groups with nobody to compare against, or patient records looked at afterwards.
• Animal: rats, mice or larger animals with ulcers, colitis, surgical gut joins or a damaged gut lining.
• In a dish: cells or tissue in the lab.
• None: no published study of the substance itself.

Did larazotide work for celiac disease?

Larazotide (AT-1001) is a pill, a peptide eight building blocks long, that works inside the gut. It blocks zonulin, a protein that loosens the seals between gut cells. Tighter seals make it harder for pieces of gluten to slip through. It is by far the best-studied 'gut lining' peptide. The 2015 study, published in Gastroenterology (Leffler et al., NCT01396213), hit its main goal on a celiac symptom score only at the lowest dose. People on that dose also had 26 percent fewer days with symptoms, a side result the study also looked at. Side effects were about the same as the dummy pill (PubMed 25683116).

The big study, CedLara (NCT03569007), started in May 2019 under 9 Meters Biopharma. It tested 0.25 mg and 0.5 mg three times a day against a dummy pill, looking at belly symptoms after 12 weeks. On June 21, 2022, with roughly half of the planned 525 patients signed up (307 by the final count), an independent check-in found that the number of extra patients needed to show a difference was 'too large to support trial continuation'. The company stopped the study (9 Meters press release, SEC filing). No results on whether it worked were reported, and we found no later big study. Larazotide is still unapproved.

Which gut peptides are FDA-approved?

Teduglutide matters here as the measuring stick. It is a copy of GLP-2 that grows the gut lining. The FDA approved it on December 21, 2012 (NDA 203441). In STEPS, people on it cut their IV feeding by 4.4 liters a week on average, against 2.3 on a dummy shot, at week 24 (PubMed 22982184). It carries warnings about gut growths (polyps) and blockages. That is a reminder that a peptide strong enough to change gut tissue is strong enough to need a doctor watching.

Does BPC-157 heal the gut in humans?

BPC-157 is a 15-building-block piece of a protein found in human stomach juice, and gut healing is where its research began. A 2025 review in HSS Journal searched studies from 1993 to June 2024 and found 36 that qualified. 35 were in animals or the lab. One was in people: patient records in which 7 of 12 people given a knee shot for long-term knee pain said the relief lasted more than six months (PubMed 40756949). A second 2025 review counted three small studies in people in total: the knee report, a painful bladder study and a safety test of a drip into the vein (PubMed 40789979). None was about the gut. The FDA's July 2026 staff paper looked at BPC-157 for ulcerative colitis, advised against adding it to the pharmacy list and raised worries that shots could trigger the immune system (FDA briefing document).

In rats, the record is long. The Zagreb group led by Predrag Sikiric has published rat studies for more than 25 years. They show protection against stomach ulcers, healing of surgical joins in the colon and small bowel, and closing of abnormal tunnels between organs (fistulas). In the 2007 study, rats given BPC-157 into the belly at 10 micrograms or 10 nanograms per kilogram healed better on every measure over 14 days (PubMed 17713731). The same paper says the peptide was 'shown to be safe in clinical trials for inflammatory bowel disease (PL-10, PLD-116, PL14736, Pliva, Croatia)'. Those are the closest BPC-157 has come to a gut study in people, and no results on whether it worked have ever appeared in a journal.

Pentadeca arginate is the same 15-building-block sequence as BPC-157, paired with an arginine salt instead of acetate. It showed up after the FDA banned BPC-157 for pharmacies in 2023, sold as a legal alternative. Nobody has studied the arginine version in any species. It has no evidence of its own. At best, it borrows BPC-157's animal results.

What does KPV do for colitis?

KPV is the last three building blocks (Lys-Pro-Val) of a skin-darkening hormone called alpha-MSH. The FDA reviewed it for 'wound healing and inflammatory conditions' as a cream or gel. FDA staff wrote that they 'did not identify data, such as clinical studies, on the use of KPV in humans'. They found no data on how the body handles it, no single-patient reports and nothing in the FDA's side-effect database through December 3, 2025. They advised against listing it (FDA KPV briefing document). The panel voted 8 to 6 the other way. Its reason was that a pharmacy is safer than the gray market, not that KPV works.

One detail is worth keeping straight. The parent hormone, alpha-MSH, has been tested in people. A lab-made copy of it, afamelanotide, has been an approved prescription drug since October 8, 2019 (FDA NDA 210797). That is not evidence for KPV. Afamelanotide works through a receptor called MC1R, and KPV lacks the part that fits that receptor. That is exactly why FDA staff treated KPV as untested. For what a regulated gut-inflammation peptide program looks like, PL8177, a pill that does work on MC1R, reached a mid-sized study in ulcerative colitis. It is small and unfinished, but it is a real study.

The Dalmasso 2008 paper is the one everyone cites, and it is a good one. In a dish, it showed that a gut transporter called PepT1 carries KPV into gut and immune cells, and that KPV turns down inflammation signals in two human cell lines, Caco2 and Jurkat. In mice, KPV by mouth reduced gut inflammation and inflammation chemicals in two kinds of colitis (PubMed 18061177).

The bottom line

If the question is 'which gut peptide has been shown to work in people', the honest list is short. Teduglutide, for one rare disease. Larazotide, for celiac symptoms in one mid-sized study that its own big study could not confirm. Then a cliff. BPC-157's rat results are real and consistent, and they are still rat results. KPV's colitis results are from 2008, and from mice. The July 2026 votes changed a legal conversation, not the evidence. For side effects by peptide group, see peptide side effects by class. For what a vial's lab certificate can and cannot tell you, see how to read a peptide COA.