Larazotide

What it is

Larazotide acetate is a synthetic eight-amino-acid peptide derived from the Vibrio cholerae zonula occludens toxin (Zot), developed by the Alessio Fasano lab at Mass General as a zonulin antagonist [PMID 33397225]. Zonulin is the human protein that regulates the tight junctions between intestinal epithelial cells — the seams that decide whether the gut wall acts as a sealed barrier or as a leaky one. When zonulin signaling is upregulated (by gluten in celiac disease; by dysbiotic gut bacteria; by chronic stress in functional-medicine practice), those tight junctions loosen, and contents that should stay in the gut lumen — including bacterial lipopolysaccharide (LPS) — can translocate into circulation. Larazotide works directly at the gut-luminal side of those junctions to oppose that loosening.

It’s the most clinically-tested peptide explicitly targeted at the leaky-gut mechanism. The evidence story is unusual: positive in early human trials, mixed in Phase 2, and discontinued for futility in Phase 3 — yet the molecule remains in active use in the functional-medicine practitioner community as a research-use-only or compounded peptide for leaky-gut-related complaints. That’s the gap this article covers honestly.

How it works

Larazotide is an orally-administered, minimally-absorbed peptide that acts locally at the intestinal epithelium. This is important: it is NOT a systemic drug. It does not “tighten tight junctions throughout the body” — that’s a popular practitioner-camp overstatement. Its action is confined to the gut lumen.

The mechanism, as best characterized by the Fasano group, is competitive antagonism of zonulin at the intestinal epithelial surface [PMID 33397225]. The fine-grained molecular binding model (allosteric vs. orthosteric; specific receptor identity) is not fully crisply pinned in the published abstract literature and is against full-text Fasano review papers.

What matters for the OHM reader: larazotide doesn’t kill bacteria, doesn’t suppress inflammation directly, and doesn’t repair damaged tissue. It closes the gate at the seams. In the leaky-gut cascade (zonulin loosens junctions → LPS translocates → systemic inflammation → insulin resistance → hepatic fat storage), larazotide is the most mechanism-targeted tool for the upstream end. Everything else — BPC-157 for tissue, KPV for inflammation, LDN for immune calm-down, elimination diet for the substrate — addresses downstream consequences or removes upstream triggers; larazotide addresses the wall itself.

What the research shows

The clinical story honestly:

Phase 2 — mixed but partially positive:

• Kelly 2013 (Aliment Pharmacol Ther, gluten-challenge trial) [PMID 23163616]: 86 celiac patients in remission on a gluten-free diet, challenged with daily gluten while taking larazotide vs placebo. Reduced gluten-induced symptoms and immune reactivity, but the primary endpoint (LAMA urinary permeability ratio) was NOT met. Symptoms improved; the permeability marker did not.
• Leffler 2015 (Gastroenterology, the strongest single trial) [PMID 25683116] (DOI 10.1053/j.gastro.2015.02.008): 342 adults with persistent celiac symptoms despite a strict gluten-free diet, randomized to three doses (0.5 / 1 / 2 mg TID) vs placebo for 12 weeks. The lowest dose (0.5 mg TID) met the primary endpoint for celiac-symptom-severity reduction vs placebo (p=0.022). The two higher doses did NOT — an inverted dose-response that became a recurring concern in subsequent trial designs.

That inverted dose-response (lower dose wins) is genuinely unusual in clinical pharmacology and is one of the open scientific questions about larazotide’s mechanism. It also informs the Phase 3 outcome.

Phase 3 — discontinued for futility (June 2022):

The CeDLara trial (NCT03569007) was the pivotal Phase 3 study: 525 adults with persistent celiac symptoms, randomized to 0.25 mg or 0.5 mg larazotide TID vs placebo, primary endpoint = mean change in CeD PRO abdominal-domain score over 12 weeks. In June 2022, sponsor 9 Meters Biopharma announced that a pre-specified interim analysis had found futility — continuing the trial would not yield a statistically significant difference between larazotide and placebo within feasible enrollment. The trial was discontinued at the interim, not formally failed at final readout. Functionally the difference is small; commercially it was the end of the celiac program.

Following CeDLara’s discontinuation, 9 Meters Biopharma effectively shelved the larazotide program. No active sponsor pipeline for larazotide in celiac exists as of mid-2026.

Off-celiac human evidence — thin:

• Pediatric MIS-C (COVID-related Multisystem Inflammatory Syndrome in Children) — Naveed et al. 2022, Critical Care Explorations [PMID 35211683]. A single case-series of adjuvant larazotide use in pediatric MIS-C patients. Anecdotal, not controlled — included for completeness, not as efficacy evidence.
• NAFLD / NASH / IBS / IBD / T1DM — applications cited in review articles (notably the Troisi/Fasano 2021 review at [PMID 33397225]) are supported by preclinical or mechanistic reasoning only. No published controlled human trials outside celiac disease as of this verification pass (2026-06-26). Practitioner-camp off-label use exists; published efficacy data for those indications does not.

Honest practitioner-camp framing of why the molecule still gets used despite the Phase 3 outcome: the leaky-gut hypothesis (and zonulin’s role) is broader than the celiac-disease use case the Phase 3 was designed to test. CeDLara tested whether larazotide could reduce persistent celiac symptoms in an established-celiac population already on a gluten-free diet — a high-bar endpoint where multiple confounders (diet quality variability, baseline severity, placebo response) likely contributed to the null. Functional-medicine practitioners use larazotide for non-celiac leaky-gut presentations where the upstream zonulin signal may be more responsive. Whether that practitioner-camp use is justified by the available evidence is a real open question — the mechanistic case is plausible; the controlled-trial evidence for non-celiac indications does not exist yet. Tier-honest framing: practitioner-camp use is-tier for non-celiac applications. The reader should know that.

The leaky-gut → systemic inflammation cascade (upstream context)

Larazotide makes the most sense inside the broader gut-liver-axis cascade that Jones and other functional-medicine practitioners use as their organizing framework:

leak → inflame → resist → store

1. Leak. Zonulin-mediated tight-junction loosening lets bacterial LPS and other gut contents translocate into the portal circulation.
2. Inflame. Circulating LPS triggers the innate immune system (TLR4/CD14 axis) and drives chronic low-grade systemic inflammation — the metabolic endotoxemia phenotype first formally characterized by Cani et al. 2007 in Diabetes [PMID 17456850] in a high-fat-diet mouse model.
3. Resist. Chronic systemic inflammation impairs insulin signaling — insulin resistance.
4. Store. Elevated insulin signals fat storage, particularly in the liver (hepatic steatosis / MASLD) and visceral depots.

The loop can feed itself: the inflamed fatty liver produces more inflammatory cytokines, which further compromise gut-barrier integrity. This is the cascade the OHM functional-medicine lean takes seriously.

Honest tier-check on the cascade: the mechanism is well-established in animal models. The human evidence is associational, not causal — patients with T1DM and T2DM show elevated fasting LPS compared to non-diabetic controls (Gomes 2017 systematic review, Metabolism [PMID 28183445]), but study heterogeneity is substantial and direct causal proof in humans is incomplete. The Diabetologia 2015 commentary by Hersoug [PMID 26133659] explicitly questioned whether the cascade is clinically meaningful in humans at the magnitude functional-medicine practice assumes. OHM’s editorial line: this is biologically established in animals, suggestive in humans, not yet proven causal — present it that way, not as settled human pathophysiology.

That honest framing is exactly why larazotide is interesting and also why the Phase 3 outcome wasn’t a clean win: if the cascade is real but operates at smaller magnitudes than animal models suggest, a 12-week Phase 3 endpoint in chronic celiac patients may not be where the effect is most demonstrable.

Real-world use

Because no FDA-approved larazotide product exists, the only access routes in the US are research-use-only peptide or 503A/503B compounding-pharmacy prescription (off-label). Practitioner-camp protocols draw on the Phase 2 dose-finding work:

• Trial-supported dose: 0.5 mg three times daily, before meals, oral. This is the Leffler 2015 dose that hit primary endpoint in celiac.
• Cycle length: Phase 2/3 trials used 12-week treatment courses. Practitioner-camp protocols range from 4-week “gut reset” courses to longer maintenance use.
• Higher doses are not better — the inverted dose-response in Leffler 2015 means escalating past 0.5 mg TID may reduce, not increase, effect.

Most practitioners pair it with a foundational elimination diet (commonly 21-30 days, removing the dietary triggers that drive zonulin upregulation in the first place) and the other gut-stack peptides: BPC-157 for tissue support, KPV for quieting inflammatory signaling, Low-Dose Naltrexone (LDN) — the immune-modulation bridge for autoimmune patients on GLP-1s for immune system recalibration. The unifying principle from the practitioner camp: larazotide closes the gate, but if the dietary signal that opens the gate keeps coming, the tool is fighting the trigger rather than letting the system reset.

The doses and uses above are for educational and informational purposes only. Larazotide is sold for research use only or available only as a compounded prescription product. This is not medical advice. Consult a qualified physician before beginning any protocol.

Side effects & safety

The Phase 2/3 trials reported a generally favorable safety profile — headache and urinary tract infections were the most common adverse events, broadly comparable to placebo rates. No serious adverse events attributable to larazotide were reported at the doses tested. Because it’s gut-lumen-restricted with minimal systemic absorption, the side-effect profile reflects local-GI events rather than systemic drug effects.

Pregnancy, lactation, pediatric (outside the MIS-C case-series setting), and combination with immune-modulating drugs are unstudied territories. The standard “consult a qualified physician familiar with peptide therapy” caveat applies — particularly if the user is already on immunosuppressants, biologics, or active treatment for celiac or other inflammatory bowel disease.

The absence of long-term human safety data outside the celiac trial populations is the real unknown — most off-label functional-medicine use happens without the kind of structured safety surveillance the formal trials carried.

Vendor mapping

Larazotide is harder to source cleanly than the bigger peptides in OHM’s catalog. Verified vendor mapping as of 2026-06-26:

• BioLongevity Labs — BioGutPro combination product (biolongevitylabs.com/product/biogutpro). Contains 500 mcg N-Acetyl-Larazotide per 2-capsule serving, combined with BPC-157 1,000 mcg, KPV 500 mcg, GHK-Cu 2 mg, CoreBiome tributyrin 400 mg, sodium bicarbonate 150 mg, and zinc carnosine 100 mg. 60 capsules per bottle. Currently $179.98 on sale (list $299.97). Per-batch COA, third-party HPLC purity + LC-MS identity confirmation. Sold research-use-only.com/biolongevity`.
  • Important precision: BioGutPro contains N-Acetyl-Larazotide — an acetylated stability variant of the peptide — at a 500 mcg combination-product dose, not the 500 mcg TID monotherapy used in the Leffler 2015 trial. This is meaningful: the BioGutPro dose pattern does not replicate the trial-validated protocol, and the combination format means the effect attributable to larazotide alone vs the supporting peptides + tributyrin + zinc carnosine cannot be isolated. The product is a reasonable practitioner-camp gut-stack assembly; it is not the trial dose.
• Alyve Peptides — UNCONFIRMED. Catalog is gated behind a researcher-verification login; no public-facing search confirms larazotide presence or absence. Action: log in to verify; if confirmed, the OHM-15 Alyve coupon applies. Recheck queued.
• AminoClub — UNCONFIRMED. Same gated-catalog situation. Action: log in to verify; if confirmed, the OHM coupon applies. Recheck queued.

Until Alyve and AminoClub status is confirmed, the only reliable OHM-aligned commercial pathway for larazotide is BioGutPro at BioLongevity, with the precision caveats above. If a reader wants the trial-validated monotherapy dose pattern (0.5 mg larazotide acetate TID), that’s currently a 503A/503B compounding-pharmacy prescription route, not a research-chem route — and that requires a clinician relationship.

Regulatory status

No FDA approval for any indication. Larazotide acetate has never been approved for human use anywhere. Following the June 2022 CeDLara Phase 3 futility readout, 9 Meters Biopharma effectively shelved the celiac program; no active sponsor pipeline exists as of mid-2026.

In US commerce, larazotide exists in two channels:

1. Research-use-only (RUO) peptide from peptide vendors — the legal framing under which Alyve / BioLongevity / AminoClub sell most peptides in their catalogs. Not for human use per the FDA framing; widely used off-label by informed adults.
2. 503A / 503B compounding-pharmacy prescription — off-label, requires a clinician relationship, generally more expensive than research-chem channels but legally cleaner.

There is no anticipated FDA approval timeline. The molecule’s celiac evidence base did not clear the Phase 3 bar; without a sponsor running a new trial for a different indication, the regulatory status is stuck at “investigational and effectively shelved.”

Sources

• Mechanism + review: Troisi J, Venutolo G, Terracciano C, Delli Carri M, Di Micco S, Landolfi A, Fasano A. “The Therapeutic use of the Zonulin Inhibitor AT-1001 (Larazotide) for a Variety of Acute and Chronic Inflammatory Diseases.” Curr Med Chem. 2021;28(28):5788-5807. PMID 33397225. DOI 10.2174/0929867328666210104110053. (Aliases, mechanism, application landscape.)
• Phase 2 gluten-challenge: Kelly CP et al. “Larazotide acetate in patients with coeliac disease undergoing a gluten challenge: a randomised placebo-controlled study.” Aliment Pharmacol Ther. 2013;37(2):252-262. PMID 23163616.
• Phase 2 persistent symptoms (the strongest single trial): Leffler DA et al. “Larazotide Acetate for Persistent Symptoms of Celiac Disease Despite a Gluten-Free Diet: A Randomized Controlled Trial.” Gastroenterology. 2015;148(7):1311-1319.e6. PMID 25683116. DOI 10.1053/j.gastro.2015.02.008.
• Phase 3 CeDLara discontinuation: NCT03569007 trial registry. Sponsor 9 Meters Biopharma press release, June 21 2022, announcing pre-specified interim futility analysis and discontinuation.
• MIS-C case series: Naveed et al. Critical Care Explorations 2022. PMID 35211683.
• Metabolic endotoxemia foundational paper: Cani PD et al. “Metabolic endotoxemia initiates obesity and insulin resistance.” Diabetes. 2007;56(7):1761-1772. PMID 17456850. DOI 10.2337/db06-1491.
• Metabolic endotoxemia human systematic review: Gomes JMG, Costa JA, Alfenas RCG. “Metabolic endotoxemia and diabetes mellitus: A systematic review.” Metabolism. 2017;68:133-144. PMID 28183445. DOI 10.1016/j.metabol.2016.12.009.
• Metabolic endotoxemia honest counter-position: Hersoug LG. “Metabolic endotoxemia with obesity: is it real and is it relevant?” Diabetologia 2015. PMID 26133659. (Documents the human-evidence limitations of the cascade — included for the umbrella “capture both sides” doctrine.)
• Video source: — Dr. Jones DC YouTube, 14:44.
• Vendor mapping (verified 2026-06-26): BioLongevity Labs BioGutPro product page (biolongevitylabs.com/product/biogutpro/). Alyve and AminoClub status pending login-gated catalog check.

Related articles: BPC-157 · KPV · Low-Dose Naltrexone (LDN) — the immune-modulation bridge for autoimmune patients on GLP-1s · Retatrutide · Immune cluster — LL-37, KPV, VIP (the anti-inflammatory / antimicrobial trio).