Zinc-L-carnosine
Zinc-L-carnosine (polaprezinc), zinc and carnosine chelate
Written by Aaron CuhaReviewed Sep 2026
Also known as: Polaprezinc, PolaPreZinc, Zinc carnosine, L-CAZ
A zinc and dipeptide chelate approved as a gastric drug in Japan, with a randomised phase 3 showing it prevented radiotherapy-induced swallowing difficulty in breast cancer patients.
Overview
Zinc-L-carnosine sits in an unusual regulatory position. It is an approved prescription drug for gastric ulcer in Japan, where it has been used since 1994, and it is sold as a dietary supplement in the United States. Same molecule, two categories, which is a distinction worth noticing when reading claims about it.
The compound is a chelate of zinc and L-carnosine, the dipeptide of beta-alanine and histidine. The chelate matters: it adheres to damaged mucosa and releases zinc locally, which is a different proposition from taking zinc and carnosine separately.
The evidence highlight is a randomised phase 3 in breast cancer patients undergoing adjuvant radiotherapy, where it prevented dysphagia. That is a real randomised result with a clinically meaningful endpoint in a defined population, which is more than most gut-healing supplements have.
Mechanism of action
A one-to-one chelate of zinc and L-carnosine. The chelate adheres preferentially to ulcerated and inflamed mucosal surfaces, where it dissociates and releases zinc locally at higher concentration than systemic zinc dosing would achieve. Zinc contributes to epithelial repair, membrane stabilisation and antioxidant defence through metallothionein induction, and carnosine has direct antioxidant and metal-chelating activity. In cell and animal work it accelerates epithelial migration and restitution, and it raises heat shock protein expression. Note that its actions are largely local to mucosa, which is why the evidence concerns gut and mucosal injury rather than systemic outcomes.
Human evidence
A long approved-drug record in Japan for gastric ulcer, plus randomised evidence in radiotherapy-induced mucosal injury. Thin evidence for the general gut-health claims it is sold on.
- Approved and used in Japan as a prescription gastric ulcer treatment since 1994.
- A randomised phase 3 found it prevented dysphagia in breast cancer patients undergoing adjuvant radiotherapy.
- Smaller human work has examined intestinal permeability, including in the context of nonsteroidal anti-inflammatory drug injury.
- Well tolerated in the trials reported, which is consistent with a locally acting agent at modest zinc doses.
- No trial has examined ageing, longevity or any systemic outcome.
What this does not tell you: The strongest evidence concerns mucosa exposed to a defined injury, radiotherapy or ulceration, which is not the same as a healthy person taking it for general gut health. The intestinal permeability literature is small and mostly uses surrogate markers. Because it is a supplement in the United States, product zinc content and chelate integrity are not verified by anyone, which matters more for a chelate than for a simple salt since the local-release mechanism depends on the complex being intact.
Reading the research record
This compound is a useful test of the site's own standard, because its evidence is better than most supplements and worse than its marketing. It has a randomised phase 3 with a patient-relevant endpoint, which puts it ahead of nearly everything sold for gut health. That trial was in breast cancer patients receiving radiotherapy, a population with a specific and severe mucosal insult, and the finding was prevention of a specific complication.
That does not transfer cleanly to a healthy person taking it for leaky gut, which is the claim it is most often sold on and the one with the least support. It also does not transfer to taking zinc and carnosine separately, since the mechanism depends on the chelate reaching mucosa intact. Both distinctions get lost in the marketing.
The evidence, charted
Fig. 1 · evidence composition
1of 1 citation (100%) is in people
Every citation cited here is Human work; no other study type is cited on this page. This count is of our own citation list and understates any literature larger than the sources we cite.
Fig. 2 · evidence over time
Every citation here was published in 2020.
Too few distinct publication years on this page to plot as a timeline. The newest citation on file is from 2020, more than five years ago; the published record may have gone quiet.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four jurisdictions shown. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Key studies & citations
- Human2020
Zinc-L-carnosine prevented dysphagia in breast cancer patients undergoing adjuvant radiotherapy: results of a phase III randomized trial
A randomised phase 3 trial in breast cancer patients receiving adjuvant radiotherapy, reporting prevention of dysphagia. A real randomised result with a symptom endpoint that matters to patients, in a specific population receiving a specific mucosal insult.
The Breast Journal
Frequently asked questions
Is zinc-L-carnosine a drug or a supplement?
Both, depending on the country. It is an approved prescription gastric medicine in Japan and a dietary supplement in the United States. That is why claims about it sometimes cite drug-grade evidence while the product you can buy is not regulated as a drug.
Does it fix leaky gut?
That is the claim with the least support. The strong evidence concerns mucosa under a defined injury, ulcers and radiotherapy, and the intestinal permeability work in healthy people is small and uses surrogate markers. Nothing establishes a benefit for a healthy person taking it generally.
Can I just take zinc and carnosine separately?
Not equivalently, on the mechanism. The proposed action depends on the intact chelate adhering to damaged mucosa and releasing zinc locally at higher concentration than systemic dosing achieves. Taking the two components separately is a different intervention and has not been tested against the chelate.