Zinc-carnosine for gastric ulcers and leaky gut: the Japanese trial record

Zinc-carnosine (polaprezinc) is a chelated complex approved as a prescription anti-ulcer drug in Japan since 1994 and now sold internationally as a gut-health supplement. The Japanese ulcer trials are old but reasonably strong, and a small set of European trials supports its use in NSAID-induced gut barrier injury and H. pylori adjunctive therapy. Below, what is actually known.

What zinc-carnosine actually is

Polaprezinc is a 1:1 chelate of zinc and the dipeptide L-carnosine (beta-alanyl-L-histidine). The chelate is slowly released in the gastric environment, providing local zinc delivery to mucosal cells in a way that simple zinc salts do not. Animal and ex vivo data show membrane stabilization, free-radical scavenging, and stimulation of mucosal heat-shock proteins.

Gastric ulcer healing trials

Polaprezinc was approved in Japan based on multiple randomized comparisons against cetraxate, sofalcone, and cimetidine in patients with gastric ulcers. The pivotal multicenter trial showed an 8-week endoscopic healing rate of approximately 66% on polaprezinc versus 56% on cetraxate, a statistically significant difference [1]. Subsequent observational data confirmed similar healing rates in routine clinical use [2].

Adjunctive use with H. pylori eradication

A randomized trial in 66 H. pylori-positive ulcer patients found that adding polaprezinc 150 mg twice daily to standard triple therapy increased eradication rates from 76% to 94% [3]. The effect appears mediated by enhanced mucosal repair and possibly direct anti-H. pylori activity; the trial is small but consistent with other Japanese data.

NSAID-induced gastric and small-bowel injury

A UK proof-of-concept study in healthy volunteers found that zinc-carnosine 75 mg twice daily for 5 days protected against indomethacin-induced increases in gut permeability measured by lactulose-rhamnose ratio [4]. The effect size was meaningful and the trial methodologically tight. This protective effect on small-bowel barrier function is the strongest mechanistic evidence underpinning the supplement market beyond Japan.

Functional dyspepsia and reflux

Smaller trials have reported subjective improvement in dyspepsia scores with polaprezinc, but the effect sizes are smaller than for endoscopic ulcer healing and the trials are heterogeneous. There is no high-quality randomized evidence that zinc-carnosine improves reflux esophagitis.

Dosing and tolerability

Trials have used 75 mg twice daily (containing 16 mg elemental zinc per dose) or 150 mg twice daily for therapeutic indications. Adverse effects are infrequent and mild; constipation and nausea are most commonly reported. Long-term high-dose use risks the usual zinc-related copper deficiency, so courses beyond 3 months at supratherapeutic doses should be monitored.

The bottom line

Zinc-carnosine has reasonable trial evidence for accelerating peptic ulcer healing, augmenting H. pylori eradication, and protecting the small-bowel barrier from NSAID injury. Use at 75 mg twice daily for 4–8 weeks is the most clinically defensible pattern. It is not a substitute for a proton pump inhibitor when one is indicated, and copper status should be monitored on extended courses.