Background: The aims of this study were to investigate whether broccoli sprout extract containing sulforaphane (BSES) inhibits Helicobacter pylori (H. pylori ) infection density, and exerts an anti-oxidative effect on gastric mucosal damage. Methods: The enrolled subjects were randomized double blindly into three groups. finally, 33 H. pylori (+) BSES treatment subjects (group A), 28 H. pylori (+) placebo subjects (group B), and 28 H. pylori (-) BSES treatment subjects (group C) were studied. H. pylori infection density was quantifi ed indirectly by a C13-urea breath test (UBT) and measurement of the ammonia concentration in gastric juice aspirate through the gastroscopic examination. Malondialdehyde (MDA), as an oxidative damage biomarker, and reduced glutathione (GSH), as an anti-oxidant biomarker, were measured in gastric mucosa by ELISA. Results: BSES treatment did not signifi cantly affect UBT values or ammonia concentration in Group A (p=0. 634, p=0. 505, respectively). BSES treatment did signifi cantly reduce mucosal MDA concentrations in Group A (p<0. 05) and Group C (p<0. 001), while gastric mucosal GSH concentrations were not different before and after treatment in all three groups. Conclusions: BSES did not inhibit H. pylori infection density. However, BSES prevented lipid peroxidation in the gastric mucosa and may play a cytoprotective role in H. pylori -induced gastritis.