SummaryBackgroundGastric and duodenal ulcerations are common during multiple‐dosing aspirin treatment, such as for prevention of cardiovascular disease. On capsule endoscopy, oral administration of the bacterial strain Bifidobacterium breve Bif195 (DSM 33360) reduced the risk of aspirin‐induced small intestinal damage, without affecting cyclo‐oxygenase‐2 (COX‐2) inhibition.AimTo evaluate endoscopically the effect of Bif195 on aspirin‐induced stomach and duodenal mucosal damageMethodsTwenty‐five healthy volunteers underwent two intervention periods in a randomised, double‐blind, placebo‐controlled crossover design including four gastroduodenoscopies and 6 weeks washout. Each intervention was a 4‐week oral co‐treatment of aspirin 300 mg daily and Bif195 (≥10¹¹ colony‐forming units daily) or placebo. Primary endpoint was change in Lanza score ‐ ranging from 0 (normal mucosa) to 4 (>10 erosions or ulcer).ResultsAll 25 participants (56% females); age 27.3 (±4.8) years; BMI 23.2 (±3.4) kg/m², completed the trial exhibiting significant increases in Lanza scores during placebo treatment as compared to baseline. Bif195 reduced gastric Lanza score with an odds ratio of 7.2 (95% confidence interval 1.72–30.08, p = 0.009) compared to placebo with no related adverse events. There were no significant changes in Lanza scores in the duodenum.ConclusionsBif195 reduces aspirin‐induced gastric mucosal damage and may serve as a safe supplement during multiple‐dosing aspirin treatment.