Background : Long‐term non‐steroidal anti‐inflammatory drug (NSAID) intake may induce increased intestinal permeability, eventually resulting in enteropathy. Because increased permeability might be related to cell damage resulting from energy depletion, it was hypothesized that glutamine—the major energy source of the intestinal mucosal cell—might prevent permeability changes. Methods : The 6‐h urinary excretion of 51Cr‐EDTA after an oral load of 51Cr‐EDTA was used in this study as a measure for intestinal permeability. Healthy volunteers underwent a series of permeability tests: (i) basal test; (ii) test following NSAID (indomethacin); (iii) test following NSAID in combination with glutamine and/or misoprostol. Results : The NSAID induced increased permeability in all volunteers. Pre‐treatment with glutamine (3 × 7 g daily, 1 week before NSAID‐dosing) did not prevent the NSAID‐induced increase in permeability. Multiple doses of glutamine close in time to NSAID‐dosing resulted in significantly lower permeability compared to the NSAID without glutamine. Co‐administration of misoprostol with the multiple‐dose scheme of glutamine resulted in a further reduction in the NSAID‐induced increase in permeability. Conclusions : Glutamine decreases the permeability changes caused by NSAID‐dosing when it is administered close in time, and misoprostol has a synergistic effect.