Researchers concluded that: (1) the protective activity of L-arginine involves gastric hyperemia (blood flow increase) mediated by NO (nitric oxide) and a mild irritant effect due to enhanced generation of endogenous prostaglandins, and (2) the ulcer healing properties of L-arginine depend upon its hyperemic and angiogenic actions, possibly involving NO.
Brzozowski T, Konturek SJ, Sliwowski Z, Drozdowicz D, Zaczek M, Kedra D. Role of L-arginine, a substrate for nitric oxide-synthase, in gastroprotection and ulcer healing. J Gastroenterol. 1997 Aug;32(4):442-52.
Sukumar P, Loo A, Magur E, Nandi J, Oler A, Levine RA. Dietary supplementation of nucleotides and arginine promotes healing of small bowel ulcers in experimental ulcerative ileitis. Dig Dis Sci. 1997 Jul;42(7):1530-6.