SLC6A19 and colitis: In addition, nicotinamide and dietary tryptophan appear to exert effects on colitis and diarrhea prevention via SLC6A19/B0AT1‐ACE2/mTOR‐related pathway, and on the regulation of intestinal cell proliferation, differentiation, migration, and cytoskeletal reorganization (Cole‐Jeffrey et al., 2015; Hashimoto et al., 2012; Kowalczuk et al., 2008; Wu, 2009).