Interesting! My daughter and I have stomach and digestive issues also and I read b1 specifically helps with her ulcerative colitis. I believe stuttering is genetic as my uncle and grandfather both stutter as well as myself. I wonder if the mthr gene mutation has abutting to do with this? My dad couldn’t handle synthetic vitamins at all. I notice when I take vitamins that are synthetic I do stutter more. I will find a non synthetic b complex and try it out and report back!