The only grains I avoid are the ones that contain gluten. I eat all others, including rice daily.
I don't need a scientific study to tell me shitting blood, undigested food, intestinal pain, and my sinuses closing up means I shouldn't do something.
If gluten is harmless to you, or you want to eat it anyway, knock yourself out. Why do you care what we do?
Are you the type of person that lectures people wherever you go about how everyone should do things the way you do? Or only on the web, where you don't have to see people rolling their eyes at you?