Max Bakker, a Master Cicerone explains the specific manner in which bottled beer should be poured into a glass so as to evade stomach ailments and bloating future on. The key is to release the CO2 within the brew. The best indication of this is a nice, foamy head. If a beer is served without a head, then the CO2 will remain trapped and only release when inside a person’s stomach.
You pour it down the sides with vigor and you’re breaking that co2 out. Granted people say that looks like a lot of foam, but the foam always turns into beer, and then I take that same bite of food and I try to have a swallow and it’s not agitating my stomach because I have broken that co2 out in the glass.