Every once in a while I'll look up from praying before (or even during) Communion and I see someone chewing gum. I'm not talking about kids; I'm talking about adults, even Extraordinary Ministers of the Eucharist!
According to Canon 919, the Church generally expects people to fast from all food and drink (except water) one hour prior to receiving communion.
Now, I am not saying that we should commission a posse of "liturgical police," but I believe we have an obligation to gently and pastorally correct our fellow Catholics. I suspect that most of them simply do not know better because someone did not care enough to let them know.
I like what St. Josemaria said about correcting our fellow Christians:
It happens, however, that some people (who are good, or should we rather say 'goodish') pay lip service to the beautiful ideal of spreading our faith, but in practice they make do with a superficial and careless professional output. They seem scatterbrained. If we happen to come across such Christians, we should do our best to help them, affectionately but uncompromisingly, having recourse where necessary to the gospel remedy of fraternal correction: 'Brethren, if a man is found guilty of some fault, you who are spiritually minded ought to show a spirit of gentleness in correcting him. Have an eye upon thyself, lest thou too be tempted. Bear one another's burdens and so you will be fulfilling the law of Christ.' If besides the fact that they claim to be Catholics there are other factors involved, because, for instance, those at fault are older, or have more experience or responsibility, then there is all the more reason to talk to them. We should try to get them to react, helping them take their work more seriously, trying to guide them, like a good parent does or a teacher, but without humiliating them. (Friends of God, #69)
