well, they've been doing it since long before Jesus, for one, so I doubt it's harmful. But the mind will/can make anything "bad", it's been proven many times-- and then that thing becomes poison. We could even argue that junk food with the right mentality could be an elixir: really! however, I do not think there are more than a handful of individuals ON THE PLANET AT THIS TIME that could demonstrate this to be true. (or would want to bother) And anyway, what would it prove?
ah, but what about the opposite?
Frankly, this is a bit of a twist, but still -- makes sense:
when Jesus (hope no one takes offense at his mention: I mean, as a Master, one who had great realization) was asked by his disciples, "what shall we put in our mouths?" (substitute ears, nose...even mind)he replied, "be more concerned about what comes out of your mouths." I do not think he meant purge. :-)
Just wanted to be clear on that, in case anyone reading is that way inclined.