You are definitely not supposed to have papers printed out for them. You might refer to a study you read, yes, but bringing print-outs is over the top even if you are a colleague of some sort.
This is the right advise for more unproven or controversial stuff like supplements or certain diets, but it’s the wrong advice for other stuff like medications. For instance, if your doc says that one med (which doesn’t work for you) is just as effective another med that you want to try but that he’s unwilling to prescribe, the only way to change your doc’s mind is to print out and highlight the exact text where his colleagues (especially if they know more about this med than he does) disagree with his opinion.
Many docs might dig in, and if they don’t change their attitude and opinion when they should, you’ll just need to switch docs until you find a decent one. The doc I brought the print out to didn’t dig in and prescribed the med I requested after he read it. This had nothing to do with any study; it seemed that it was widely known among experts (the print out quoted expert opinion), but this doc just had the wrong opinion about it. I asked another doc about a combination of meds that’s usually not prescribed often (but probably should be) to younger age groups and the reasoning behind it without showing a print out (but I had one just in case) and he agreed even though it wasn’t standard of care. Sure, advocating for yourself could lead to an adversarial situation, but if you want to avoid mistakes and blind spots that can lead to your condition not improving or even worsening, I don’t see any other alternative.