There are lots of rules in some facilities regarding bringing food from home to patients.
IF the patient ends up getting sick on some food--from anything to food poisoning to the fact that some food doesn't keep well, it is a compromise to the patient.
As well as if it is a food that say the room mate is allergic to.....it is like the schools
that either require a student to NOT bring in a peanut butter sandwich OR require students to purchase lunch and are not allowed to bring in their own lunch.
There are some behavioral health patients that intentionally ask for and eat food that they may have a skin reaction to. Then they can manifest inappropriate behaviors ie: skin scratching. Even more that well meaning (or not) relatives, friends are bringing food that has been "supplemented" with just about anything. Further, there are SI patients who will ask for a peanut butter pie....in an attempt to give themselves a fatal reaction.
You just don't know. And taking home brought food out of the equation can at least give some control over what your patient is consuming.
Registered dieticians go through some significant education and the registry test is not to be believed in its complexity. Nurses know the basics, however, why not let the RD's do their thing. If a patient has an issue, then by all means you can facilitate a meeting with the RD and the patient.