I've seen some differing opinions in the veggie blogosphere about whether or not our dietary concerns should be treated as a choice or a need.
I can see both sides. Yes, it's a choice. Obviously, it's a conscious decision to go vegetarian or vegan, regardless of the reasons. For that reason, everything that you do to continue that lifestyle is a choice.
However, when the choice is so personal, and can have such strong effects on health, it's also sort of a need. Like I mentioned when I talked about my ER visit, if your system isn't used to animal products, eating them can make you sick. Even if it isn't so extreme, it can still lead to an upset stomach or headache, and at best that's highly unpleasant.
So I guess my conclusion is that it's a choice that should be treated like a need. I opted to make certain changes to my diet, but for my own health I need them respected and heeded.