I don't think it would be a rude gesture, but that is just me. I'm no Dr. and I can tell you your B12 is low and needs treated. My Dr. treats anything below 350 and I still feel that is even low. Some other countries say 600 is low. I guess you could do the book thing and maybe tell her why and if she takes it bad then she does. Obviously you are only doing it for her and hoping for something positive to come out of it. Even with a b12 of 228 you are close to low, why wouldn't she treat it? Some Dr's are better at other things, maybe this is just something she isn't good with and needs it.
If she took the book and read it, not only would it help her but it would help all her patients too.
In the meantime go to the store and get yourself some sublingual B12. The ones I found only came in 500. I take 1000 a day and they dissolve right under your tongue. I was able to bring up my b12 about 500 points in a month. You can't overdose on B12 so you could even take more if you wanted.