B-12 mcg amount??
I think it varies greatly from person to person. I take one 500 mcg B-12 (sublingual) every day, and my B12 level is very high - way over the normal range, which is fine, I understand. Anyway, this is what I've always taken and my labs have always shown a high level for B12. So I would say you need to go by what your lab work tells you is needed.
Carlita