Dear I.F.: The DV (a replacement for what we used to call the recommended daily allowance, or RDA) for vitamin B12 is 2.4 mcg ...

However, the neurologist told me to take 2,000 mcg of B12 daily. My multivitamin ... for vitamin B12 is 2.4 mcg. (There are 1,000 micrograms in a ... or they would prescribe B12 injections.