There is a really good Dr. here in N.Y. he combines modern medicne and holistic old world. He has a talk radio show that I happen to be listening to so I decided to call and see what he thought about b12. He said anyone who's level is under 500, and has symptoms, should automatically be given shots with out another thought about it. If you want to check him out he has a web site. drhoffman.com He has a center in N.Y. they also sell lots of good vitamins and supplements.