I came across an article in Medscape that descibes a research project involving folate. The research examined existing data.
Here is the link for the article. I hope it is available to everyone.
medscape.com/viewarticle/98...
Quoted here is the only part of the article that mentions B12 or treatment of B12 deficiency:
The investigators also assessed a negative control group of 236,610 individuals using cyanocobalamin during the study period. Cyanocobalamin is a form of vitamin B12 that is essential for metabolism, blood cell synthesis, and the nervous system. It does not contain folic acid and is commonly used to treat anemia.