This water-soluble vitamin supports all kinds of bodily functions, including red blood cell formation and neurological function
Neomycin, colchicine, para-aminosalicylic acid, or excessive alcohol intake longer than two weeks may cause malabsorption of vitamin B12. Chloramphenicol and other drugs having bone marrow suppressant properties may cause a lack of therapeutic response to vitamin B12
Because injections do not rely on stomach acid or intrinsic factor, a much larger and more reliable share of the dose reaches your bloodstream, even when gut absorption is poor
But as time goes by and you get the hang of it, you can start doing it independently
While spirulina, dried nori, barley grass and most other seaweeds contain some B12 (dirt even contains some), consuming these foods hasnt been shown to provide enough B12 to vegans