how often should i have b12 injections When You Get a Vitamin Injection? B12 Injections: Who Should Get
Description
Endocrinology 136 , 49824989 (1995)

The standard diagnostic pathway includes a serum B12 blood test as the initial screening tool

Methylmalonic acid level (MMA)
If choosing between them, AOD-9604 has the stronger evidence base and regulatory standing

However, the impact of vitamin B-12 on the gut microbiome has not been established