Licensed 503A compounding pharmacies can fill prescriptions from clinicians in most states today

Common symptoms that may indicate conditions associated with elevated MMA (B12 deficiency): Fatigue: Persistent tiredness and weakness, may be related to impaired energy metabolism and potential anemia from inadequate red blood cell production Neurological symptoms: Numbness and tingling in extremities (paresthesia), may be connected to myelin sheath damage in peripheral nerves due to B12 deficiency Cognitive changes: Memory issues, confusion, or difficulty concentrating, could be associated with impaired brain function and potential neurotransmitter imbalances Mood disturbances: Depression, irritability, or mood swings, may be linked to B12s role in neurotransmitter synthesis and nervous system health Oral symptoms: Inflamed, smooth, red tongue (glossitis) or mouth ulcers, may reflect rapid cell turnover in oral tissues that depends on adequate B12 Balance problems: Difficulty with coordination or unsteady gait, may be related to neurological damage affecting proprioception and motor control Anemia symptoms: Pale skin, shortness of breath, heart palpitations, could result from megaloblastic anemia due to impaired red blood cell maturation Its important to understand that many factors besides B12 deficiency can cause these symptoms

The authors do cite a study associating benzene exposure with cardiac risk among 210 clinic patients with cardiovascular risk (Abplanalp et al., 2017)
The treatment was 10 g or 50 g of B12 daily