Vitamin B12 Oral vs Injection B12 Injections vs. Oral Supplements: Which Is Better? Recently I have been asked a lot for VitaminB12 injections. I initially decided not to offer vitamin B12 injections as some literature showed that the efficacy of oral vitamin B12 was the Understanding The Benefits of B12 Shots for Weight Loss Vitamin B12 injections deliver high doses of this essential vitamin directly into your bloodstream for better absorption than oral supplements to boost energy, support red blood cell production and maintain nerve function. What is an acceptable oral vitamin B12 (cobalamin) supplement alternative to intramuscular injections for a patient with severely low vitamin B12 levels, particularly those with malabsorption or pernicious anemia?