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. B12 vitamin Store How to inject B12 in your arm What is the best B12 shot for someone with a C677T gene mutation who has reacted poorly to methyl B12 and oral supplements? B12 Injections vs Oral Supplements: Which Is Better for Energy and Deficiency?