Feeling Tired All the Time? It Might Be a Vitamin B12 Deficiency Fusion HealthCare Do you follow a vegetarian diet? Did you know that vitamin b12 is mainly present in animal based products so those following a strict plant based are more likely to be deficient in vitamin Vitamin B12 Injection Dose for Adults: 7 Key Facts on Dosage & Frequency Liv Hospital 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.