B12 Complex Methylated Vitamin 1000mcg, Sublingual, Clean Igennus Igennus Healthcare Nutrition Efficacy of different routes of vitamin B12 supplementation for the treatment of patients with vitamin B12 deficiency: A systematic review and network meta analysis Irish Journal of Medical Science (1971 ) When would sublingual B12 supplements (as opposed to B12 tablets or injections) be indicated in a client with B12 deficiency? , The choice to use a sublingual B12 versus a tablet or injection is Effect of two different sublingual dosages of vitamin B12 on cobalamin nutritional status in vegans and vegetarians with a marginal deficiency: A randomized controlled trial ScienceDirect