Unlike oral B12 tablets, B12 injections are rapidly absorbed by the body immediately after administration and do not pass through the digestive system
doi:10.1152/ajpendo.2000.279.3.E501 Ng FM, Sun J, Sharma L, Libinaka R, Jiang WJ, Gianello R
Ethics statement The studies involving humans were approved by the Institutional Review Board of the Galen Academy, based in So Paulo, Brazil, approved the data collection and analysis for this study (approval number 7.293.366, CAEE: 85144924.8.0000.9887)
Effects of AOD-9604 on adipose tissue and metabolic function: A clinical review
They can also recommend alternative supplementation methods, such as oral supplements or patches, if injections are not necessary or appropriate for your situation
They are not approved by the FDA for human therapeutic use