injections of b12 are given in the treatment of Compounded Hydroxocobalamin (Vitamin B12) Injection Vitamin B12 Injection: Uses, Benefits,

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If your body does not have sufficient B12, then it cannot make energy and so therefore you are weak, tired, or unfocused

Ok, so these are interesting points but please add this into the mix for future answers: The NICE Guideline clearly states that there is insufficient research why some people need more frequent injections than others and that an 8- or 12- weekly schedule does not work for everyone and some may need more frequently

In dietinduced obese mice, NNMTi treatment significantly reduced liver weight, liver volume, and hepatic triglyceride levels, alleviated hepatic steatosis and inflammatory infiltration, downregulated inflammatory factors (such as TNF and IL6) and lipogenic genes (such as FAS), and upregulated lipolytic genes (such as ATGL) in the liver

doi:10.1016/j.ejmg.2019.103713