b12 injections for men | Hampton Roads Vitamin B12 Injections: Good or

Takahashi R, Kanda T, Komatsu M, Itoh T, Minakuchi H, Urai H, Kuroita T, Shigaki S, Tsukamoto T, Higuchi N, Ikeda M, Yamanaka R, Yoshimura N, Ono T, Yukioka H, Hasegawa K, Tokuyama H, Wakino S, Itoh H (2022) The significance of NAD + metabolites and nicotinamide N -methyltransferase in chronic kidney disease

Also, high-dose B12 has been linked to acneiform eruptions in some case reports and reviews (Bahbouhi et al., 2023) as described in the PubMed record

Many people do but if you have a digestive condition, low stomach acid or any gut absorption issue, very little of an oral supplement will actually be absorbed regardless of the dose