oral vs injection b12 Frontiers B12 Injection vs. Oral Supplements:

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However, several reports highlight that while generally safe, these injections can sometimes cause adverse effects, most notably hypersensitivity and anaphylactic reactions

doi: 10.1093/jn/nxy140, [DOI] [PubMed] [Google Scholar] 72.Yi X, Yang Y, Li T, Li M, Yao T, Hu G, et al

Glutathione is a naturally produced tripeptide, composed of glycine, cysteine, and glutamic acid

I think they have some benefit, but youre not going to see massive results and you definitely arent going to reverse 20 years of ageing with some light bulbs