If you follow a vegan diet, lack B12-rich food, or suffer from health conditions like B12 deficiency, which happens when a person cannot absorb it properly, then you may experience b12 deficiency
But oral versus injectable is not a single, simple comparison, because the pills are not all the same and the honest answer to should I take the shot or the pill depends on which pill, and on what you are trying to achieve
Research suggests that significant weight loss over a short period may increase the risk of temporary hair shedding, though individual responses vary considerably
This strategy preserves weight loss gains while your metabolism stabilizes
Shen X, Chen Y, Tang Y, Lu P, Liu M, Mao T, et al
and (6) cell cycle and DNA repair pathways (e.g., DNA damage response, cell cycle regulation)