How serious is the MAO-A finding really?+ Serious enough to change who should use it, not serious enough to rule it out for everyone
Mechanistic case, trial data, and the open question
The one real argument for injecting is bypassing first-pass metabolism, and the strength of that argument depends entirely on which bioavailability study you believe (3.5% in mice versus 38.4% in rats)
Because the injection allows for direct absorption, the effects are typically felt much more quickly than with oral supplements
Clinical trials involving approximately 900 participants found that the adverse event profile was indistinguishable from placebo for most parameters
A balanced diet rich in vegetables, fruits, whole grains, and protein can enhance overall health and support Vitamin B12 absorption