3 amino acids in glutathione 5 Route of synthesis of (GSH) involving three Glutathione distribution in subcellular compartments.

It consists of three amino acidsglutamine, cysteine, and glycineand plays a critical role in protecting cells from oxidative damage

Levels were lowest in regions with the highest rates of maternal vitamin B 12 deficiency

Yet, if your diet isnt healthy enough or if your body has an underlying problem, it can not absorb enough B12, which might cause health issues

Eriksson CJ

and since the schilling test is no longer available the exact cause of the low b12 which is not technically the same thing as pernicious anaemia not caused by diet is probably unknown so 1mg cyancobalamin will probably help someone who can produce some Intrinsic Factor that they can absorb enough from a oral supplement but just not from food but to presume it will help everyone is absurd