--is advised, at the very least, to consider B12 supplementation, as the reduction in acid concentration these engender makes it much harder to break B12 out of food, which gets harder with age anyway.

I also think, since acid is necessary for protein to be released from foods, that one should try to monitor this and eat a somewhat lower carb, higher protein diet. This doesn't have to necessarily come from animal products--proper combination of grains and legumes/vegetables can provide it. There seems to be more difficulty breaking protein out of animal products with low stomach acid.