Risk factors that should prompt consideration of B12 deficiency include advancing age (reduced stomach acid production), strict vegan or vegetarian diets, pernicious anaemia, gastrointestinal surgery (particularly gastric bypass or ileal resection), long-term use of certain medications (metformin, proton pump inhibitors, H2-receptor antagonists), nitrous oxide exposure (including recreational use), and conditions affecting the gut such as Crohn's disease or coeliac disease
One study found that after injecting high doses of vitamin B12 (specifically cyanocobalamin) into rodents, the B12 stayed in the bloodstream for a relatively short period, with a half-life ranging from 20 to 50 minutes
Reversible ADP-ribosylation of RNA
Also, see our article about supplements for peptic (stomach) ulcers
Chronic oscillating glucose challenges disarrange innate immune homeostasis to potentiate the variation of neutrophil-lymphocyte ratio in rats with or without hidden diabetes mellitus