Vitamin B12 (also called cobalamin) deficiency affects roughly 6% of adults aged 70+ years and is a concern frequently attributable to gastric atrophy that leads to malabsorption. B12 is found primarily in animal products bound to the protein and must be freed by the digestive action of our stomach acid and enzymes. Once freed from the protein, B12 is immediately bound to an R protein within the gastric juice that protects it from bacterial use. Upon entering the small intestine, the B12 is released from the R protein and binds to intrinsic factor (IF) that was synthesized within the stomach but escapes digestion. This B12-IF complex travels through the small intestine to interact with receptors that allow for the absorption of B12. Gastric atrophy affects the early steps of this process by limiting protein digestion and/or the production of IF. Full-blown B12 deficiency leads to numerous neurologic and cognitive disturbances as...
