GLOSSARY

Vitamin B12 Absorption is a multistep process involving release from food, binding proteins and intestinal uptake; intake is not equal to absorbed quantity.

Food-bound B12 must first be released, then normally uses gastric intrinsic factor and absorption in the terminal small intestine. A small fraction can also enter by an independent pathway. Package amount is therefore not the absorbed amount, and gastric or ileal problems can impair status despite adequate food. These mechanisms help explain why dietary and medical correction strategies can differ.

Animal foods and genuinely fortified products are dependable B12 sources. Fermented plant foods or algae should not be assumed reliable without verified content and forms. Vegan diets need a planned fortified-food or supplement source. Body stores can delay deficiency, so having no symptoms in the first months does not guarantee long-term adequacy or make regular provision unnecessary.

Cobalamin names the B12 family. Methylcobalamin and adenosylcobalamin are coenzyme forms; cyano- and hydroxocobalamin can be converted. Active branding does not establish superiority for everyone. Route, amount and deficiency cause matter, and oral products and injectable medicines are not interchangeable solely because their names are related; clinical circumstances govern their use.