[7] In the less acidic environment of the small intestine, pancreatic enzymes digest the glycoprotein carrier and vitamin B12 can then bind to intrinsic factor.

In pigs it is obtained from the pylorus and beginning of the duodenum;[12] in human beings it is present in the fundus and body of the stomach.

[15] Atrophic gastritis can also cause intrinsic factor deficiency and anemia through damage to the parietal cells of the stomach wall.

[16] Pancreatic exocrine insufficiency can interfere with normal dissociation of vitamin B12 from its binding proteins in the small intestine, preventing its absorption via the intrinsic factor complex.

[citation needed] Mutations in the GIF gene are responsible for a rare inheritable disease called intrinsic factor deficiency[18] which results in malabsorption of vitamin B12.