Glossary. Intrinsic factor is a glycoprotein secreted by parietal (humans) or chief (rodents) cells of the gastric mucosa. In humans, it has an important role in the absorption of vitamin B12 (cobalamin) in the intestine, and failure to produce or utilize intrinsic factor results in the condition pernicious anemia.Dietary vitamin B 12 is released from ingested proteins in the stomach through the action of pepsin and acid.n humans, it has an important role in the absorption of vitamin B12 (cobalamin) in the intestine, and failure to produce or utilize intrinsic factor results in the condition pernicious anemia. Dietary vitamin B 12 is released from ingested proteins in the stomach through the action of pepsin and acid.