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==What is Vitamin B12 (Cobalamin)?==

==What is Vitamin B12 (Cobalamin)?==

'''Vitamin B₁₂''', is an '''essential cobalt-containing water-soluble vitamin'''. '''Cobalamin''' is the preferred name for the family of vitamins known as vitamin B₁₂. It is synthesised by bacteria in the large intestine of cats and dogs, however the site of synthesis is caudal to the site of absorption making cobalamin a '''required dietary nutrient'''<ref name="NRC">National Research Council (NRC). Vitamins. In Nutrient Requirements for Dogs and Cats. 2006 Washington, DC: National Academies Press p.225-227.</ref>. Cobalamin in the diet is bound to protein as either methylcobalamin or adenosylcobalamin and must be cleaved and subsequently bound to an endogenously synthesised glycoprotein called intrinsic factor (IF). Intrinsic factor is produced in the stomach and pancreas of dogs<ref>Batt RM and Horadagoda NU. Gastric and pancreatic intrinsic factor-mediated absorption of cobalamin in the dog.  Am J Physiol 1989;257:G344-G349.</ref>, but exclusively in the pancreas in cats<ref>Fyfe JC. Feline intrinsic factor (IF) is pancreatitic origin and mediates ileal cobalamin (CBL) absorption.  JVIM 1993;7:133.</ref>. Mucosal receptors for IF are found in highest concentration the ileum of dogs and cats. After binding of IF, cobalamin is dissociated and absorbed by the enterocyte, where it is then primarily bound to another glycoprotein (transcobalamin II) for transport in the blood<ref name="NRC"/>. Cobalamin is primarily stored in the liver and freely excreted through the renal tubules.

'''Vitamin B₁₂''', is an '''essential cobalt-containing water-soluble vitamin'''. '''Cobalamin''' is the preferred name for the family of vitamins known as vitamin B₁₂. It is synthesised by bacteria in the large intestine of cats and dogs, however the site of synthesis is caudal to the site of absorption making cobalamin a '''required dietary nutrient'''<ref name="NRC">National Research Council (NRC). Vitamins. In Nutrient Requirements for Dogs and Cats. 2006 Washington, DC: National Academies Press p.225-227.</ref>. Cobalamin in the diet is bound to protein as either methylcobalamin or adenosylcobalamin and must be cleaved and subsequently bound to an endogenously synthesised glycoprotein called intrinsic factor (IF). Intrinsic factor is produced in the stomach and pancreas of dogs<ref>Batt RM and Horadagoda NU. Gastric and pancreatic intrinsic factor-mediated absorption of cobalamin in the dog.  Am J Physiol 1989;257:G344-G349.</ref>, but exclusively in the pancreas in cats<ref>Fyfe JC. Feline intrinsic factor (IF) is pancreatitic origin and mediates ileal cobalamin (CBL) absorption.  JVIM 1993;7:133.</ref>. Mucosal receptors for IF are found in highest concentration the ileum of dogs and cats. After binding of IF, cobalamin is dissociated and absorbed by the enterocyte, where it is then primarily bound to another glycoprotein (transcobalamin II) for transport in the blood<ref name="NRC"/>. Cobalamin is primarily stored in the liver and freely excreted through the renal tubules.