places to get b12 injections in fayetteville ar How Give a Injection: Step-By-Step Instructions Vitamin B12 Injection Sites: All

Description

Ministry of Health

Massironi S, Zilli A, Elvevi A, Invernizzi P

not present in plants Daily requirement: ~ 23 g/day Body stores: 25 mg , mostly in the liver (sufficient for 25 years) Absorption Pathway : In the mouth/stomach: B12 is protein-bound in food Stomach acid and pepsin release B12 from food proteins B12 binds to haptocorrin (also called R-binder or transcobalamin I) secreted by salivary glands and gastric mucosa In the small intestine : In the duodenum , pancreatic proteases degrade haptocorrin Free B12 then binds to intrinsic factor (IF) , a glycoprotein secreted by gastric parietal cells The B12IF complex travels to the terminal ileum , where it binds to cubilin receptors and is absorbed via receptor-mediated endocytosis 1 In the enterocyte and bloodstream: Inside enterocytes, B12 dissociates from IF It binds to transcobalamin II (TCII) for systemic transport Only B12TCII complex (called holotranscobalamin ) is biologically active and taken up by tissues Storage and transport: B12 is stored in the liver (main site), but also in muscle Transcobalamin II transports active B12 to tissues