vitamin B-12
elevated homocysteine levels
increased risk for heart attack and stroke
treating B12 deficiency
inject directly into body, nasal gel
storage
liver
methylmalonyl mutase
metabolism of fatty acids with an odd number of carbons
formation of methionine from homocysteine
methyl donor
UL
none
foods
organ meats, fortified foods, meat, fish, poultry, dairy products
deficiency
pernicious anemia, neurological complications, elevated plasma homocysteine concentrations
B-12 in mouth
salivary glands produce R protein
B-12 in liver
stored
B-12 in ileum
vit/intrinsic factor absorbed into blood and binds to transport protein transcobalomin II
transport
blood transport protein transcobalamin II
absorption
bound to protein, HCl and pepsin in gastric juices release vitamin B-12, binds to R-protein, small intestine pancreatic protease enzymes release vitamin B-12 from R-protein
functions
formation of amino acid methionine, enzyme methylmalonyl mutase
B-12 in stomach
1. HCl and pepsin release vitamin B-12 bound to protein in food 2. free vitamin binds with R-protein 3. parietal cells secrete intrinsic factor
B-12 in small intestine
1. trypsin from pancreas releases 2. vit links with intrinsic factor
absorption location and %
50% in the ileum