B12 , Folic Acid and Iron

Vitamin B12
• Most chemically complex of all vitamins.
• Foods that come from animals, including fish and shellfish, meat (especially liver), poultry, eggs, milk, and milk products
• Fx- DNA synthesis and regulation / Fatty acid synthesis and energy production / Folate.
• Cyanocobalamin – synthetic form, supplements and food addictive. Body converted to methylcobalamin and adenosylcobalmin leaving cyanide behind. Hydroxycobalamin is the another form from bacteria and it’s more epx than cyanocobalamin cause it’s easier converted to active forms.
• Starts absorption in the mouth where unbound B12 and acid in stomach where protein bounded B12 is digested and freed by binding to intrinsic factor. IF/B12 complex is recognized by ileal receptors and transported to portal circulation and stored in liver.
• Two enzymatic reaction dependent of B12[co-factor]

• Methionine is required for lipid synthesis for myelin synthesis.
• Pernicious anemia – lack of intrinsic factor that would cause incapable of B12 absorption.
• Usually B12 deficiency is due to genetic factors which limit the absorption.
Folic Acid [B9]
• Both animal and plants –green leafy vegetables, legumes, yeast, fish
• Active forms – tetrahydrofolate and dihydrofolic acid.
• Fx – DNA synthesis and repair / cofactor involving folate reaction.
• Folate deficiency causes neural tube defects in 1st trimester [spina bifida, anencephaly] / cancer development
Both B9 and B12
• Deficiency causes elevated Homocysteine
o Homocysteine is an amino acid in the blood. Too much of it is related to a higher risk of coronary heart disease, stroke and peripheral vascular disease
Mineral: Iron
• Heme and non heme iron. Heme from animals such as red meat, fish and poultry. Non heme from plants such as lentils and beans. Heme iron is absorbed better.
• Fx
o Both an electron donor and acceptor.

o Used to produce Heme. Heme+globulin become hemoglobin order to transport oxygen from the lungs to the tissues and to export carbon dioxide back to the lungs. Iron is also an essential component of myoglobin to store and diffuse oxygen in muscle cells.
o Bacterial protection by limiting the storage of irons in the body. Iron is important for the survival of the bacteria. Hemochromatosis individuals are more susceptible to infections.
• Body stores 3-4g iron in bod. Men got more stores of iron than women due to the heavy usage of women during menstruation, pregnancy and lactation.
• Lose 1-1.5mg perday by sweating and shedding cells from skin and mucosal lining of GIT.
• Iron absorption

o Ferric Fe3+ to Ferrous Fe2+ before can be absorbed. [ferric reductase enzyme] at brush border of enterocyte.
o Body stores iron in the form of Ferritin. Ferritin is then bounded to transferin through a pore called ferroportin to be carried to parts of the body. Mostly to the liver hepatocytes for storage, bone marrow and spleen.