Water-soluble vitamin B6 is widely present in many foods, including meat, fish, nuts, beans, grains, fruits and vegetables. Additionally, B6 is present in many multivitamin preparations for adults and children and added to foods as a supplement to breakfast foods, power bars, and powders. There are several active compounds or vitamers which fall under the generic B6. These include (1) pyridoxine an alcohol, (2) pyridoxal an aldehyde, (3) pyridoxamine which differs from the first two with an amine group, and (4) a 2,5' phosphate esters. The major esters are the active coenzyme form and are pyridoxal 5'phosphate(PLP) and pyridoxamine 5'phosphate(PMP). The major form of B6 in meats are the esters, and the major plant source is pyridoxine, which is less bioavailable. Pyridoxine is the most common form found in multivitamins. As a coenzyme, B6 is involved as a cofactor in over 100 enzyme reactions including amino acid metabolism, particularly homocysteine; carbohydrate metabolism, including gluconeogenesis and glycogenolysis; and lipid metabolism. B6 has a role in cognitive development thru neurotransmitter synthesis, immune function with interleukin-2 production, and hemoglobin formation. Fetal brain development requires adequate B6, and this continues throughout infancy. Vitamin B6 recommendations are made in accordance with age and life stage with pregnancy and breastfeeding involving the highest recommended daily allowance.
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