folic acid (FA) /fō″lik, fol″ik/ , a yellow crystalline water-soluble vitamin essential for cell growth and reproduction. It functions as a coenzyme with vitamins B12 and C in the metabolism and use of proteins and in the formation of nucleic acids and heme for hemoglobin. Deficiency results in poor growth, graying of hair, glossitis, stomatitis, GI lesions, and diarrhea, and it may lead to megaloblastic anemia. Deficiency is caused by inadequate dietary intake of the vitamin, malabsorption, metabolic abnormalities, or drug-nutrient interactions. Need for folic acid increases in pregnancy, infancy, and periods of stress. A daily intake of 400 mg before conception and during early pregnancy has been found to lower the risk of fetal neural tube defects. Rich dietary sources include spinach and other green leafy vegetables, liver, kidney, asparagus, lima beans, nuts, orange juice, and whole-grain cereals. It is both heat- and light-labile, and considerable loss of the vitamin occurs during cooking and when it has been stored for a long period. Also called folacin, pteroylglutamic acid, vitamin B9.
