FOLIC ACID

also called Pteroylglutamic Acid, Folate, or Folacin, a vitamin of the B complex that is essential in animal metabolism and that is needed by bacteria as a growth factor. It is required by all higher animals studied, but the requirement is difficult to demonstrate in some animals because the vitamin is synthesized by bacteria contained in an animal's intestinal tract. In humans and other mammals, folic acid is necessary for the synthesis of nucleic acids and the formation of heme, the pigmented, iron-carrying component of the hemoglobin in red blood cells. The vitamin has a wide variety of sources in the human diet, including leafy green vegetables, citrus fruits, cereals, beans, poultry, and egg yolks. A deficient intake of folic acid can impair the maturation of young red blood cells, resulting in folic-acid-deficiency anemia. Pregnant women with an insufficient intake of folic acid are more likely to give birth prematurely or to deliver babies with low birth weight or with neural tube defects. The sulfa drugs are thought to achieve their antimicrobial effects by interfering with the production of folic acid within bacteria. See also folic-acid-deficiency anemia; tropical sprue.