Folic acid

Folic acid or folate is a B vitamin. It is also referred to as vitamin M,vitamin B₉,vitamin B_c (or folacin), pteroyl-L-glutamic acid, and pteroyl-L-glutamate.

Food supplement manufacturers often use the term folate for something different from "pure" folic acid: in chemistry, folate refers to the deprotonated ion, and folic acid to the neutral molecule—which both coexist in water. The International Union of Pure and Applied Chemistry and the International Union of Biochemistry and Molecular Biology state that folate and folic acid are the preferred synonyms for pteroylglutamate and pteroylglutamic acid, respectively.

Folate indicates a collection of "folates" that is not chemically well-characterized, including other members of the family of pteroylglutamates, or mixtures of them, having various levels of reduction of the pteridine ring, one-carbon substitutions and different numbers of glutamate residues.

Folic acid is synthetically produced, and used in fortified foods and supplements on the theory that it is converted into folate. However, folic acid is a synthetic oxidized form, not significantly found in fresh natural foods. To be used it must be converted to tetrahydrofolate (tetrahydrofolic acid) by dihydrofolate reductase (DHFR). Increasing evidence suggests that this process may be slow in humans.