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

Folic acid is synthetically produced, and used in fortified foods and supplements on the theory that it is converted into folate.[9] 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.

Vitamin B9 is essential for numerous bodily functions. Humans cannot synthesize folates de novo; therefore, folic acid has to be supplied through the diet to meet their daily requirements. The human body needs folate to synthesize DNA, repair DNA, and methylate DNA as well as to act as a cofactor in certain biological reactions. It is especially important in aiding rapid cell division and growth, such as in infancy and pregnancy. Children and adults both require folate to produce healthy red blood cells and prevent anemia.