A salt or ester of folic acid.
Folate, also called folic acid, folacin, or vitamin B9, is a water-soluble B-complex vitamin that is essential for human growth and development. It is made up of three components: para-aminobenzoic acid (PABA), glutamic acid, and pteridine. The latter two components explain the technical chemical name for folate: pteroylmonoglutamate. Because folate is one of the most chemically complex vitamins, it is also complicated in its interaction with your body. Most foods do not contain folate in the exact form described above, so enzymes inside your intestines must chemically alter food forms of folate in order for you to absorb it. Even when your body is operating at full efficiency, you can absorb only about 50% of the folate from your food.