Methyl Folate ((6S)-5-methyltetrahydrofolate or (6S)-5-MTHF) is the most biologically active form of folate.* Quatrefolic® is the 4th generation development in folate delivery. With certain inherited errors in metabolism and physiologic stresses, the transformation of synthetic folic acid into the active form of folate is inadequate.* Unlike folic acid, 5-MTHF can cross the blood-brain barrier and does not mask pernicious anemia.*