Co-Enzyme B Vitamin Metabolically Active Folate Superior Bioavailability Quatrefolic A Dietary Supplement Vegetarian/Vegan Vitamins Family Owned Since 1968 GMP Quality Assured Methylfolate is the biologically active, naturally occurring form of folate that is used for fundamental body functions like normal cell division and the synthesis of neurotransmitters and DNA. Unlike regular folic acid, methylfolate has been shown to penetrate the blood-brain barrier, where it helps support neurological health. Quatrefolic is a patented form of methylfolate that has demonstrated bioavailability superior to that of folate from dietary sources.