5-MTHF is an active, tissue-ready form of folate.* It's an essential B vitamin that supports methylation.* Many individuals don't get sufficient 5-MTHF because they have intestinal or liver dysfunction or because of their genetic makeup.* A deficiency of folic acid has been linked to low-birth-weight infants and neural tube defects; adequate folic acid in healthful diets may reduce a woman’s risk of having a child with a neural tube defect.