Folic acid, or folate, is a B vitamin that must be derived from either dietary sources or via supplementation. Folate is necessary for a biochemical process in the body called "methylation" or "one-carbon metabolism." This process does not work adequately in a significant number of individuals who have a genetic polymorphism, and it may contribute to a host of different concerns, including neural tube defects, depression, and reduction in red blood cell production. When the body absorbs folate, it goes through a series of biochemical conversions to become the active form l‑5‑methyltetrahydrofolate. If an individual is unable to convert the folate properly, they can end up with a deficiency, even though they are eating foods containing folate. Folate is found in leafy green vegetables, legumes, beans, liver, yeast, and citrus fruits.