folát

Folát, or folate, refers to a group of compounds that are forms of vitamin B9. Natural folates occur in foods as polyglutamates, while folic acid is the synthetic, oxidized form used in supplements and food fortification. In the body, folic acid is reduced and methylated to become 5-methyltetrahydrofolate (5-MTHF), the main circulating form that participates in one-carbon metabolism.

Function and metabolism: Folate coenzymes are essential for DNA synthesis and repair, and for the metabolism of amino acids. They donate one-carbon units needed for the production of purines and thymidine, a building block of DNA. Folate also participates in the remethylation of homocysteine to methionine, linking it to methylation reactions important for gene expression and other processes.

Dietary sources and intake: Rich natural sources include leafy greens, legumes, eggs, and liver. Many countries fortify grain products with folic acid to reduce neural tube defects. For adults, a typical reference intake is around 400 micrograms of dietary folate equivalents (DFE) per day; pregnant individuals are advised higher intakes (about 600 µg DFE). The tolerable upper intake level for synthetic folic acid from supplements and fortified foods is about 1,000 µg per day.

Deficiency and health effects: Folate deficiency can cause megaloblastic anemia and impaired DNA synthesis, with symptoms such as fatigue and glossitis. In pregnancy, inadequate folate increases the risk of neural tube defects in the fetus. Deficiency is more common in people with poor intake, malabsorption, alcohol use disorder, certain medications (for example methotrexate), or advanced age. Blood tests may assess serum or red blood cell folate levels; elevated homocysteine can indicate folate insufficiency.

Excess and interactions: Most people tolerate folate well, but high intakes of synthetic folic acid can mask vitamin B12 deficiency and may interact with certain medications. Folinic acid is a related supplement used in specific medical contexts, such as mitigating antifolate drug effects.