Folsav

Folsav, commonly referred to as folate or folic acid, is a water-soluble B vitamin (vitamin B9) essential for human growth and cell function. Folate describes naturally occurring forms found in foods, while synthetic folic acid is added to fortified foods and used in dietary supplements. Synthetic folic acid is generally more readily absorbed than naturally occurring folates.

In metabolism, folate acts as a cofactor in one-carbon transfer reactions, enabling the synthesis of purines and thymidylate for DNA replication and repair, and supporting the remethylation of homocysteine to methionine. Because these processes are vital for rapidly dividing cells, adequate folate is especially important during pregnancy, infancy, and other growth periods.

Dietary sources include leafy greens (spinach, kale), legumes, liver, and citrus fruits, as well as fortified cereals and bread in many countries. General intake recommendations vary by authority and region, but guidelines for adults are typically around 400 µg per day; pregnant individuals are advised to aim for about 600 µg, and lactating people about 500 µg.

Deficiency can cause megaloblastic anemia, fatigue, pallor, and mouth ulcers, and in early pregnancy can increase the risk of neural tube defects in the fetus. Risk is higher with poor diet, alcoholism, malabsorption, certain medications, or increased requirements. Excessive folic acid from supplements can mask vitamin B12 deficiency and may interact with some drugs. The tolerable upper intake level for adults from fortified foods and supplements is 1,000 µg per day.

Public health guidelines often include folate supplementation for women planning pregnancy to reduce neural tube defect risk, and many countries require fortification of staple grains to improve population intake.