What is folic acid?

Folic acid, also known as vitamin B9, is a water-soluble vitamin in the B-complex family that plays a crucial role in cell division, DNA synthesis, blood formation, and tissue growth. In its natural form—the form found in foods—it is called folate, while folic acid is the synthetic, particularly stable form used in supplements and fortified foods.

The name comes from the Latin word folium (leaf), as folate was first discovered in green leafy vegetables. Good natural sources include spinach, broccoli, kale, asparagus, legumes, oranges, whole grains, and liver.

Folic acid is essential for growth, the formation of new cells, and the development of the nervous system—particularly during pregnancy, as it supports neural tube formation in the unborn child. A deficiency can have serious consequences, which is why folic acid is considered one of the most important vitamins.

How does folic acid work?

After it is absorbed, folic acid is converted into the active form tetrahydrofolate (THF), which acts as a coenzyme in a wide range of vital processes.

Cell division and DNA synthesis:
Folate is necessary for the formation of nucleic acids (DNA and RNA)—the genetic building blocks of every cell. Without enough folic acid, the body cannot form new cells, which is especially critical during periods of rapid growth, such as pregnancy, childhood, or tissue regeneration.

Blood formation:
Together with vitamin B12, folic acid is essential for the maturation of red blood cells. A deficiency causes a condition called megaloblastic anemia, in which large, dysfunctional blood cells form, leading to fatigue, paleness, and difficulty concentrating.

Nervous system protection and homocysteine breakdown:
Together with vitamins B6 and B12, folic acid lowers levels of the amino acid homocysteine, which can damage blood vessel walls when present in excess and contribute to cardiovascular disease. In this way, it indirectly supports heart health and blood vessel elasticity.

Pregnancy and development:
Adequate folic acid intake during pregnancy is essential for embryonic development. It reduces the risk of serious birth defects such as neural tube defects (e.g., spina bifida) by up to 70%. That is why women planning to have a child are advised to take 400 µg of folic acid daily starting before conception.

Skin, hair, and tissue:
Because folic acid promotes cell division and regeneration, it also has a positive effect on skin renewal, hair growth, and wound healing.

Benefits of folic acid

  • Supports cell division and the growth of new cells

  • Promotes DNA and RNA synthesis

  • Supports red blood cell formation and helps prevent anemia

  • Protects the heart and blood vessels by regulating homocysteine

  • Essential for a healthy pregnancy and the development of the fetal nervous system

  • Supports skin, hair, and tissue regeneration

  • Promotes mental performance and concentration

Possible side effects and interactions

Folic acid is generally very well tolerated. Because it is water-soluble, excess amounts are excreted in the urine. However, very high doses (over 1000 µg per day) can mask a vitamin B12 deficiency, as folic acid corrects the anemia but does not prevent neurological damage. Therefore, it is advisable to take vitamin B12 along with higher doses.

Folate deficiency can be caused by an unbalanced diet, alcohol, stress, certain medications (e.g., birth control pills, methotrexate, antiepileptic drugs), or increased rates of cell division.

Conclusion

Folic acid is an essential vitamin for growth, blood formation, and cell health. It ensures normal cell division, protects the cardiovascular system, and is essential for a healthy pregnancy. Since it is often lacking in many modern diets, women of childbearing age, older adults, and people experiencing high levels of stress may benefit in particular from targeted folic acid intake—ideally combined with vitamins B12 and B6 to support cells, blood, and nerves as a whole.

Sources

  1. Bailey LB, Gregory JF. (1999): Folate metabolism and requirements. J Nutr, 129(4), 779–782.

  2. Lucock M. (2000): Folic acid: nutritional biochemistry, molecular biology, and role in disease processes. Mol Genet Metab, 71(1–2), 121–138.

  3. Blom HJ, Shaw GM, den Heijer M, Finnell RH. (2006): Neural tube defects and folate: case far from closed. Nat Rev Neurosci, 7(9), 724–731.

  4. Selhub J. (2002): Folate, vitamin B12 and vitamin B6 and one carbon metabolism. J Nutr Health Aging, 6(1), 39–42.