Folic acid, the oxidized from of vitamin B9, and its derivative, tetrahydrofolate, are water-soluble vitamins commonly known as folates. The term folate originates from the Latin word folium, which means leaf. In fact, folates are found in substantial amounts in green leafy vegetables. Folates are also obtained from fruits, grain, yeast, liver, nuts, and dairy products. Folate is easily inactivated by heat, light, and acid and, therefore, can be lost from foods during storage, preparation, or cooking. However, fermentation with yeast can increase folate content in breads to levels greater than the original flour. 1,4

The structure of the folic acid is best described as a complex of individual compounds. A pterin nucleus is bound to para-aminobenzoic acid (PABA) to form pteroic acid. Glutamic acid is linked to the PABA portion of pteroic acid, forming folate, or pteroylmonoglutamic acid or pteroylmonoglutamate. Although all three components can be synthesized separately in the human body, humans lack the enzyme that condenses them to form folate. 3

Folate/folic acid is vital in transferring of single carbon units in the human body, which is essential for a wide range of biochemical reactions inclding DNA and RNA synthesis, amino acid metabolism, and protein synthesis. Since folate and vitamin B12 are interdependent, additional supplementation of vitamin B12 may enhance the utilization and biological effects of folic acid. 4

Folate is different from folic acid. Folate is the natural compound found in food, while folic acid is a synthetic form used in supplements and food fortification. Folic acid is more potent than folate because it is more easily absorbed in the intestine. In the blood, folate circulates as monoglutamate.

The impaired folate-dependent cellular metabolic mechanisms can lead to several pathologic conditions, including megaloblastic macrocytic anemia, homocysteinemea, cardiovascular disease, embryonic defects (neural tube defects), congenital heart defects, psychosis, and mental deterioration. 1,3

There are concerns that mandatory fortification of flour with folic acid might have adverse effects on neurological function in people aged 65 years and over with vitamin B12 deficiency. Clinical signs of vitamin B12 deficiency are anemia and/or neurological disorder. Treatment with folic acid will mask anemia and therefore delay the diagnosis of vitamin B12 deficiency, which can lead to irreversible degeneration of the spinal cord. 2 Folic acid supplements appear to increase the risk for polyps. 5

  1. Gerald Litwack. Folic Acid and Folates.
  2. Great Britain: Scientific Advisory Committee on Nutrition, Great Britain: Department of Health. Folate and Disease Prevention
  3. Denis M. Medeiros, Robert E. C. Wildman. Advanced Human Nutrition.
  4. Victor R. Preedy. Handbook of Behavior, Food and Nutrition, Volume 1.
  5. Diet and Cancer