Folic acid, together with vitamin B 12 and vitamin C, functions as a coenzyme essential to numerous biological processes including the metabolism and utilization of proteins. It is essential for DNA synthesis and proper cellular division. Folic acid is required during pregnancy because it is critical to the development of the fetus brain and nervous system. Folic acid deficiency is implicated in several birth defects including neural tube defects that affect the spinal cord and brain. It is concentrated in the spinal cord and extracellular fluids and is essential for brain function.
Folic acid is absorbed in the intestinal tract and is stored primarily in the liver.
Excess is excreted in the urine. Numerous factors may interfere with folic acid absorption including alcohol, sulfa drugs, smoking, and oral contraceptives. Celiac sprue and excessive vomiting or diarrhea can cause a deficiency of folic acid. High temperatures and light exposure can destroy folic acid. Folic acid supplementation may avert miscarriage.