Folic acid describes several forms of vitamin B9. It is critical to the formation and repair of DNA. It is critical during pregnancy as it assists the rapid growth of cells. It is also critical in the formation of red blood cells.
Folic acid deficiency is very rare, and is most common in pregnant women where it can cause complications of the pregnancy and, in some cases, nerve damage in the developing embryo. In adults deficiency can cause diarrhea, anemia, nerve damage, peripheral neuropathy and cognitive and behavioral problems. Meal replacement products (used by many dieters) often do not contain sufficient folic acid.
Folic acid is found in many foods including leafy vegetables, legumes, egg yolks, sunflower seeds and organ meats. It is regularly added to fortified breakfast cereals, bread and pasta as well.