Folic acid is a B vitamin. It is involved in very important cellular reactions. A frank deficiency of folic acid can cause macrocytic anemia. Inadequate intake is related to birth defects, premature births, cervical dysplasia, and many different cancers including cervical and breast. Inadequate folic acid also causes the buildup of an amino acid in the blood called homocysteine. High levels of homocysteine are related to heart disease, stroke, cancer, osteoporosis and memory loss and depression in older adults. High homocysteine is treated with supplemental folic acid. Because of the link with birth defects, folic acid supplements are being recommended routinely to women of childbearing age. The richest sources of folate (the name for the family of folic acids found in food) are green vegetables, orange juice and beans. The RDA for folic acid is 400 mcg.