Folate was first isolated in an unknown form in 1941. The pharmaceutical form of folate is folic acid (pteroylglutamic acid). The major source of folate in the USA is food, with primary sources being grain products, especially fortified cereals, citrus fruits, and dried beans and lentils. However, the estimation of dietary intake of folate by food tables may not reflect actual intake because naturally occurring folate in the diet may be rendered inactive by cooking and food processing.