Folic acid or folate is a B vitamin. Normally 50-95% of folate in food is lost during home food preparation and food processing. The bioavailability of folate in a typical diet is about 50% of folic acid.
US Food and Nutrition Board recommends that women planning for pregnancy should consume extra 400mcg folic acid daily. This is to prevent Neural tube defects (NTD). NTD as brain defects normally occur 3 to 4 weeks after conception which is before you know that you are pregnant. Women planning for pregnancy should commence taking 400mcg folic acid 3 months prior to conception