In 1998 the Food and Nutrition Board of the National Academy of Sciences Institute of Medicine (IOM) recommended that women capable of becoming pregnant should take 400 micrograms of synthetic folic acid daily to reduce their risk for an NTD-affected pregnancy. Recommended sources are fortified foods, supplements or a combination of the two. In addition, the IOM advises women to consume food folate from a varied diet.

Source: Institute of Medicine. Dietary reference intakes for thiamin, riboflavin, niacin, vitamin B6, folate, vitamin B12, pantothenic acid, biotin, and choline, 2000.