Fig. 2.

Recommended folate intake and recommended folic acid supplementation for prevention of NTD during the periconceptional period (NTD, neural tube defects; D-A-CH, Deutschland–Austria–Confoederatio Helvetica (reference values for nutrient intake by the German Nutrition Society, Austrian Nutrition Society, Swiss Society for Nutrition Research and Swiss Society for Nutrition); NNR, Nordic Nutrition Recommendations (by Denmark, Finland, Iceland, Norway and Sweden); IOM, Institute of Medicine, Dietary Reference Intakes; WHO, Vitamin and Mineral Requirements in Human Nutrition ^{( 42 )}). Definition of periconceptional period adapted from Steegers-Theunissen et al.^{( 44 )}