Final answer:
The exact percentage of the decrease in Neural Tube Defects since the mandatory fortification of folic acid in 1998 is not specified, but there has been a significant decrease. Folic acid is vital for fetal brain and spinal cord development, with a recommended intake of at least 400 µg/day for women who might become pregnant.
Step-by-step explanation:
Regarding the decrease in Neural Tube Defects (NTDs) since the mandatory fortification of folic acid in 1998, the correct percentage of decrease is not provided in the context of the question. However, it is widely recognized that there has been a significant decrease in the incidence of NTDs since the fortification process began.
Folic acid is crucial for proper fetal development, particularly for the brain and spinal cord. The Food and Nutrition Board of the Institute of Medicine recommends that all women who might become pregnant consume at least 400 µg/day of folate from supplements or fortified foods.
This recommendation is due to the critical role that folate plays in DNA synthesis and repair, and thus, in the prevention of NTDs during the earliest stages of embryonic development, often before a woman knows she is pregnant.