Folic acid is the vitamin especially associated with fortified breakfast cereals and prevention of neural tube defects.
Folic acid is the synthetic form of folate, a B-group vitamin also known as vitamin B9. It is added to many foods, including some breakfast cereals, because adequate folate is essential for DNA synthesis and cell division. During early pregnancy, sufficient folic acid helps reduce the risk of neural tube defects.
The neural tube develops very early in embryonic life, often before a pregnancy is recognized. For that reason, public-health guidance commonly encourages people who may become pregnant to obtain recommended folic acid before conception and during early pregnancy.
Folate occurs naturally in foods such as leafy green vegetables, beans, peas, and citrus fruits. Fortification rules vary by country, so cereal labels and national dietary guidance remain important. Folic acid is not the same chemical form as naturally occurring food folate, though both supply vitamin B9 activity.