Folic acid, a vitamin found naturally in green leafy vegetables and legumes, is essential for making the building blocks of DNA.  And since copying DNA is an important part of what cells do before they divide, it’s critical for cell division.  Developing fetuses have very rapidly dividing cells, so it’s not surprising that folic acid deficiency has been linked to birth defects, specifically brain and spinal cord abnormalities. To prevent these birth defects, physicians for many...