The slices of bread you use to make a PB&J or tuna fish sandwich are fortified with an essential nutrient: folic acid (aka vitamin B9), which is also commonly found in leafy greens. The United States started fortifying bread with folic acid in 1998.
Folic acid is especially important for pregnant women. Those who don’t get enough may give birth prematurely or give birth to babies with neural tube defects in the brain, spine or spinal cord, including spina bifida and anencephaly. On average, around 2,500 pregnancies result in neural tube defects each year.
Today, because of folic acid supplementation, more than 50 percent of potential neural tube defects are prevented in newborns. In 2016, the U.S. Food and Drug Administration approved adding folic acid to corn masa flour, a staple in Latin American communities, to reduce the risk of neural tube defects in Hispanic babies.