Folic acid helps form the building blocks of DNA and RNA needed for protein synthesis in human cells. Rapidly growing tissues - such as those of a fetus - and rapidly regenerating cells - like red blood cells and immune cells - have an especially high need for folic acid.

Folic acid requirements increase during pregnancy. Deficiencies of folic acid during pregnancy are associated with low birth weight and an increased incidence of neural tube defects, including anencephaly and spina bifida. In one study, women at high risk of giving birth to babies with neural tube defects lowered their risk by as much as 72% by taking folic acid supplements prior to and during pregnancy. Medical experts, other healthcare professionals, and the March of Dimes recommend that all women of childbearing age supplement with 400 mcg of folic acid per day. Such supplementation would protect against the formation of neural tube defects during the time between conception and when pregnancy is discovered. If a woman waits until after pregnancy to begin taking folic acid supplements, it is likely too late to prevent a neural tube defect.

Folic acid deficiency has also been associated with high homocysteine levels and an increased risk for stroke, heart disease, and cognitive diseases like Alzheimer's disease. A folic acid deficiency may also result in a form of anemia (which can be remedied with supplementation).

It is difficult to accurately estimate how much folic acid is present in food. The best food sources appear to be vegetables (asparagus, broccoli, brussels sprouts, legumes), nuts, and seeds.

Additional Resources:

• Dietary Supplement Fact Sheet: Folate (from the National Institute of Health)
• Folic acid (folate) - U.S. National Library of Medicine
• Folic acid - Centers for Disease Control and Prevention (CDC)
• Folic acid - American Pregnancy Association
• Folic acid - American Cancer Society
• Folic acid - Wikipedia
• Folic acid - Linus Pauling Institute