Folic acid is a type of B vitamin. It is water-soluble, which means it cannot be stored in the body. Water-soluble vitamins dissolve in water. Leftover amounts of the vitamin leave the body through the urine. That means you need a continuous supply of the vitamin in your diet.

Folic acid works along with vitamin B12 and vitamin C to help the body break down, use, and create new proteins. The vitamin helps form red blood cells and helps produce DNA, the building block of the human body, which carries genetic information.

Folic acid also helps tissues grow and cells work. Taking the right amount of folic acid before and during pregnancy helps prevent certain birth defects, including spina bifida.

See: Folic acid and birth defect prevention

Folic acid supplements may also be used to treat folic acid deficiency, certain menstrual problems, and leg ulcers.

Folate occurs naturally in the following foods:

• Beans and legumes
• Citrus fruits and juices
• Wheat bran and other whole grains
• Dark green leafy vegetables
• Poultry, pork, shellfish
• Liver

(Folic acid is the man-made form of folate found in supplements.)

Folic acid deficiency may cause poor growth, gray hair, swollen tongue (glossitis), mouth ulcers, peptic ulcer, and diarrhea. It may also lead to certain types of anemias.

Too much folic acid usually doesn't cause harm, because the vitamin is regularly removed from the body through urine.

The best way to get the daily requirement of essential vitamins is to eat a balanced diet that contains a variety of foods from the food guide pyramid. Most people in the United States have an adequate dietary intake of folic acid because it is plentiful in the food supply.

There is good evidence that folic acid can help reduce the risk of certain birth defects (spina bifida and anencephaly). Women who are pregnant or planning to become pregnant should take at least 400 micrograms (mcg) of folic acid every day. Pregnant women need even higher levels of folic acid. Ask your health care provider which amount is best for you.

The Food and Nutrition Board at the Institute of Medicine recommends the following dietary intake for folate:

Infants

• 0 - 6 months: 65 mcg/day
• 7 - 12 months: 80 mcg/day

Children

• 1 - 3 years: 150 mcg/day
• 4 - 8 years: 200 mcg/day
• 9 - 13 years: 300 mcg/day

Adolescents and Adults

• Males age 14 and older: 400 mcg/day
• Females age 14 - 50: 400 mcg/day plus 400 mcg/day from supplements or fortified foods
• Females age 50 and over: 400 mcg/day

Specific recommendations depend on age, gender, and other factors (such as pregnancy). Many foods are now fortified with folic acid to help prevent birth defects.

The best way to get the daily requirement of essential vitamins is to eat a balanced diet that contains a variety of foods from the food guide pyramid.

Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, PantothenicAcid, Biotin, and Choline. National Academy Press, Washington, DC, 1998.

Hamrick I, Counts SH. Vitamin and mineral supplements. Wellness and Prevention. December 2008:35(4);729-747.

Rakel D, ed. Integrative Medicine. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2007.

Mason, MB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 237.