Folic acid

Definition

Folic acid is a water-soluble vitamin belonging to the B-complex group of vitamins . These vitamins help the body break down complex carbohydrates into simple sugars to be used for energy. Excess B vitamins are excreted from the body rather than stored for later use. This is why sufficient daily intake of folic acid is necessary.

Description

Folic acid is also known as folate or folacin. It is one of the nutrients most often found to be deficient in the Western diet. There is evidence that folate deficiency is a worldwide problem. Folic acid is found in leafy green vegetables, beans, peas and lentils, liver, beets, brussel sprouts, poultry, nutritional yeast, tuna, wheat germ, mushrooms, oranges, asparagus, broccoli, spinach, bananas, strawberries, and cantaloupes. In 1998, the U.S. Food and Drug Administration (FDA) required food manufacturers to add folic acid to enriched bread and grain products to boost intake. Pregnant women whose diets are deficient in folic acid have a greater chance of having a baby with neural tube defects (NTD), such as spina bifida .

General use

Folic acid works together with vitamin B ₁₂ and vitamin C to metabolize protein in the body. It is important for the formation of red and white blood cells. It is also necessary for the proper differentiation and growth of cells in fetal development. It is also used to form the nucleic acid of DNA and RNA. It increases the appetite and stimulates the production of stomach acid for digestion, and it aids in maintaining a healthy liver. A deficiency of folic acid may lead to anemia, in which there is decreased production of red blood cells. This situation reduces the amounts of oxygen and nutrients that are able to get to the tissues. Symptoms may include fatigue, reduced secretion of digestive acids, confusion, and forgetfulness. During pregnancy, a folic acid deficiency may lead to preeclampsia, premature birth, and increased bleeding after birth.

Pregnant women have an increased need for folic acid, both for themselves and their unborn child. Folic acid is necessary for the proper growth and development of the fetus. Adequate intake of folic acid is vital for the prevention of several types of birth defects, particularly NTDs. The neural tube of the embryo develops into the brain, spinal cord, spinal column, and the skull. If this tube forms incompletely during the first few months of pregnancy, a serious, and often fatal, defect results in spina bifida or anencephaly (formation of the head without the brain). Folic acid, taken from one year to one month before conception through the first four months of pregnancy, can reduce the risk of NTDs by 50 to 70 percent. It also helps prevent cleft lip and palate .

Research shows that folic acid can be used to successfully treat cervical dysplasia. This condition is considered to be a possible precursor to cervical cancer and is diagnosed as an abnormal Pap smear. Daily consumption of 1,000 mcg of folic acid for three or more months has resulted in improved cervical cells upon repeat Pap smears.

Precautions

Folic acid is not stable. It is easily destroyed by exposure to light, air, water, and cooking. Therefore, the supplement should be stored in a dark container in a cold, dry place, such as a refrigerator. Many medications interfere with the body's absorption and use of folic acid. This includes sulfa drugs, sleeping pills, estrogen, anticonvulsants, birth control pills, antacids, quinine, and some antibiotics . Using large amounts of folic acid (e.g., over 5,000 mcg per day) can mask a vitamin B ₁₂ deficiency and thereby risk of irreversible nerve damage.

Side effects

At levels of 5,000 mcg or less, folic acid is generally safe for use. Side effects are uncommon. However, large doses may cause nausea , decreased appetite, bloating, gas, decreased ability to concentrate, and insomnia. Large doses may also decrease the effects of phenytoin (Dilantin), a seizure medication.

Parental concerns

Pregnant women or those thinking of becoming pregnant should ensure that that they get the recommended amount of folic acid daily. As with all B-complex vitamins, it is best to take folic acid with the other B vitamins. Vitamin C is important to the absorption and functioning of folic acid in the body.

KEY TERMS

Homocysteine —A sulfur-containing amino acid.

Preeclampsia —A condition that develops after the twentieth week of pregnancy and results in high blood pressure, fluid retention that doesn't go away, and large amounts of protein in the urine. Without treatment, it can progress to a dangerous condition called eclampsia, in which a woman goes into convulsions.

Recommended Dietary Allowance (RDA) —The Recommended Dietary Allowances (RDAs) are quantities of nutrients in the diet that are required to maintain good health in people. RDAs are established by the Food and Nutrition Board of the National Academy of Sciences, and may be revised every few years. A separate RDA value exists for each nutrient. The RDA values refer to the amount of nutrient expected to maintain good health in people. The actual amounts of each nutrient required to maintain good health in specific individuals differ from person to person.

Water-soluble vitamins —Vitamins that are not stored in the body and are easily excreted. They must, therefore, be consumed regularly as foods or supplements to maintain health.

To correct a folic acid deficiency, supplements are taken in addition to food. Since the functioning of the B vitamins is interrelated, it is generally recommended that the appropriate dose of B-complex vitamins be taken in place of single B vitamin supplements. The Recommended Dietary Allowances (RDA) for folate is 400 mcg per day for adults, 600 mcg per day for pregnant women, and 500 mcg for nursing women. Medicinal dosages of up to 1,000–2,000 mcg per day may be prescribed. Nearly all multivitamin formulations for women include the RDA for folic acid.

Resources

BOOKS

Folic Acid: A Medical Dictionary, Bibliography, and Annotated Research Guide to Internet References. San Diego, CA: ICON Health Publications, 2004.

Heird, William C. "Nutritional Requirements." In Nelson Textbook of Pediatrics , 17th ed. Edited by Richard E. Behrman, et al. Philadelphia: Saunders, 2003, pp. 153–56.

Rock, Cheryl L. "Nutrition in the Prevention and Treatment of Disease." In Cecil Textbook of Medicine , 22nd ed. Edited by Lee Goldman, et al. Philadelphia: Saunders, 2003, pp. 1308–11.

Russell, Robert M. "Vitamin and Trace Mineral Deficiency and Excess." In Harrison's Principles of Internal Medicine , 15th ed. Edited by Eugene Braunwald et al. New York: McGraw Hill, 2001, pp. 461–69.

PERIODICALS

Allen, L. H. "Folate and vitamin B12 status in the Americas." Nutrition Reviews 62, no. 6, Pt. 2 (2004): 29–33.

Bailey, L. B. "Folate and vitamin B12 recommended intakes and status in the United States." Nutrition Reviews 62, no. 6, Pt. 2 (2004): S14–20.

Baro, L., et al. "The administration of a multivitamin/mineral fortified dairy product improves folate status and reduces plasma homocysteine concentration in women of reproductive age." International Journal of Vitamin and Nutritional Research 74, no. 3 (2004): 234–40.

Rockel, J. E., et al. "Folic acid fortified milk increases red blood cell folate concentration in women of childbearing age." Asia Pacific Journal of Clinical Nutrition 13, supplement (2004): S84–7.

ORGANIZATIONS

American Academy of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211–2672. Web site: http://www.aafp.org/.

American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 60007–1098. Web site: http://www.aap.org/default.htm.

American Association of Naturopathic Physicians. 8201 Greensboro Drive, Suite 300, McLean, VA 22102. Web site: http://naturopathic.org/ .

American Heart Association. National Center, 7272 Greenville Avenue, Dallas, Texas 75231. Web site: http://www.americanheart.org/Heart_and_Stroke_A_Z_Guide/heim.html.

American Medical Association. 515 N. State Street, Chicago, IL 60610. Web site: http://www.ama-assn.org/.

American Osteopathic Association. 142 East Ontario Street, Chicago, IL 60611. Web site: http://www.osteopathic.org/

WEB SITES

"Folate (Folacin, Folic Acid)." Ohio State University Extension Fact Sheet. Available online at http://ohioline.osu.edu/hyg-fact/5000/5553.html (accessed November 18, 2004).

"Folic Acid." Centers for Disease Control and Prevention (CDC). Available online at http://www.cdc.gov/node.do/id/0900f3ec80010af9 (accessed November 18, 2004).

"Folic Acid." March of Dimes. Available online at http://www.marchofdimes.com/pnhec/173_769.asp (accessed November 18, 2004).

L. Fleming Fallon Jr., MD, DrPH