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Vitamin B9 (Folic Acid)

Folic acid, also called folate or vitamin B9, is critical to many body processes, including the health of your nervous system, blood, and cells. It protects against heart disease, birth defects, osteoporosis, and certain cancers.


Folic acid protects the body against, and helps treat, many disorders, including the following.


bulletBirth defects. Low levels of folic acid have been linked with birth defects. Half of neural tube defects (such as spina bifida) are believed to be preventable if women of childbearing age supplement their diets with folic acid. Studies suggest that the amount of folic acid needed to prevent neural tube defects is more easily reached with supplements than from dietary sources alone.
bulletHeart attacks and stroke. Folic acid is essential to a process that clears a substance called homocysteine from the blood. High homocysteine levels have been linked with increased risk of heart disease and stroke.
bulletCancers. Low levels of folic acid may play a role in cancer development, particularly cancers of the cervix, lung, and colon.
bulletOsteoporosis. Lack of folic acid, and the resulting increase in homocysteine levels, weakens bones, making them more likely to fracture.
bulletDepression and other mental problems. Folic acid is important for brain function. It helps regulate mood, sleep, and appetite. Increasing levels of folic acid has reversed negative mental or psychological symptoms in some people, particularly older people. Folic acid has a mild antidepressant effect, and taking folic acid supplements has been shown to improve the effect of the drug Prozac.


Folic acid is also beneficial in the following ways: prevents anemia, which can decrease the function and number of red blood cells, helps treat headaches, may relieve rheumatoid arthritis, can help with infertility treatment, may help acne, and may be useful for people with AIDS.

Dietary Sources

Foods that contain a significant amount of folic acid include liver, lentils, rice germ, brewer's yeast, soy flour, black-eyed peas, navy beans, kidney beans, peanuts, spinach, turnip greens, lima beans, whole wheat, and asparagus.

Food processing (for example, boiling, heating) can destroy folic acid. Storing food at room temperature for long periods of time can also destroy its folic acid content. As of January 1998, commercial grain products are fortified with folic acid.

Other Forms

B9 supplements are available as both folic acid and folinic acid. While folate is more stable, folinic acid is the most efficient form for raising body stores of the nutrient.

How to Take It

Folic acid comes as tablets, or as an injection that you get from your health care provider. Tablets are available in doses from 40 mcg to 1,000 mcg. The recommended dietary allowance (RDA) for folic acid depends on your age and sex (see below). Unless you are pregnant, you will likely get enough folic acid from your diet. Check with your health care provider before you start taking supplements and before giving folic acid supplements to a child.

The RDA for folic acid is as follows.


bulletInfants under 6 months: 25 mcg
bullet6 to 12 months: 35 mcg
bulletChildren 1 to 3 years: 50 mcg
bulletChildren 4 to 6 years: 75 mcg
bulletChildren 7 to 10 years: 100 mcg
bulletMale and female 11 to 14: 150 mcg
bulletMales 15 years and older: 400 mcg
bulletFemales 15 years and older: 400 mcg
bulletPregnant females: 400 mcg
bulletLactating females: 280 mcg



Folic acid toxicity is rare. High doses (above 15 mg) can cause stomach problems, sleep problems, skin reactions, and seizures. Folic acid supplementation can mask vitamin B12 deficiency, which can cause permanent damage to your nervous system. Folic acid supplementation should always include vitamin B12.

Possible Interactions

Birth control medications, anticonvulsants (such as phenytoin), and cholesterol-lowering medications, particularly cholestyramine, may effect the levels of folic acid in the blood as well as the body's ability to use this vitamin.

Sulfasalazine, a medication used for ulcerative colitis and Crohn's disease, may affect the absorption of folic acid.

Methotrexate, a medication used for the treatment of cancer and resistant rheumatoid arthritis, increases the need for folic acid.

When taken for long periods of time, aspirin, ibuprofen, acetaminophen, and other anti-inflammatory medications can also increase the need for folic acid.

Supporting Research

Bendich A, Deckelbaum R, eds. Prevention Nutrition: The Comprehensive Guide for Health Professionals. Totowa, NJ: Humana Press; 1997.

Bronstrup A, Hages M, Prniz-Langenohl R, Pietrzik K. Effects of folic acid and combinations of folic acid and vitamin B12 on plasma homocysteine concentrations in healthy, young women. Am J Clin Nutr. 1998;68:11041110.

Cancers, Nutrition and Food. Washington, DC: World Cancer Research Fund/American Institute for Cancer Research; 1997.

Ebly EM, Schaefer JP, Campbell NR, Hogan DB. Folate status, vascular disease and cognition in elderly Canadians. Age Ageing. 1998;27:485491.

1999 Drug Facts and Comparisons. Facts and Comparisons; 1998.

Endresen GK, Husby G. Methotrexate and folates in rheumatoid arthritis [in Norwegian]. Tidsskr Nor Laegeforen. 1999;119(4):534-537.

Giles WH, Kittner SJ, Croft JB, Anda RF, Casper ML, Ford ES. Serum folate and risk for coronary heart disease: Results from a cohort of US adults. Ann Epidemiol. 1998;8:490496.

Imagawa M. Extra-intestinal complications of ulcerative colitis: hematologic complication [in Japanese]. Nippon Rinsho. 1999;57(11):2556-2561.

Lewis DP, Van Dyke DC, Stumbo PJ, Berg MJ. Drug and environmental factors associated with adverse pregnancy outcomes. Part II: Improvement with folic acid. Ann Pharmacother. 1998;32:947961.

Malinow MR, Duell PB, Hess DL, et al. Reduction of plasma homocyst(e)ine levels by breakfast cereal fortified with folic acid in patients with coronary heart disease. N Engl J Med. 1998;338:10091015.

Matsui MS, Rozovski SJ. Drug-nutrient interaction. Clin Ther. 1982;4(6):423-440.

Morgan SL, Baggott JE, Lee JY, Alarcon GS. Folic acid supplementation prevents deficient blood folate levels and hyperhomocysteinemia during long-term, low-dose methotrexate therapy for rheumatoid arthritis: implications for cardiovascular disease prevention. J Rheumatol. 1998;25:441446.

Moscow JA. Methotrexate transport and resistance. Leuk Lymphoma. 1998;30(3-4):215-224.

Murray MT. Encyclopedia of Nutritional Supplements. Rocklin, Calif: Prima Health; 1996.

Ortiz Z, Shea B, Suarez-Almazor ME, et al. The efficacy of folic acid and folinic acid in reducing methotrexate gastrointestinal toxicity in rheumatoid arthritis. A metaanalysis of randomized controlled trials. J Rheumatol. 1998;25:3643.

Reavley N. Vitamins, etc. Melbourne, Australia: Bookman Press; 1998.

Rimm EB, Willett WC, Hu FB, et al. Folate and vitamin B6 from diet and supplements in relation to risk of coronary heart disease among women. JAMA. 1998;279:359364.

Ringer D, ed. Physician's Guide to Nutriceuticals. St. Joseph, Mich: Nutritional Data Resources; 1998.

Seligmann H, Potasman I, Weller B, Schwartz M, Prokocimer M. Phenytoin-folic acid interaction: a lesson to be learned. Clin Neuropharmacol. 1999;22(5):268-272.

Watkins ML. Efficacy of folic acid prophylaxis for the prevention of neural tube defects. Ment Retard Dev Disab Res Rev. 1998;4:282290.

Wolf PA. Prevention of stroke. Lancet. 1998;352 (suppl III):1518.

Copyright 2000 Integrative Medicine Communications

The publisher does not accept any responsibility for the accuracy of the information or the consequences arising from the application, use, or misuse of any of the information contained herein, including any injury and/or damage to any person or property as a matter of product liability, negligence, or otherwise. No warranty, expressed or implied, is made in regard to the contents of this material. No claims or endorsements are made for any drugs or compounds currently marketed or in investigative use. This material is not intended as a guide to self-medication. The reader is advised to discuss the information provided here with a doctor, pharmacist, nurse, or other authorized healthcare practitioner and to check product information (including package inserts) regarding dosage, precautions, warnings, interactions, and contraindications before administering any drug, herb, or supplement discussed herein