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:

• Birth 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.
• Heart 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.
• Cancers. Low levels of folic acid may play a role in cancer development, particularly cancers of the cervix, lung, and colon.
• Osteoporosis. Lack of folic acid, and the resulting increase in homocysteine levels, weakens bones, making them more likely to fracture.
• Depression 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 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 symptoms of ulcerative colitis and rheumatoid arthritis, can help with infertility treatment, may help acne, and may be useful for people with AIDS.

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.

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.

Folic acid comes as tablets or as an injection that you get from your healthcare provider. Tablets are available in doses from 40 mcg to 1,000 mcg. Unless you are pregnant, you will likely get enough folic acid from your diet; although, under certain circumstances, a healthcare professional may recommend a therapeutic dose as high as 2,000 mcg/day for an adult.

Check with your healthcare provider before you start taking supplements and before giving folic acid supplements to a child.

Daily recommendations for dietary folate are listed below:

Pediatric

• Infants under 6 months: 65 mcg (adequate intake)
• Infants 7 to 12 months: 80 mcg (adequate intake)
• Children 1 to 3 years: 150 mcg (RDA)
• Children 4 to 8 years: 200 mcg (RDA)
• Children 9 to 13 years: 300 mcg (RDA)
• Adolescents 14 to 18 years: 400 mcg (RDA)

Adult

• 19 years and older: 400 mcg (RDA)
• Pregnant females: 600 mcg (RDA)
• Breastfeeding females: 500 mcg (RDA)

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.

Birth control medications, anticonvulsants (such as phenytoin), and cholesterol-lowering medications, particularly cholestyramine, may reduce the levels of folic acid in the blood as well as the body's ability to use this vitamin. Please refer to the consumer depletions monographs for these medications for additional information.

Sulfasalazine, a medication used for ulcerative colitis and Crohn's disease, may reduce the absorption of folic acid, leading to lower levels in the blood.

Methotrexate, a medication used to treat cancer and resistant rheumatoid arthritis, increases the body's need for folic acid. Folic acid reduces the side effects of methotrexate without decreasing its effectiveness. Consult your healthcare provider to determine whether taking folic acid may be appropriate for you if you are undergoing treatment with methotrexate.

Folic acid should not be taken at the same time as tetracycline, an antibiotic, because it interferes with the absorption and effectiveness of this medication. Folic acid alone or as part of a vitamin B complex supplement should be taken at different times from tetracycline.

When taken for long periods of time, aspirin, ibuprofen, acetaminophen, and other anti-inflammatory medications can also increase the body's need for folic acid. Please refer to the depletions monographs for these medications for more information.

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