Overview

Folate and folic acid are forms of vitamin B9 used for deficiency and to prevent pregnancy complications. Many foods contain folate or have folic acid added.

Since 1998, folic acid has been added to cold cereals, flour, breads, pasta, bakery items, cookies, and crackers, as required by federal law. Foods that are naturally high in folate include leafy vegetables, okra, asparagus, certain fruits, beans, yeast, mushrooms, animal liver and kidney, orange juice, and tomato juice. Folic acid is also available as a supplement, and is often used in combination with other B vitamins.

Folic acid is used for preventing and treating low blood levels of folate (folate deficiency) and high blood levels of homocysteine (hyperhomocysteinemia). Folic acid is also taken during pregnancy to prevent serious birth defects such as spina bifida. Folic acid is also used for many other conditions including depression, stroke, decline in memory and thinking skills, and many others.

Uses & Effectiveness

Effective for

  • Folate deficiency. Taking folic acid improves folate deficiency.

Likely Effective for

  • High levels of homocysteine in the blood (hyperhomocysteinemia). This condition has been linked to heart disease and stroke. Taking folic acid by mouth lowers homocysteine levels in people with normal or high homocysteine levels and in people with kidney failure.
  • Toxicity caused by the drug methotrexate. Taking folic acid by mouth seems to reduce nausea and vomiting from methotrexate treatment.
  • Birth defects of the brain and spine (neural tube birth defects). Consuming folic acid 600-800 mcg by mouth daily during pregnancy reduces the risk of these birth defects. Folic acid can come from the diet or supplements. Some people who are at high risk should get 4000-5000 mcg daily.

Possibly Effective for

  • Decline in memory and thinking skills in older people. Taking folic acid by mouth, with or without other supplements, may improve memory and thinking skills in older people who have a larger decline in thinking skills than expected at that age. But it doesn't seem to work in older people who are experiencing the usual decline in thinking skills for their age.
  • Depression. Taking folic acid by mouth along with antidepressants seems to improve symptoms in some people with depression.
  • High blood pressure. Taking folic acid by mouth daily for at least 6 weeks reduces blood pressure in some people with high blood pressure who are not taking other blood pressure medications.
  • Gum enlargement caused by the drug phenytoin. Applying folic acid to the gums seems to prevent this issue. But taking folic acid by mouth doesn't seem to help.
  • Stroke. In areas of the world that don't add folic acid to grain products, taking folic acid supplements can reduce the risk of stroke. But supplements don't seem to be helpful for people who live in countries that do add folic acid to grain products.
  • A skin disorder that causes white patches to develop on the skin (vitiligo). Taking folic acid by mouth seems to improve symptoms of this condition.

Possibly Ineffective for

  • Low levels of healthy red blood cells (anemia) due to iron deficiency. Adding folic acid to an iron supplement does not help to treat anemia any better than taking an iron supplement alone.
  • Decline in memory and thinking skills that occurs normally with age. Taking folic acid by mouth doesn't seem to prevent a decline in mental function that occurs normally in healthy aging adults.
  • Cataracts. Taking folic acid by mouth with vitamin B6 and vitamin B12 does not prevent cataracts. In fact, it might increase the number of cataracts that need to be removed.
  • Diarrhea. Taking folic acid by mouth doesn't seem to prevent diarrhea in children who are at risk of malnutrition. In fact, it may even increase the risk of having diarrhea that lasts more than a few days.
  • Fall prevention. Taking folic acid by mouth with vitamin B12 does not seem to prevent falls in older people who are also taking vitamin D.
  • Male infertility. Taking folic acid by mouth, alone or with other ingredients, does not seem to improve male fertility.
  • Death of an unborn or premature baby. Taking folic acid by mouth during pregnancy does not seem to reduce the risk of a baby dying just before or after birth. But it does help prevent other health issues in the baby.
  • Cancer of the white blood cells (leukemia). Taking folate by mouth during pregnancy does not reduce the risk of this type of cancer in children.
  • Weak and brittle bones (osteoporosis). In elderly individuals with osteoporosis, taking folic acid by mouth with vitamin B12 and/or vitamin B6 does not seem to prevent broken bones.
  • Physical performance in elderly adults. Taking folic acid by mouth with vitamin B12 doesn't seem to help older people walk better or have stronger hands.
  • High blood pressure during pregnancy. High-dose folic acid supplements do not seem to reduce blood pressure during pregnancy, or the risk of developing a condition called pre-eclampsia.
  • Infection of the airways. Taking folic acid by mouth doesn't seem to prevent infections in the lungs in children at risk of malnutrition.

Likely InEffective for

  • Non-cancerous growths in the large intestine and rectum (colorectal adenoma). Taking folic acid supplements does not prevent growths in the large intestine or rectum.
  • An inherited condition marked by learning disabilities (fragile-X syndrome). Taking folic acid by mouth does not improve symptoms of fragile X syndrome.
  • Preterm birth. Taking folic acid by mouth during pregnancy does not decrease the risk of having a premature baby. But it does help to prevent other health issues in the baby.

There is interest in using folic acid for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful for these uses.

Side Effects

When taken by mouth: It is likely safe for most people to take folic acid in doses of no more than 1 mg daily. Doses higher than 1 mg daily may be unsafe. These doses might cause stomach upset, nausea, diarrhea, irritability, confusion, behavior changes, skin reactions, seizures, and other side effects.

Another form of folic acid, L-5-methyltetrahydrofolate (L-5-MTHF), can also be found in supplements. This type of folic acid is possibly safe for most people in doses up to about 400 mcg daily.

There is some concern that taking too much folic acid for a long time might cause serious side effects. Some research suggests that taking folic acid in doses of 0.8-1.2 mg daily might increase the risk for cancer or increase the risk of heart attack in people who have heart problems.

Special Precautions and Warnings

When taken by mouth: It is likely safe for most people to take folic acid in doses of no more than 1 mg daily. Doses higher than 1 mg daily may be unsafe. These doses might cause stomach upset, nausea, diarrhea, irritability, confusion, behavior changes, skin reactions, seizures, and other side effects.

Another form of folic acid, L-5-methyltetrahydrofolate (L-5-MTHF), can also be found in supplements. This type of folic acid is possibly safe for most people in doses up to about 400 mcg daily.

There is some concern that taking too much folic acid for a long time might cause serious side effects. Some research suggests that taking folic acid in doses of 0.8-1.2 mg daily might increase the risk for cancer or increase the risk of heart attack in people who have heart problems.

Pregnancy and breast-feeding: Folic acid 300-400 mcg daily is recommended during pregnancy to prevent certain birth defects. The maximum recommended amount of folic acid during pregnancy or breastfeeding is 800 mcg daily for those under 18 years of age and 1000 mcg daily for those over 18 years of age. Do not use more unless directed by a healthcare professional.

Another form of folic acid, L-5-methyltetrahydrofolate (L-5-MTHF), can also be found in supplements. This type of folic acid is possibly safe to take at a dose of up to 400 mcg daily when pregnant or breastfeeding.

Children: It is likely safe for children to take folic acid by mouth in the recommended amounts for their age. But children should avoid taking folic acid in doses that are higher than the daily upper limits. These limits are 300 mcg for 1-3 years of age, 400 mcg for 4-8 years of age, 600 mcg for 9-13 years of age, and 800 mcg for 14-18 years of age.

Another form of folic acid, L-5-methyltetrahydrofolate (L-5-MTHF), can also be found in supplements. This type of folic acid is possibly safe in children.

Procedures to widen narrowed arteries (angioplasty): Using folic acid, vitamin B6, and vitamin B12 might worsen narrowed arteries. Folic acid should not be used by people recovering from this procedure.

Cancer: Early research suggests that taking 0.8-1 mg of folic acid daily might increase the risk of cancer. Until more is known, people with a history of cancer should avoid high doses of folic acid.

Seizure disorder: Taking folic acid supplements, especially in high doses, might make seizures worse in people with seizure disorders.

Vitamin B12 deficiency: Taking folic acid supplements might improve certain lab tests in people with low vitamin B12 levels. This may make it seem like vitamin B12 deficiency is improved when it isn't. If left untreated, this could cause permanent nerve damage.

Interactions

    Moderate Interaction

    Be cautious with this combination

  • Fosphenytoin (Cerebyx) interacts with Folic Acid

    Fosphenytoin is used for seizures. The body breaks down fosphenytoin to get rid of it. Folic acid can increase how quickly the body breaks down fosphenytoin. Taking folic acid along with fosphenytoin might decrease the effects of fosphenytoin for preventing seizures.

  • Phenobarbital (Luminal) interacts with Folic Acid

    Phenobarbital is used for seizures. Taking folic acid can decrease how well phenobarbital works for preventing seizures.

  • Phenytoin (Dilantin) interacts with Folic Acid

    The body breaks down phenytoin to get rid of it. Folic acid might increase how quickly the body breaks down phenytoin. Taking folic acid and taking phenytoin might decrease the effectiveness of phenytoin and increase the possibility of seizures.

  • Primidone (Mysoline) interacts with Folic Acid

    Primidone is used for seizures. Folic acid might cause seizures in some people. Taking folic acid along with primidone might decrease how well primidone works for preventing seizures.

  • Pyrimethamine (Daraprim) interacts with Folic Acid

    Pyrimethamine is used to treat parasite infections. Folic acid might decrease the effects of pyrimethamine for treating parasite infections.

  • 5-Fluorouracil interacts with Folic Acid

    There is some concern that taking large amounts of folic acid with 5-fluorouracil might increase some side effects of 5-fluorouracil, especially stomach problems. Talk with your healthcare provider before taking folic acid.

  • Capecitabine (Xeloda) interacts with Folic Acid

    There is some concern that taking large amounts of folic acid might increase the side effects of capecitabine, especially stomach problems like diarrhea and vomiting. Talk with your healthcare provider before taking folic acid.

Dosing

Folic acid is an important nutrient. The amount that should be consumed on a daily basis is called the recommended dietary allowance (RDA). The RDA for folic acid is provided as Dietary Folate Equivalents, or DFE. This is because the body absorbs the folic acid in supplements better than the folate found in food. 1 mcg DFE is the same as 1 mcg of folate found in food. But 1 mcg DFE is the same as 0.6 mcg of folic acid supplements.

The RDA in adults is 400 mcg DFE daily. In pregnancy, the RDA is 600 mcg DFE daily. When breastfeeding, the RDA is 500 mcg DFE daily. In children, the RDA depends on age. Speak with a healthcare provider to find out what dose might be best for a specific condition.
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