What is it?
Folate and folic acid are forms of a water-soluble B vitamin. Folate occurs naturally in food, and folic acid is the synthetic form of this vitamin. 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 (such as spinach, broccoli, and lettuce), okra, asparagus, fruits (such as bananas, melons, and lemons) beans, yeast, mushrooms, meat (such as beef liver and kidney), orange juice, and tomato juice.
Folic acid is used for preventing and treating low blood levels of folate (folate deficiency), as well as its complications, including “tired blood” (anemia) and the inability of the bowel to absorb nutrients properly. Folic acid is also used for other conditions commonly associated with folate deficiency, including ulcerative colitis, liver disease, alcoholism, and kidney dialysis.
Women who are pregnant or might become pregnant take folic acid to prevent miscarriage and “neural tube defects,” birth defects such as spina bifida that occur when the fetus’s spine and back do not close during development.
Some people use folic acid to prevent colon cancer or cervical cancer. It is also used to prevent heart disease and stroke, as well as to reduce blood levels of a chemical called homocysteine. High homocysteine levels might be a risk for heart disease.
Folic acid is used for memory loss, Alzheimer’s disease, age-related hearing loss, preventing the eye disease age-related macular degeneration (AMD), reducing signs of aging, weak bones (osteoporosis), jumpy legs (restless leg syndrome), sleep problems, depression, nerve pain, muscle pain, AIDS, a skin disease called vitiligo, and an inherited disease called Fragile-X syndrome. It is also used for reducing harmful side effects of treatment with the medications lometrexol and methotrexate.
Some people apply folic acid directly to the gum for treating gum infections.
Folic acid is often used in combination with other B vitamins.
How effective is it?
Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
The effectiveness ratings for FOLIC ACID are as follows:
- Folate deficiency. Taking folic acid improves folate deficiency.
Likely effective for…
- Kidney disease. About 85% of people with serious kidney disease have high levels of homocysteine. High levels of homocysteine have been linked to heart disease and stroke. Taking folic acid lowers homocysteine levels in people with serious kidney disease. However, folic acid supplementation does not appear to reduce the risk of heart disease-related events.
- High amounts of homocysteine in the blood (hyperhomocysteinemia). High levels of homocysteine have been linked to heart disease and stroke. Taking folic acid lowers homocysteine levels by 20% to 30% in people with normal to slightly elevated homocysteine levels. It is recommended that people with homocysteine levels greater than 11 micromoles/L supplement with folic acid and vitamin B12.
- Reducing harmful effects of a medicine called methotrexate. Taking folic acid seems to reduce nausea and vomiting, which are possible side effects of methotrexate treatment.
- Birth defects (neural tube defects). Consuming high amounts of folate in the diet and taking folic acid supplements during pregnancy reduces the risk of neural tube birth defects.
Possibly effective for…
- Age-related vision loss (age-related macular degeneration). Some research shows that taking folic acid with other vitamins including vitamin B6 and vitamin B12 reduces the risk of developing age-related vision loss.
- Depression. Limited research suggests that taking folic acid along with antidepressants seems to improve symptoms in people with depression.
- High blood pressure. Research suggests that taking folic acid daily for at least 6 weeks reduces blood pressure in people with high blood pressure. However, taking folic acid with blood pressure medication does not seem to lower blood pressure any more than taking just the medication alone.
- Gum problems due to a drug called phenytoin. Applying folic acid to the gums seems to prevent gum problems caused by phenytoin. However, taking folic acid by mouth does not seem to improve symptoms of this condition.
- Gum disease during pregnancy. Applying folic acid to the gums seems to improve gum disease during pregnancy.
- A skin discoloration disorder called vitiligo. Taking folic acid by mouth seems to improve symptoms of vitiligo.
Possibly ineffective for…
- Cancer of the white blood cells (acute lymphoblastic leukemia). Taking folate during pregnancy does not reduce the risk of childhood cancer of the white blood cells.
- Breast cancer. Consuming folate in the diet might lower the risk of developing breast cancer in women who also eat high amounts of methionine, vitamin B12 (cyanocobalamin), or vitamin B6 (pyridoxine), but research is not consistent. Other research suggests that taking folic acid supplements alone does not lower the risk of breast cancer.
- Heart disease. Research suggests that taking folic acid alone or with vitamin B6 (pyridoxine) and vitamin B12 does not reduce the risk of death or heart disease-related events in people with heart disease.
- Chronic fatigue syndrome. Daily injections of folic acid appear to have no effect on symptoms of chronic fatigue syndrome.
- Toxicity from the drug lometrexol. Daily injections of folic acid appear to have no effect on symptoms of chronic fatigue syndrome.
- Prostate cancer.Folic acid levels in the blood do not seem to be linked with the risk of developing prostate cancer.
- Stroke. Research suggests that people with high folate intake from the diet have a lower risk of stroke due to blood vessel ruptures (hemorrhagic stroke). However, folic acid does not seem to reduce the risk of stroke due to blood clots (ischemic stroke).
Likely ineffective for…
- Inherited disease called Fragile-X syndrome.Taking folic acid by mouth does not improve symptoms of fragile-X-syndrome.
Insufficient evidence to rate effectiveness for…
- Alzheimer’s disease. Limited evidence suggests that elderly people who consume more folic acid than the recommended dietary allowance (RDA) appear to have a lower risk of developing Alzheimer’s disease than people who consume less folic acid.
- Preventing re-blockage of blood vessels after angioplasty. There is inconsistent evidence on the benefits of taking folic acid after a procedure to widen the blood vessels. Taking folic acid plus vitamin B6 and vitamin B12 might actually interfere with healing in cases where a device (stent) is inserted in the blood vessel to keep it open.
- Bipolar disorder. Taking folic acid does not appear to improve the antidepressant effects of lithium in people with bipolar disorder. However, taking folate with the medication valproate improves the effects of valproate.
- Cervical cancer. There is some evidence that increasing folic acid intake from dietary and supplement sources, along with thiamine, riboflavin, and vitamin B12, might help to prevent cervical cancer.
- Memory and thinking skills in older people. There is conflicting evidence about the role of folic acid in age-related decline in memory and thinking skills. Some research shows that taking folic acid might improve mental function in older people. However, other research suggests no benefit.
- Colorectal cancer. Some research suggests that taking folic acid by mouth as a supplement or in the diet lowers the risk for developing colorectal cancer. However, contradictory evidence exists.
- Diabetes. Taking folic acid supplements does not seem to benefit people with diabetes.
- Epilepsy. Taking folic acid does not reduce seizures in people with epilepsy.
- Esophageal cancer. Research suggests that consuming more folate in the diet lowers the risk for developing esophageal cancer.
- High amounts of homocysteine in the blood caused by the drug fenofibrate. Taking folic acid every other day might lower levels of homocysteine in the blood caused by the drug fenofibrate.
- Stomach cancer. Research suggests that taking folic acid reduces the risk of developing some types of stomach cancer.
- Gout. Early research suggests that folate might reduce the risk of gout.
- Hearing loss. Low levels of folate in the blood seem to be related to the risk for sudden hearing loss in adults. Some evidence suggests that taking folic acid daily for 3 years slows the decline of hearing loss in older people who have low folate levels. It is not clear if folic acid supplementation reduces hearing loss in people with normal folate levels.
- Male infertility. Some research suggests that taking folic acid plus zinc sulfate daily can increase sperm count in men with low sperm counts.
- Lung cancer. There does not appear to be a relationship between low levels of folic acid and lung cancer in most people.
- Helping medicines used for chest pain work longer. Some evidence suggests that taking folic acid does not help medications for chest pain (nitrates) work longer.
- Cleft lip. Some research suggests that taking folic acid during pregnancy lowers the risk of left lip. However, other research shows no effect.
- Pancreatic cancer. Eating more than 280 mcg of folate in the diet daily is linked to a lower risk of developing pancreatic cancer. However, other research suggests that folate intake is not linked to pancreatic cancer risk.
- Restless leg syndrome. Taking folic acid seems to reduce symptoms of restless leg syndrome. Researchers are studying whether folic acid deficiency causes restless leg syndrome.
- Sickle-cell disease. Taking folic acid might lower homocysteine levels. However, it is not known if this will benefit people with sickle-cell disease.
- Cancer due to a disease called ulcerative colitis. Early research suggests that taking folic acid might prevent cancer in people with ulcerative colitis.
- Liver disease.
- Weak bones (osteoporosis).
- Other conditions.
More evidence is needed to rate folic acid for these uses.
How does it work?
Folic acid is needed for the proper development of the human body. It is involved in producing the genetic material called DNA and in numerous other bodily functions.
Are there safety concerns?
Folic acid is LIKELY SAFE for most people when taken by mouth or injected into the body. Most adults do not experience any side effects when used in doses less than 1000 mcg daily.
Folic acid is POSSIBLY UNSAFE when taken by mouth in large doses, long-term. High doses of folic acid might cause abdominal cramps, diarrhea, rash, sleep disorders, irritability, confusion, nausea, stomach upset, behavior changes, skin reactions, seizures, gas, excitability, and other side effects.
There is some concern that taking too much folic acid for a long period of time might cause serious side effects. Some research suggests that taking folic acid in doses of 800-1200 mcg might increase the risk of heart attack in people who have heart problems. Other research suggests that taking these high doses might also increase the risk of cancer such as lung or prostate cancer.
Special precautions & warnings:
Pregnancy and breast-feeding: Folic acid is LIKELY SAFE when taken by mouth appropriately during pregnancy and breast-feeing. Taking 300-400 mcg of folic acid daily is commonly used during pregnancy to prevent birth defects.
Procedures to widen narrowed arteries (angioplasty): Using folic acid, vitamin B6, and vitamin B12 intravenously (by IV) or by mouth might worsen narrowed arteries. Folic acid should not be used by people recovering from this procedure.
Cancer: Early research suggests that taking 800-1000 mcg 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.
Heart disease: Early research suggests that taking folic acid plus vitamin B6 might increase the risk for heart attack in people with a history of heart disease.
Anemia caused by vitamin B12 deficiency: Taking folic acid might mask anemia caused by vitamin B12 deficiency and delay appropriate treatment.
Seizure disorder: Taking folic acid supplements might make seizures worse in people with seizure disorders, particularly in high doses.
Are there interactions with medications?
- 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)
- 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.
- Fosphenytoin (Cerebyx)
- Fosphenytoin (Cerebyx) is used for seizures. The body breaks down fosphenytoin (Cerebyx) to get rid of it. Folic acid can increase how quickly the body breaks down fosphenytoin (Cerebyx). Taking folic acid along with fosphenytoin (Cerebyx) might decrease the effectiveness of fosphenytoin (Cerebyx) for preventing seizures.
- Methotrexate (MTX, Rheumatrex)
- Methotrexate (MTX, Rheumatrex) works by decreasing the effects of folic acid in the body’s cells. Taking folic acid pills along with methotrexate might decrease the effectiveness of methotrexate (MTX, Rheumatrex).
- Phenobarbital (Luminal)
- Phenobarbital (Luminal) is used for seizures. Taking folic acid can decrease how well phenobarbital (Luminal) works for preventing seizures.
- Phenytoin (Dilantin)
- The body breaks down phenytoin (Dilantin) to get rid of it. Folic acid might increase how quickly the body breaks down phenytoin (Dilantin). Taking folic acid and taking phenytoin (Dilantin) might decrease the effectiveness of phenytoin (Dilantin) and increase the possibility of seizures.
- Primidone (Mysoline)
- Primidone (Mysoline) is used for seizures. Folic acid might cause seizures in some people. Taking folic acid along with primidone (Mysoline) might decrease how well primidone works for preventing seizures.
- Pyrimethamine (Daraprim)
- Pyrimethamine (Daraprim) is used to treat parasite infections. Folic acid might decrease the effectiveness of pyrimethamine (Daraprim) for treating parasite infections.
Are there interactions with herbs and supplements?
- Green tea
- There is some concern that green tea might keep folic acid from working the way it should in the body. This might lead to a condition that is similar to folic acid deficiency.
Are there interactions with foods?
- Taking folic acid with food reduces its absorption slightly, but probably not enough to be important.
- Researchers don’t agree on whether or not folic acid interferes with zinc absorption. But for people who get enough zinc in their diet, the effect of folic acid probably isn’t important.
What dose is used?
The following doses have been studied in scientific research:
- For folic acid deficiency: the typical dose is 250-1000 mcg (micrograms) per day.
- For preventing neural tube defects: at least 400 mcg of folic acid per day from supplements or fortified food should be taken by women capable of becoming pregnant and continued through the first month of pregnancy. Women with a history of previous pregnancy complicated by such neural tube defects usually take 4 mg per day beginning one month before and continuing for three months after conception.
- For reducing colon cancer risk: 400 mcg per day.
- For treating high levels of homocysteine in the blood:
- 0.5-5 mg (milligrams)/day has been used, although 0.8-1 mg/day is appears to be more effective.
- In people with end-stage renal disease, high homocysteine levels may be more difficult to treat, and doses of 0.8-15 mg/day have been used. Other dosage plans such as 2.5-5 mg 3 times weekly have also been used. Doses higher than 15 mg daily do not seem to be more effective.
- For improving the response to medications for depression: 200-500 mcg daily has been used.
- For vitiligo: 5 mg is typically taken twice daily.
- For reduction of toxicity associated with methotrexate therapy for rheumatoid arthritis (RA) or psoriasis: 1 mg/day is probably enough, but up to 5 mg/day may be used.
- For preventing macular degeneration: folic acid 2.5 mg, vitamin B12 (cyanocobalamin) 1000 mcg, and vitamin B6 (pyridoxine) 50 mg daily.
The adequate intakes (AI) for infants are 65 mcg for infants 0-6 months and 80 mcg for infants 7-12 months of age. The recommended dietary allowances (RDAs) for folate in DFE, including both food folate and folic acid from fortified foods and supplements are: Children 1-3 years, 150 mcg; Children 4-8 years, 200 mcg; Children 9-13 years, 300 mcg; Adults over 13 years, 400 mcg; Pregnant women 600 mcg; and breast-feeding women, 500 mcg. The tolerable upper intake levels (UL) of folate are 300 mcg for children 1-3 years of age, 400 mcg for children 4-8 years, 600 mcg for children 9-13 years, 800 mcg for adolescents 14-18 years, and 1000 mcg for everyone over 18 years of age.
5′-methyltetrahydrofolate, 5′-MTHF, Acide Folique, Acide Ptéroylglutamique, Acide Ptéroylmonoglutamique, Acido Folico, B Complex Vitamin, Complexe de Vitamines B, Complexe Vitaminique B, Dihydrofolate, Folacin, Folacine, Folate, Folinic Acid, L-methylfolate, Methylfolate, Méthylfolate, Pteroylglutamic Acid, Pteroylmonoglutamic Acid, Pteroylpolyglutamate, Tetrahydrofolate, Tétrahydrofolate, Vitamin B9, Vitamine B9.
To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.