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 kidneydialysis.
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 coloncancer 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 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.
- 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.
- Reducing the risk of pancreatic cancer.
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.
- 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.
Side Effects & Safety
Folic acid is LIKELY SAFE for most people. Most adults do not experience any side effects when consuming the recommended amount each day, which is 400 mcg.
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.
Don't take more than 400 mcg per day unless directed by your healthcare provider.
Moderate Interaction Be cautious with this combination
- Fosphenytoin (Cerebyx) interacts with FOLIC ACID
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) interacts with FOLIC ACID
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) interacts with FOLIC ACID
Phenobarbital (Luminal) is used for seizures. Taking folic acid can decrease how well phenobarbital (Luminal) works for preventing seizures.
- Phenytoin (Dilantin) interacts with FOLIC ACID
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) interacts with FOLIC ACID
Primidone (Mysoline) is used for seizures. Folic acid might cause seizure in some people. Taking folic acid can along with primidone (Mysoline) might decrease how well primidone works for preventing seizures.
- Pyrimethamine (Daraprim) interacts with FOLIC ACID
Pyrimethamine (Daraprim) is used to treat parasite infections. Folic acid might decrease the effectiveness of pyrimethamine (Daraprim) for treating parasite infections.
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.