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Folic Acid

Other name(s):

vitamin B-9, folacin, folate, tetrahydrofolic acid, tetrahydropteroylglutamic acid, THF

General description

Folic acid, folate, or vitamin B-9, is a water-soluble vitamin. It plays an important part in cell division and in making cells in the blood-forming organs and bone marrow. It also plays a role in the development of the fetal spinal cord during pregnancy. Like the other B vitamins, folic acid plays an important role in energy production.

The body converts folic acid to tetrahydrofolic acid. Tetrahydrofolic acid plays an important part in cell division. It’s involved in nucleic acid (DNA and RNA) synthesis.

Folic acid deficiency causes larger-than-normal red blood cells and other abnormalities in white and red blood cells. This is called macrocytic anemia.

Research suggests that folic acid supplements can reduce the incidence of neural tube defects (spina bifida) in newborn infants by up to 50%. For this reason, the National Institutes of Health and Centers for Disease Control and Prevention recommend that women of childbearing age take a minimum of 400 micrograms (mcg) of folic acid per day. To be effective, these requirements must be met on a daily basis, starting at least three months before becoming pregnant.

According to the American Heart Association (AHA), folic acid supplements haven’t been shown to affect the development or recurrence of heart disease. At this time, the AHA doesn’t recommend the use of folic acid or vitamin B supplements to reduce the risk for heart disease.

Medically valid uses

Folic acid is used to prevent or treat folic acid deficiencies. Folic acid supplements can reduce the risk for neural tube defects in newborns by 50% if women take them before and during pregnancy.

Unsubstantiated claims

Please note that this section reports on claims that have not yet been substantiated through studies.

Folic acid may help treat uterine cervical dysplasia. It may also boost the immune system and help treat depression.

Recommended intake

Folic acid is measured in micrograms (mcg). The RDA is the Recommended Dietary Allowance.

Group

RDA

Children (1–3 years)

150 mcg

Children (4–8 years)

200 mcg

Children (9–13 years)

300 mcg

Children (14–18 years)

400 mcg

Adults (19 years and older)

400 mcg

Pregnant women

600 mcg

Breastfeeding women

500 mcg

 

Food source

Nutrient content per 100 grams

Brewer's yeast

1,888 mcg

Soybeans

661 mcg

Endive

444 mcg

Chickpeas

387.7 mcg

Lentils

321 mcg

Wheat germ

293 mcg

Beans

283 mcg

Liver, calf's (beef)

274 mcg

Split peas

217 mcg

Barley

198.8 mcg

Between 50–95% of folic acid may be destroyed in the cooking process. For instance, 100 g of raw lima beans contains 130 mcg of folic acid. But 100 g of canned lima beans (drained) contain sonly 13 mcg. This is just one-tenth of the raw, unprocessed product.

Folic acid is unstable in light. It’s easily oxidized in open air. You should store it in a light-resistant, airtight container. Keep it at room temperature.

Healthy people rarely have folic acid deficiency. But deficiencies can result from improper diet or a malabsorption syndrome. People with chronic hemolytic anemias, including sickle cell anemia, G6PD deficiency or thalassemia, may need folic acid supplements. Other conditions that increase the need for folic acid include:

  • Malabsorption syndromes. These can include lactose intolerance, celiac sprue, and cystic fibrosis.

  • Inflammatory bowel disease. These include Crohn's disease and ulcerative colitis.

  • Surgical removal of the jejunum (a part of the small intestine)

  • Cancer

  • Hemochromatosis

  • Underactive thyroid (hypothyroidism)

  • Dialysis

  • Moderate to heavy alcohol use

Women who are pregnant or breastfeeding may need to take supplements, but you should talk to your healthcare provider before doing so. The difference between prescription and over-the-counter prenatal vitamins is the amount of folic acid they contain.

The main disease linked with folic acid deficiency is megaloblastic anemia. In this condition, the red blood cells are enlarged (macrocytic). But they tend to have normal amounts of hemoglobin inside (normochromic).

If you have a folic acid deficiency, you have a reduced number of white blood cells. The nuclei of the white cells have excessive numbers of lobes (hypersegmentation).

Symptoms of folic acid deficiency include the following:

  • Swelling of your tongue

  • Diarrhea

  • Fatigue

  • Irritability

  • A slight decrease in mental function

Side effects, toxicity, and interactions

There are no known side effects linked with large doses of folic acid. But excessively large dosages may cause kidney damage. High doses may also cause a loss of appetite.

You shouldn’t take folic acid if you have untreated pernicious anemia unless your healthcare provider tells you to do so. High doses of folic acid can mask pernicious anemia. This is due to vitamin B-12 deficiency. Your healthcare provider may watch you closely if you have vitamin B-12 deficiency, and you also need folic acid supplements. 

Many medicines affect folic acid. This increases your need for supplemental doses of vitamin B-9. These include oral birth control pills. These medicines also include pentamidine, trimethoprim, triamterene, and pyrimethamine. You may also need folic acid supplements if you take medicines for seizures. These include phenytoin, primidone, and phenobarbital.

Some cancers are treated with folic acid antagonists. These are medicines that block the function of folic acid. You shouldn’t take folic acid supplements while you’re on chemotherapy unless your healthcare provider tells you to do so.

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