Folic acid is the synthetic form of folate, which is a naturally occurring B vitamin. Folate helps make DNA and other genetic material. It is especially important in prenatal health.

Folate, also called vitamin B-9, is a B vitamin that naturally occurs in certain foods. Folic acid is the form of folate that manufacturers add to vitamin supplements and fortified foods.

This article explores the functions of folic acid in the body, its benefits, some sources, the recommended intakes, the risks, and the effects of deficiency.

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Folic acid may reduce the risk of preterm birth.

Folate is important for a range of functions in the body.

It helps the body make healthy new red blood cells, for example. Red blood cells carry oxygen throughout the body. If the body does not make enough of these, a person can develop anemia, leading to fatigue, weakness, and a pale complexion.

Without enough folate, a person can also develop a type of anemia called folate deficiency anemia.

Folate is also important for the synthesis and repair of DNA and other genetic material, and it is necessary for cells to divide.

Getting enough folate during pregnancy is particularly important. This is because folic acid is crucial for early fetal development, particularly with regard to the spinal cord.

Because of its importance for health, the Food and Drug Administration (FDA) requires manufacturers to add folic acid to enriched bread, pasta, rice, cereals, and other grain products in the United States.

Learn more about folate.

Folate deficiency occurs when there is not enough folate present in the body. This can lead to a type of anemia called megaloblastic anemia.

During pregnancy, folate deficiency increases the risk of congenital irregularities.

Some symptoms of folate deficiency include:

  • weakness
  • fatigue
  • trouble concentrating
  • headache
  • irritability
  • heart palpitations
  • sores on the tongue and inside the mouth
  • a change in color of the skin, hair, or fingernails
  • irritability, headache, heart palpitations, and shortness of breath

Some groups at increased risk of folate deficiency include:

  • people with alcohol use disorder
  • pregnant people
  • people of childbearing age
  • people with conditions that affect nutrient absorption, including irritable bowel disorder (IBD) and celiac disease
  • people with MTHFR polymorphism, which is a genetic condition that impairs the ability to convert folate to its active form and leads to elevated levels of an amino acid called homocysteine in the blood.

The body absorbs folic acid from supplements and fortified foods better than folate from naturally occurring foods.

The Office of Dietary Supplements recommend that people get the following dietary folate equivalents (DFEs) from food or vitamin sources:

AgeRecommended amount
0–6 months65 mcg dietary folate equivalent (DFE)
7–12 months80 mcg DFE
1–3 years150 mcg DFE
4–8 years200 mcg DFE
9–13 years300 mcg DFE
14–18 years400 mcg DFE
19+ years400 mcg DFE
During pregnancy400–800 mcg DFE
During lactation500 mcg DFE

It is important to note that folic acid can interact with certain medications and may not be safe for everyone to take. A person should speak to their doctor before increasing their folic acid or folate intake.

Most people get enough folate from their diet, and folate deficiency is rare in the United States. However, some people in particular can still benefit from taking folic acid supplements.

Pregnant people

The spinal cord is one of the first parts of the body to form in an embryo, and folate deficiency can lead to spinal cord irregularities.

It can also lead to neural tube irregularities, such as spina bifida and anencephaly. The neural tube is what forms the embryo’s early brain and spine.

Folic acid may also reduce the risks of preterm birth, heart irregularities, and cleft palate, among other things.

The Office on Women’s Health recommends that people who are or might become pregnant take 400–800 micrograms (mcg) of folic acid or L-5-Methyltetrahydrofolate, which is the natural form of dietary folate, per day. People with spina bifida or a family history of neural tube irregularities should take 4,000 mcg per day. Those who are breastfeeding or chestfeeding should aim to take around 500 mcg per day.

Since the FDA required adding folic acid to food in 1998, the number of babies born with neural tube irregularities has decreased.

Learn more about folic acid for pregnancy.

People with mood disorders

People with lower levels of folate may be more likely to experience depression. Research indicates that as many as 30% of severely depressed patients have a folate deficiency.

According to a 2021 study, having less than 6.0 nanograms per milliliter (ng/mL) of serum folate was associated with increased suicidal behavior in patients with depressive disorders.

However, whether taking folic acid supplements could improve depression symptoms is unclear. Studies from 2019 and 2018 seem to indicate that it may not. More research is necessary to determine the impact of folate on mood disorders. A person living with depression should discuss folate supplementation with their doctor.

Autism spectrum disorder

Some research suggests that taking folic acid before and during early pregnancy could reduce the baby’s chance of developing autism spectrum disorder (ASD). However, the research on this subject is contradictory.

For example, in a 2022 study, researchers found that taking in at least 400 micrograms (mcg) of folic acid from both food and supplements while pregnant was associated with a reduced chance of the offspring developing ASD.

On the other hand, another 2020 study found that high levels of folate during pregnancy may actually be associated with the development of ASD in the offspring.

More research will be necessary to determine the potential role of folic acid in this area.

People with rheumatoid arthritis

Doctors may use folic acid to support a methotrexate prescription for rheumatoid arthritis.

Methotrexate is an effective medication for this condition, but it may remove folate from the body, causing gastrointestinal symptoms.

Studies suggest that taking folic acid or L-5-Methyltetrahydrofolate supplements could reduce these side effects by around 79%.

Folic acid is present in dietary supplements and fortified foods, including bread, flour, cereals, and grains. It is also a common addition to B-complex vitamins.

Many foods are naturally high in folate. The best sources include:

  • beef liver
  • boiled spinach
  • black-eyed peas
  • asparagus
  • Brussels sprouts
  • lettuce
  • avocado
  • broccoli
  • mustard greens
  • green peas
  • kidney beans
  • canned tomato juice
  • Dungeness crab
  • orange juice
  • dry-roasted peanuts
  • fresh orange and grapefruit
  • papaya
  • banana
  • hard-boiled egg
  • cantaloupe

The following are answers to additional questions about folate and folic acid:

What are the side effects of folic acid?

There has been a consensus among many medical professionals that no serious side effects are associated with taking too much folic acid. Folic acid is water soluble, so the belief is that any excess will naturally pass through the urine. In very rare cases, people may report an upset stomach.

However, there are some studies that may contradict this belief. While the various results are conflicting, there is some evidence that too much unmetabolized folic acid in the blood may be associated with certain types of cancer and conditions such as anemia or insulin resistance in some cases.

Who should not take folic acid?

A person should speak to a doctor before taking folic acid if they have any of the following:

  • epilepsy
  • type 2 diabetes
  • rheumatoid arthritis
  • lupus
  • inflammatory bowel disease (IBD)
  • celiac disease

Certain medications used to treat these conditions can interact with folate. People undergoing kidney dialysis may also consider avoiding taking folic acid.

Are there alternatives to folic acid supplements?

There is some evidence that taking supplements containing L-5-Methyltetrahydrofolate, the active form of folate or folic acid, can have some benefits. It may work better for people taking drugs that interact with regular folate or people with MTHFR polymorphism, for example. However, a person should always ask their doctor before taking any supplement.

Folic acid is the synthetic form of folate, an important B vitamin. Most people get enough folate from their diet, but people at risk of deficiency and people who are pregnant or may become pregnant may need to take folic acid supplements.

Folic acid may also have additional health benefits, but there may also be risks. Certain people should avoid folic acid. A person should speak to their doctor before changing their diet to get more folate naturally or before starting any folic acid supplements.