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Evidence BasedFolic Acid: Everything You Need to Know

Medically reviewed by Jared Meacham, PhD., RD, CSCS — Written by Stephanie Watson — Updated on June 24, 2025

Vs. folate
Benefits & uses
Side effects & precautions
How to take

Folic acid is a synthetic form of vitamin B9 that’s often added to fortified foods and used in supplements. It has numerous benefits, and some risks.

Folic acid is a water-soluble vitamin. It’s a synthetic version of folate, one of the B vitamins.

Because your body can’t make folate, you need to get it from your diet.

Some foods naturally contain folate. Folic acid is added to other foods. You can also get folic acid from dietary supplements.

What’s the difference between folate and folic acid?

Although the terms “folate” and “folic acid” are often used interchangeably, they are actually different forms of the same vitamin: vitamin B9.

Folic acid has a different structure than folate and has slightly different effects in your body. “Folate” is the generic name that encompasses all forms of vitamin B9, including folic acid and 5-MTHF. Folic acid is a specific synthetic form of this vitamin.

You can find folate in plant and animal foods like these:

spinach
kale
broccoli
avocado
citrus fruits
eggs
beef liver

Folic acid is added to foods such as flour, ready-to-eat breakfast cereals, and breads.

It’s also in dietary supplements, such as multivitamins.

What does the body use folate for?

Your body uses folate to:

make and repair DNA
help cells grow, divide, and work properly
produce certain proteins
help red blood cells mature

Folate deficiency can lead to many health problems, including:

anemia
an increased risk of heart disease and certain cancers
developmental irregularities in infants if pregnant people don’t get enough folate

Many countries, including the United States, require certain grain products to be fortified with folic acid. Folic acid fortification helps prevent neural tube irregularities in infants.

Recommended intake levels

Read about the recommended intake levels for folate here.

Benefits and uses

Both folic acid and folate are used in supplements. Although these two nutrients treat the same conditions, they are metabolized differently in the body and can affect health in different ways.

Here are some common uses and benefits of folic acid supplements.

Treating folate deficiency

Folate deficiency can happen for many reasons. Some possible causes of folate deficiency are:

a lack of folate in your diet
diseases or surgeries that affect how your body absorbs folate, including celiac disease, short bowel syndrome, and gastric bypass surgery
no stomach acid (achlorhydria) or low stomach acid (hypochlorhydria)
drugs that affect folate absorption, including methotrexate and sulfasalazine (Azulfadine)
alcohol use disorder
pregnancy
hemolytic anemia
dialysis

Consuming too little folate can cause complications such as anemia, fetal development issues, mental impairment, impaired immune function, and depression. Taking folic acid or folate supplements can bring up your levels and prevent these complications.

Preventing birth defects and pregnancy complications

Folic acid supplements can help to prevent neural tube irregularities, including spina bifida and anencephaly. Getting enough folic acid during pregnancy can reduce the chance that your baby will be born with one of these conditions.

Folic acid supplements not only help prevent fetal development issues but also help lower the risk of pregnancy complications such as preeclampsia.

Maintaining brain health

Low blood folate levels are linked to poor mental function and an increased risk of dementia. Even folate levels that are technically normal but on the low side might increase the risk of mental impairment in older adults.

Adequate folate intake may also help protect against Alzheimer’s disease.

In a 2019 study in 180 adults with mild cognitive impairment, taking 400 mcg of folic acid supplements daily for 2 years improved measures of brain function and reduced blood levels of proteins that are involved in Alzheimer’s disease.

Another older 2016 study looked at 121 people with newly diagnosed Alzheimer’s disease who were being treated with the medication donepezil (Aricept).

Those who also took 1,250 mcg of folic acid per day for 6 months had improved thinking ability and less inflammation than those who took Aricept alone.

Treating mental health conditions

Folate is involved in the production of brain chemicals called neurotransmitters. Consuming too little folate has been linked to depression, schizophrenia, and other mental health conditions.

For example, people with depression may have lower blood levels of folate than people without depression.

A 2022 review of studies suggests that folic acid and folate supplements may help reduce symptoms of mental health conditions such as postpartum depression, schizophrenia, and bipolar disorder.

Taking folate supplements in addition to antidepressant medication may reduce depression symptoms more than taking antidepressant medication alone.

A review of seven studies found that treatment with folate supplements plus antipsychotic medication may improve symptoms in people with schizophrenia more than antipsychotic medication alone.

However, larger, more robust studies are needed to further support these findings.

Reducing heart disease risk factors

Folate-based supplements, including folic acid, may help improve heart health and reduce the risk of heart disease.

High levels of the amino acid homocysteine are thought to increase heart disease risk. Because folate helps break down homocysteine, low folate can lead to high homocysteine levels, also known as hyperhomocysteinemia.

Folic acid supplements can help bring down homocysteine levels and may lower heart disease risk.

Other possible benefits

Folic acid supplements may also help with these other health conditions:

Diabetes. Folate supplements may help improve blood sugar regulation and reduce insulin resistance in people with diabetes. Because the diabetes drug metformin can lower folate levels, you may need a supplement if your levels are low.
Fertility issues. Folate can improve egg quality and help eggs grow and implant in the uterus. Taking folate may increase the chance of getting pregnant and carrying a baby to term. People who use assisted reproductive technology to conceive may be more likely to have a baby if they have a higher intake of supplemental folate.
Inflammation. Inflammation plays a role in many diseases. Folic acid and folate supplements have been shown to reduce markers of inflammation such as C-reactive protein.
Kidney disease. The kidneys usually filter waste out of the blood, but when the kidneys are damaged, homocysteine can build up. About 85% of people with chronic kidney disease have too much homocysteine in their blood. Folic acid supplements may help reduce homocysteine levels and heart disease risk in people with kidney disease.

Larger studies are still needed to confirm the benefits of folate supplementation.

This list doesn’t include every possible benefit of folic acid. There are many other reasons people may use folate-based supplements.

Consult a healthcare professional

Before starting folic acid supplements, it’s important to talk with a healthcare professional. They can make sure the supplements will not interact negatively with other medications you may be taking.

Side effects and precautions

Eating folate-rich foods and taking natural forms of folate such as 5-MTHF are generally considered safe. But taking high doses of folic acid through supplements could potentially lead to a buildup of unmetabolized folic acid in your blood.

“Unmetabolized” means your body hasn’t broken down the folic acid or converted it into other forms of folate. No confirmed health risks due to unmetabolized folic acid have yet been found, but undiscovered risks may still exist.

It’s important to note that most children and adults in the United States get enough folate from food and don’t need to take a folic acid supplement.

How to take

Folate and folic acid can be found in many forms. They are added to multinutrient supplements, including multivitamins and B-complex vitamins. Most adult supplements contain 680–1,360 mcg DFE (400–800 mcg of folic acid).

The Tolerable Upper Intake Level (UL) is the highest daily folic acid dose you can take without experiencing harmful side effects.

The UL includes only folate from fortified foods and dietary supplements. High intake of naturally occurring folate from food has not been shown to cause any adverse effects.

The UL for folate in supplements and fortified foods is:

Age range	UL
adults	1,000 mcg
children ages 14–18	800 mcg
children ages 9–13	600 mcg
children ages 4–8	400 mcg
children ages 1–3	300 mcg

Most children in the United States get enough folate from food, and 30–66% of children ages 1–13 who take folic acid supplements exceed the UL for their age group. Ask a pediatrician before giving your child a folic acid supplement to make sure it’s safe.

You can take all forms of folic acid with or without food.

Before taking folic acid

A healthcare professional might recommend a folic acid supplement if you have a deficiency or you are pregnant or thinking about getting pregnant.

Let a healthcare professional know what other prescription and over-the-counter medications you take. Folic acid may interact with some medicines.

Storage and handling

Store folic acid supplements in a cool, dry place. Keep supplements away from humid areas, such as the bathroom.

Overdose

There’s no set upper limit for folate in foods. Because folate is water-soluble, your body removes any extra you consume. Still, it may be possible to develop side effects if you take folic acid supplements in amounts greater than the UL.

A healthcare professional may recommend higher doses if you have a folate deficiency. Avoid taking more than the UL unless a healthcare professional directs you to do so.

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If you’re considering getting pregnant, it’s recommended that you take a folic acid supplement and eat a diet high in folate. If you think you have a folate deficiency, a healthcare professional can diagnose it and help you get the folate you need.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Asbaghi O, et al. (2021). Effects of folic acid supplementation on inflammatory markers: A grade-assessed systematic review and dose–response meta-analysis of randomized controlled trials.https://pmc.ncbi.nlm.nih.gov/articles/PMC8308638/
Chen H, et al. (2016). Folic acid supplementation mitigates Alzheimer's disease by reducing inflammation: A randomized controlled trial.https://pmc.ncbi.nlm.nih.gov/articles/PMC4909909/
Cianciolo G, et al. (2017). Folic acid and homocysteine in chronic kidney disease and cardiovascular disease progression: Which comes first?https://pmc.ncbi.nlm.nih.gov/articles/PMC5662962/
Gaskins AJ, et al. (2019). Diet and fertility: A review.https://pmc.ncbi.nlm.nih.gov/articles/PMC5826784/
Folate. (2022).https://ods.od.nih.gov/factsheets/Folate-Consumer/
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Kaldygulova L, et al. (2023). Biological role of folic acid in pregnancy and possible therapeutic application for the prevention of preeclampsia.https://pmc.ncbi.nlm.nih.gov/articles/PMC9953465/
Khan KM, et al. (2023). Folic acid deficiency.https://www.ncbi.nlm.nih.gov/books/NBK535377/
Lam NSK, et al. (2022). The potential use of folate and its derivatives in treating psychiatric disorders: A systematic review.https://www.sciencedirect.com/science/article/pii/S0753332221013287
Li Y, et al. (2016). Folic acid supplementation and the risk of cardiovascular diseases: A meta‐analysis of randomized controlled trials.https://www.ahajournals.org/doi/full/10.1161/JAHA.116.003768
Ma F, et al. (2019). Effects of folic acid supplementation on cognitive function and Aβ-related biomarkers in mild cognitive impairment: A randomized controlled trial.https://pubmed.ncbi.nlm.nih.gov/29255930/
Maruvada P, et al. (2020). Knowledge gaps in understanding the metabolic and clinical effects of excess folates/folic acid: A summary, and perspectives, from an NIH workshop.https://www.sciencedirect.com/science/article/pii/S0002916522009091
Merrell BJ, et al. (2023). Folic acid.https://www.ncbi.nlm.nih.gov/books/NBK554487/
Owen MD, et al. (2021). Interaction between metformin, folate and vitamin B12 and the potential impact on fetal growth and long-term metabolic health in diabetic pregnancies.https://pmc.ncbi.nlm.nih.gov/articles/PMC8198407/
Roberts E, et al. (2018). Caveat emptor: Folate in unipolar depressive illness, a systematic review and meta-analysis.https://journals.sagepub.com/doi/abs/10.1177/0269881118756060?rfr_dat=cr_pub++0pubmed&url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org
Sakuma K, et al. (2018). Folic acid/methylfolate for the treatment of psychopathology in schizophrenia: A systematic review and meta-analysis.https://pubmed.ncbi.nlm.nih.gov/29785555/

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Evidence Based

This article is based on scientific evidence, written by experts and fact checked by experts.

Our team of licensed nutritionists and dietitians strive to be objective, unbiased, honest and to present both sides of the argument.

This article contains scientific references. The numbers in the parentheses (1, 2, 3) are clickable links to peer-reviewed scientific papers.

Medically reviewed by Jared Meacham, PhD., RD, CSCS — Written by Stephanie Watson — Updated on June 24, 2025

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Nutrition

Nutrition

What’s the difference between folate and folic acid?

What does the body use folate for?

Recommended intake levels

Benefits and uses

Treating folate deficiency

Preventing birth defects and pregnancy complications

Maintaining brain health

Treating mental health conditions

Reducing heart disease risk factors

Other possible benefits

Consult a healthcare professional

Side effects and precautions

How to take

Before taking folic acid

Storage and handling

Overdose

Just one thing

How we reviewed this article:

Evidence Based

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