5 Advantages of Folic Acid, Plus the Dosage and Dangers to Know

If you take a vitamin B complex every day, you’re likely well aware of the many benefits B vitamins have on your overall health. One of these essential vitamins is folate (or B9), which helps your body build DNA, RNA, and red blood cells—making it crucial during pregnancy for your baby’s development.

While most people get enough folate from foods like dark, leafy greens, beans, and nuts, it’s also added to certain food products and made into a supplement called folic acid—a form of folate that’s more easily absorbed by your body, and is often recommended if your folate levels are low.

No matter how you get this vitamin, it’s important you get enough of it so your body can feel its best. Here, experts share all the positive effects folic acid has on your health, who should take a folic acid supplement, and who should stick to getting folate from only food.

First, how much folic acid do you need per day?

The average adult should get 400 micrograms DFE (dietary folate equivalent) or 240 micrograms of folic acid from supplements and fortified foods per day, according to the National Institutes of Health (NIH).

Tip: DFE reflects the higher absorption of folic acid over folate naturally present in food. For reference,1 microgram of folate from food is equivalent to 0.6 micrograms of folic acid from supplements and fortified foods.

5 health benefits of folic acid

1. It can prevent birth defects in pregnancy

When you’re pregnant, folic acid helps your baby’s neural tube—what eventually becomes their brain and spine—grow.

“Folic acid supports the production of nucleotides,” which are the basic building blocks of RNA and DNA, says William Li, MD, author of ‌Eat to Beat Your Diet: Burn Fat, Heal Your Metabolism, and Live Longer‌‌. Nucleotides help form the central nervous system in a developing embryo, he adds.‌

That means, getting enough “folic acid is essential for preventing major birth defects of your baby’s brain and spine, known as neural tube defects, or NTDs,” says Stephanie Hack, MD, FACOG, a board-certified OB/GYN and founder of Lady Parts Doctor. Neural tube birth defects can cause serious medical problems in babies including:

• Cleft palate (an opening or split in the roof of the mouth that happens when tissue doesn’t join together completely)
• Spina bifida (a condition that affects the spine and may cause physical and/or intellectual disabilities)
• Brain damage

So how much folic acid should you take if you’re pregnant or planning to become pregnant? “The CDC recommends taking about 400 micrograms of folic acid (or 600 micrograms DFE) every day to help prevent birth defects,” says Dr. Hack.

Eating naturally folate-rich foods (more on this later) can also help you get the amount you need during pregnancy. Many breads, pastas, and cereals are fortified with folic acid, so eating these can also help you meet your daily target.

That said, it’s pretty hard to get 400 micrograms of folate through diet alone. That’s where prenatal vitamins come in handy. They’re formulated with just the right amount of folic acid for pregnant people. And if you’re planning to become pregnant, start taking a folic acid supplement 12 weeks before conceiving, says Dr. Hack. This is helpful because neural tube defects often happen early in pregnancy, sometimes before you even know you’re expecting, she adds.

“The CDC recommends taking about 400 micrograms of folic acid (or 600 DFE) every day to prevent birth defects.”—Stephanie Hack, MD, OB/GYN

2. It can treat a folate deficiency

While most people get enough folate (especially in countries like the U.S. where foods like cereals and pastas are fortified with folic acid), certain groups are still susceptible to folate deficiency.

People with alcohol use disorder, inflammatory bowel disease (IBD), and celiac disease can all have lower levels of folic acid, per Mount Sinai. These conditions can mess with your body’s ability to absorb certain vitamins and nutrients.

People with an MTHFR gene variant may also be more prone to a folate deficiency. The MTHFR gene is essential for making the MTHFR protein—a type of protein that helps your body absorb folate, according to the National Library of Medicine. So if you have a mutation in an MTHFR gene, your body may not be able to process folate very well.

People taking certain medications may also have low levels of folic acid. Examples of medicines that can interfere with your body’s absorption of folate include the following, per Mount Sinai:

• Antacids, used to treat heartburn
• H2 blockers, used to reduce stomach acid, including cimetidine (Tagamet), famotidine (Pepcid), and ranitidine (Zantac)
• Proton pump inhibitors, used to reduce stomach acid, including someprazole (Nexium), lansoprazole (Prevacid), omeprazole (Prilosec), and rabeprazole (Aciphex)
• Bile acid sequestrants, used to lower cholesterol, including colestipol (Colestid), cholestyramine (Questran), and colsevelam (Welchol)
• Anti-seizure medications, including phenobarbital, primidone (Mysoline), and carbamazepine (Tegretol)
• Nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen (Advil, Motrin) and naproxen (Aleve)
• Sulfasalazine (Azulfidine), used to treat inflammatory bowel disease (IBD) and rheumatoid arthritis (RA)
• Triamterene (Dyrenium), a diuretic (water pill)
• Cycloserine, an antibiotic
• Pyrimethamine (Daraprim), used to prevent and treat malaria and to treat toxoplasmosis
• Trimethoprim, an antibiotic used to treat urinary tract infections

What are the symptoms of a folic acid deficiency?

If your folic acid levels are lacking, it can show up in your health. Folic acid deficiency can lead to the following, per Mount Sinai:

• Poor growth (in infants and children)
• Tongue inflammation
• Gingivitis
• Loss of appetite
• Shortness of breath
• Diarrhea
• Irritability
• Forgetfulness
• Mental sluggishness

3. It supports your heart health

Folic acid is also important for your heart health. “It helps your body break down an amino acid called homocysteine,” says Dr. Li. When homocysteine levels get too high, it can damage your endothelium—or the lining of your blood vessels. Over time, this can cause blockages that lead to serious heart problems like stroke, adds Dr. Li.

While there’s no concrete evidence that high amounts of homocysteine cause heart disease, there are some studies to suggest that people with elevated homocysteine levels are more than twice as likely to have a stroke than those with healthy levels, and are at a higher risk of heart disease overall, per Mount Sinai.

Either way, getting enough folic acid is a safe bet when it comes to lowering harmful levels of homocysteine and protecting your heart. Try to fill your diet with folic-acid rich foods. And if you have a history of heart problems, ask your doctor whether you could benefit from taking a vitamin B supplement.

4. It may help lower your cancer risk

A diet rich in folic acid might be protective against some forms of cancer, including stomach, breast, cervical, pancreatic, and colorectal cancer, according to Mount Sinai.

The reverse may be true, too: “Low folate levels in the body are associated with an increased risk of cancer,” says Dr. Li, citing an August 2018 review in Current Nutrition Reports.

While scientists are still unsure why folic acid has this anti-cancer effect, some think it might relate “to folate’s involvement with the proper synthesis of DNA,” Dr. Li says. DNA is basically the “genetic code” or blueprint for the proper development and functioning of your body. So if something goes wrong when making DNA, mutations can happen, which can sometimes lead to cancer.

Still, there’s no concrete data that taking folic acid supplements prevents cancer, per Mount Sinai. The best way to reduce your cancer risk and stay healthy overall is by eating a balanced diet with folic acid-rich foods, and by seeing your doctor regularly for any recommended cancer screenings based on your age, family history, and current health.

5. It may help with depression

According to the NIH, people with low blood levels of folate are more likely to have depression. A December 2017 meta-analysis in the Journal of Psychiatric Research also found that people with depression may have lower levels of folate in their blood than those without depression. This can affect your treatment, too, as people with low folate levels may not respond as well to antidepressants compared to people with healthy folate levels, per the NIH.

This means getting enough folate may help support your mental health and possibly reduce the symptoms of depression, including suicidality. In fact, a large-scale September 2022 study in JAMA Psychiatry found that taking 1 milligram of folic acid per day (which is considered the upper tolerable limit for adults) was associated with lower rates of suicide and self-harm attempts in more than 850,000 study participants.

While these are promising findings, the relationship between folic acid and depression is still not fully understood. For example, it’s unclear whether a decreased appetite (a possible symptom of depression) leads to folate deficiency or whether folate deficiency contributes to depression, says Dr. Hack.

Researchers do have some preliminary theories about this connection, though. One is that “folic acid is needed by the brain to produce neurotransmitters such as serotonin and dopamine,” says Dr. Li. Because serotonin and dopamine both play an important role in mood, increasing them may reduce the symptoms of depression, he notes.

That said, other studies have found that taking folic acid is no better than a placebo when it comes to relieving depression, according to Mount Sinai.

The bottom line? There’s no guarantee folic acid supplements alone will treat your depression symptoms. Talk to your doctor before trying them, and if they give the OK, add it to your treatment plan alongside clinically proven methods like therapy and medication.

Dietary sources of folic acid

For most adults (with the exception of people who are pregnant or those trying to become pregnant), it’s best to get all the folate you need from whole foods. The good news? Lots of foods are naturally rich in folate, or are fortified with folic acid, so it’s likely you’ll get enough when eating a balanced diet.

Some foods naturally high in folate include the following, per the National Institutes of Health (NIH):

• Beef liver
• Vegetables (especially asparagus, brussels sprouts, and dark green leafy vegetables like spinach and mustard greens)
• Fruits and fruit juices (especially oranges and orange juice)
• Nuts, beans, and peas (like peanuts, black-eyed peas, and kidney beans)

Folic acid is also added to the following foods, per the NIH:

• Enriched bread, flour, cornmeal, pasta, and rice
• Fortified breakfast cereals
• Fortified corn masa flour (used to make corn tortillas and tamales, for example)

Who should take folic acid supplements? 

While most people should be able to get enough folic acid from their diets, some groups, like the following, may benefit from taking a supplement.

• People who are pregnant or plan to conceive: Start taking prenatals with folic acid three months before you plan to get pregnant, and aim for 400 micrograms per day, says Dr. Hack. If you’re at a higher risk of having a baby with neural tube defects (because you have a seizure disorder or had other babies with neural tube defects), 4,000 micrograms per day is recommended, she adds. But always talk to your doctor first about proper dosage.
• People with high blood levels of homocysteine: If your blood work shows you have high levels of homocysteine, taking a folic acid supplement may reduce your risk of heart problems and lower the amino acid to healthier levels in your blood, says Dr. Li. The recommended dose in this case is 400 micrograms, he adds.
• People at risk of folate deficiency: This includes people with alcohol use disorder, severe malnutrition, inflammatory bowel disease (IBD), celiac disease, or the MTHFR gene variant, says Dr. Hack.
• People with depression: If your doctor agrees, taking a folic acid supplement alongside other treatments, like antidepressants and lifestyle changes, could help reduce your symptoms. But keep in mind researchers are still unclear about how much folic acid to take to relieve depression, says Dr. Li.

No matter what your situation, always check with your doctor before starting a new supplement because some may negatively interact with other medications or cause side effects. Your doctor can also help decide the right dosage for you.

Who should not take folic acid supplements?

For some people, taking a folic acid supplement might do more harm than good. Use caution if you belong to one of the following groups, and always talk to your doctor before starting any new supplement:

• People allergic to folic acid: It’s rare, but possible, to have a folic acid allergy. Signs of an allergic reaction include skin rash, itching, redness, and in severe cases, difficulty breathing, per the Mayo Clinic. If you have any of these symptoms after taking a supplement, stop taking it and see your doctor as soon as possible.
• People who take certain medications: Sometimes folic acid can interfere with certain medications and make them less effective. For example, “people taking the seizure medication Dilantin (phenytoin) should talk to their doctor before taking folic acid, because it could lower the drug concentration in your blood, making it less effective,” says Dr. Li. The same goes for other anticonvulsant medicines like fosphenytoin (Cerebyx) and primidone (Mysoline), per the Mayo Clinic. Folic acid can also interfere with methotrexate to treat cancer, per Mount Sinai, and decrease the effectiveness of barbiturates and the anti-malaria drug pyrimethamine (Daraprim), per the Mayo Clinic.

Is it possible to take too much folic acid?

When you take the daily recommended dosage, folic acid is generally safe. But if you take too much (more than 1,000 micrograms, or the daily upper limit), you can have negative side effects. Though rare, high doses of folic acid can cause the following symptoms, per Mount Sinai:

• Stomach problems
• Sleep problems
• Skin reactions
• Confusion
• Loss of appetite
• Nausea
• In severe cases, seizures

“High doses of folic acid can also mask symptoms of a vitamin B12 deficiency,” says Dr. Hack. A long-term vitamin B12 deficiency can be dangerous, as it can lead to permanent damage of the brain, spinal cord, and nerves, according to the NIH.

You can usually avoid this problem by taking a supplement with 100 percent of the daily value of both folic acid and vitamin B12, per the Mayo Clinic.

To be safe, always talk to your doctor before taking more than 800 micrograms of folic acid.