Can I get too much folate or folic acid?

There isn’t any danger in consuming excessive amounts of naturally occurring folate in foods. However, consuming too much folic acid, either through supplements or fortified foods, can be harmful for individuals who are deficient in vitamin B12.

A vitamin B12 deficiency can cause anemia and, more dangerous, crippling and irreversible nerve damage. Too much folate in the diet masks the symptoms of B12 deficiency anemia. Though the folate can correct anemia, the nerve damage due to the vitamin B12 deficiency persists. This delays a proper diagnosis and corrective therapy with vitamin B12. By the time the person is given the vitamin B12, irreversible nerve damage may have occurred.

While low folate intake may be associated with increased cancer risk, studies suggest that folate consumption double the DRI or even higher may increase the risk for cancer.

When it comes to folic acid, some is essential, but more may not be better.
Dariush Mozaffarian, MD
Internal Medicine
Beware of getting too much folic acid from supplements and fortified foods. Most multivitamins contain 400 micrograms (mcg), but many fortified breakfast cereals also contain that much. Add a few other enriched grain products (10 pretzels adds 172 mcg, and a cup of spaghetti, 166 mcg) and you're over your daily limit. If you take a daily multivitamin, avoid foods fortified with 300 to 400 mcg of folic acid.
Foliate is the form of vitamin B9 found in natural food sources. You can't get too much folate. However, it's possible to take too much folic acid, the manmade form found in supplements and fortified foods. Doing so can cause stomach problems, trouble sleeping and skin reactions.

Certain people should be especially careful about taking folic acid, including those who:
  • take anticonvulsant medications. High levels of folic acid can provoke seizures in people on these drugs.
  • are being treated for cancer. Folic acid may raise the amounts of certain chemotherapy drugs to potentially dangerous levels while interfering with the effectiveness of other cancer treatments.
  • are on antibiotics. Taking folic acid supplements at the same time as certain antibiotics may interfere with the body's absorption of the antibiotics and their effectiveness.
  • have a vitamin B12 deficiency. Folic acid may trigger serious symptoms, including potentially permanent nerve damage.
Talk to your doctor before taking folic acid or any dietary supplement.
You can't get too much folate from foods that naturally have folate. But it is possible for some people to get too much folic acid. Taking more than 1,000 mcg of folic acid a day may cause nerve damage in people who do not have enough vitamin B12 in their bodies. People at risk for not having enough vitamin B12 include:
  • People who don't eat meat, eggs, or dairy products (vegans) People ages 50 years and older
This answer is based on source information from the National Women's Health Information Center.
Kevin W. Windom, MD
OBGYN (Obstetrics & Gynecology)
No. Folate is a B vitamin and all B vitamins are water soluble. This means that if you take too much of a B vitamin then your kidneys will filter out the excess and you will "pee it out". People who have low B12 levels can have toxicity to excess folic acid -- but this is rarely seen.

Continue Learning about Vitamin B9

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.