Folate deficiency means your body doesn’t have enough folate (vitamin B9) to make healthy red blood cells. It’s uncommon in the U.S. because grains are fortified, but it does happen, and it matters more during pregnancy.

The short version

  • Main symptoms: tiredness, weakness, trouble concentrating, headaches, a racing heart, shortness of breath, and a sore tongue or mouth sores.
  • Most common causes: a diet low in folate, heavy drinking, digestive conditions like celiac disease, certain medicines, and the higher needs of pregnancy.
  • Diagnosis: a blood test. Your provider will usually check vitamin B12 too, because low B12 causes nearly identical anemia.
  • Treatment: usually folic acid plus fixing the underlying cause. Anemia from low folate most often improves within 3 to 6 months, according to MedlinePlus.
  • Prevention: a varied diet with folate-rich and fortified foods, plus 400 mcg of folic acid a day for anyone who could become pregnant.

Symptoms: what low folate feels like

Most symptoms come from folate-deficiency anemia. Without enough folate, your body makes red blood cells that are too large and don’t carry oxygen well. The NIH lists these signs:

From the anemia

  • Tiredness and weakness
  • Trouble concentrating
  • Irritability
  • Headache
  • A racing or pounding heartbeat
  • Shortness of breath

In the mouth and on the body

  • A sore tongue and shallow sores inside the mouth
  • Changes in the color of your skin, hair, or fingernails
  • Digestive symptoms

These symptoms come on gradually and overlap with many other conditions, including iron-deficiency anemia, B12 deficiency, thyroid problems, and the normal exhaustion of pregnancy or a new baby. That’s why a blood test, not a symptom checklist, is the way to know.

Causes and who’s at risk

Folate deficiency rarely happens alone. It usually comes with other nutrient shortages, because the same things that lower folate tend to lower other nutrients too, according to the NIH. The groups most likely to run low:

Who Why
People who drink heavily Alcohol lowers folate absorption, speeds its breakdown, and increases how much is lost in urine. Even 8 ounces of wine a day for two weeks lowered folate levels in one study, though not to deficient levels.
Women who could become pregnant Some don’t get enough even with supplements. Among women ages 19 to 30, 17% fall short; among girls 14 to 18, 19% do.
Pregnant women Needs rise from 400 to 600 mcg DFE a day, which can be hard to meet with food alone.
People with celiac disease, inflammatory bowel disease, or past stomach surgery These conditions make it harder to absorb folate. About 20% to 60% of people with inflammatory bowel disease are folate deficient.
People taking certain medicines Methotrexate, some anti-seizure medicines (phenytoin, carbamazepine, valproate), and sulfasalazine can lower folate levels.

A common MTHFR gene variant makes the body slightly less efficient at converting folate, but the CDC says people with it can still process folic acid normally, and how much folic acid you get matters more than your genes.

How it’s diagnosed

A simple blood draw can show whether you’re low. Your provider may order one or more of these tests, described by the NIH:

Test What it shows
Complete blood count (CBC) Whether you have anemia and whether your red blood cells are larger than normal, a clue that folate or B12 is low
Serum folate Your recent intake over the past few days. Above 3 ng/mL is generally considered adequate.
Red blood cell folate Your longer-term folate status over the past few months. Above 140 ng/mL is generally considered adequate.
Homocysteine A substance that builds up when folate or B12 is low. Above about 16 µmol/L is considered high.
Vitamin B12 Rules out B12 deficiency, which causes the same type of anemia

Lab ranges vary, so go by the range printed on your own results and your provider’s read of them.

Why the B12 check matters. Folic acid can fix the anemia caused by low B12 while the nerve damage from B12 deficiency keeps progressing. Treating with folic acid before ruling out B12 can delay the right diagnosis. That’s the main reason not to self-treat suspected folate deficiency with high-dose supplements.

Treatment and prevention

Treatment usually has two parts: replacing the folate and fixing why it ran low. Your provider will recommend a folic acid dose based on your results, and look at the cause, such as diet, alcohol, a digestive condition, or a medicine. Folate-deficiency anemia most often responds well within 3 to 6 months once the underlying cause is treated, according to MedlinePlus.

If a medicine you need is lowering your folate, don’t stop it on your own. Some anti-seizure medicines interact with folic acid in both directions, so changes should be made with your doctor.

Prevention for most people is simply a varied diet:

  • Dark leafy greens, beans and peas, asparagus, avocado, and oranges for natural folate
  • Enriched breads, cereals, pasta, and rice for folic acid
  • For anyone who could become pregnant, 400 mcg of folic acid a day from a vitamin or fortified foods, as the CDC recommends

See our guide to foods high in folate for amounts per serving.

Folate deficiency and pregnancy

Pregnancy is when low folate matters most, for two reasons.

Birth defects. Low folate early in pregnancy raises the risk of neural tube defects such as spina bifida and anencephaly. The neural tube closes 21 to 28 days after conception, so folate needs to be in place before many women know they’re pregnant. That’s why the CDC recommends 400 mcg of folic acid daily for anyone who could become pregnant, starting at least one month before pregnancy.

Other pregnancy outcomes. Low folate in pregnancy has also been linked to low birth weight, preterm birth, and slower growth of the baby, according to the NIH. These studies show a link rather than proof of cause, but they add to the reasons to keep folate up throughout pregnancy, when your daily need rises to 600 mcg DFE.

If you’re pregnant and have symptoms of anemia, mention it at your next visit. Your blood is usually checked for anemia during pregnancy, according to ACOG, and the cause can be low iron, low folate, or both.

Related reading

Sources

This article is for general information and is not a substitute for advice from your health care provider.