What Is a Folate Deficiency?

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A folate deficiency is a lack of vitamin B9 (folate). Folate is a water-soluble vitamin that can only be taken into the body through foods and supplements. The body uses folate to create and repair DNA (the genetic material inside cells) and to produce red blood cells, which carry oxygen throughout the body. 

This article will discuss the symptoms, causes, diagnosis, and treatment for a folate deficiency. 

Foods high in vitamin B9. Healthy food, sources of folic acid.

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Folate Deficiency Symptoms

The early signs of a folate deficiency can be subtle, and it’s common for it to go undiagnosed. Signs and symptoms of a folate deficiency may include:

  • Fatigue
  • Mouth sores
  • Cracked sores on one or both corners of the mouth
  • Smooth and tender tongue
  • Irritability
  • Pale skin

When left untreated, more symptoms can develop, and they may become more severe. Less common and potentially severe symptoms of a folate deficiency may include:

  • Trouble thinking and cognitive decline
  • Psychosis
  • Depression
  • Erectile dysfunction

Causes of Folate Deficiencies

Folate is a water-soluble vitamin. This means it’s absorbed and transported in water. If you consume more water-soluble vitamins than your body can use in a day, your kidneys filter out the extra in urine.

Unlike other types of water-soluble vitamins, a small amount of folate can be stored in the liver. A deficiency could develop in weeks to months on a diet that doesn't provide folate. 

Here are potential causes of a folate deficiency:


If you don’t consume enough folate from your diet, you can develop a deficiency. Folate is found in fruits, vegetables, nuts, eggs, and some types of seafood. Some foods are fortified with a synthetic form of folate, called folic acid.

In addition, the heat used during cooking may destroy some of the folate and decrease the amount provided in your diet. Folic acid is added to grain products like flour, bread, cereal, pasta, rice, and cornmeal. 

Digestive Diseases

Medical conditions that affect the digestive system can interfere with your body’s ability to digest and absorb folate. These can include:

  • Celiac disease: An autoimmune disease triggered by gluten in food
  • Crohn’s disease: An inflammatory bowel disease that can affect any part of the digestive tract
  • Ulcerative colitis: An inflammatory bowel disease of the large intestine (colon)
  • Bowel surgery

Kidney Failure and Dialysis

People with end-stage renal (kidney) disease who receive regular dialysis have a higher risk of nutrient deficiencies. Dialysis helps to replace kidney function by filtering out excess nutrients, toxins, and other components from the blood. But sometimes too much of certain nutrients can be taken out and cause a deficiency.

People undergoing dialysis treatments should be monitored for deficiencies and take additional vitamins as needed. 


Before the body uses folate, it converts folate into an active form called methylfolate. Some genetic mutations, like the MTHFR gene, can interfere with converting folic acid into its active form.

This means that if you have the MTHFR gene, you could develop a folate deficiency even if you’re eating foods fortified with folic acid or taking a folic acid supplement.

Excessive Alcohol Intake

Drinking too much alcohol can interfere with digestion and absorption of nutrients. Research shows that folate deficiencies are common among people with alcohol use disorder.

Medication Side Effects

Some medications may lead to a folate deficiency, such as:

  • Azulfidine (sulfasalazine)
  • Bactrim (trimethoprim-sulfamethoxazole)
  • Dilantin (phenytoin)
  • Trexall (methotrexate)


Folate deficiencies are diagnosed with a blood test to assess folate levels and the health of red blood cells. If your healthcare provider suspects a folate deficiency, they may order blood tests like:

  • Serum folate levels
  • Complete blood count (CBC)

It’s common for folate levels to be checked during pregnancy to monitor for a deficiency since it can lead to complications. 


If left untreated, a folate deficiency in pregnancy can lead to complications like:

  • Megaloblastic anemia: A condition in which red blood cells become unusually large and abnormal in structure that makes them work less efficiently
  • Pancytopenia: A condition causing low levels of red blood cells, white blood cells, and platelets in the blood
  • Neural tube defects: A condition in which the baby’s neural tube or spinal cord doesn’t completely close, which leaves the nerves exposed

Neural Tube Defects

Neural tube defects are skull birth defects and defects along the lower spine. Three types are anencephaly (parts of the brain and skull do not form), encephalocele (sac-like protrusion of the brain and its membranes), and spina bifida (vertebrae do not form correctly around the spinal cord). 


Treatment for a folate deficiency includes increasing intake of folate or folic acid. People without the MTHFR gene mutation can meet their needs with either folate or folic acid in supplements or foods.

But people who have the mutation should focus on consuming folate foods or specific types of folate supplements (since they can't convert folic acid into its active form).

Since the neural tube develops in the first few weeks of pregnancy (before most people know they’re pregnant), it’s recommended that all people who are capable of becoming pregnant take a folate supplement.

It’s recommended for most people to consume 400 micrograms of folate per day.

Some of the foods high in folate include:

  • Dark, leafy green vegetables (such as spinach, kale, and romaine lettuce)
  • Asparagus
  • Broccoli
  • Brussels sprouts
  • Oranges
  • Bananas
  • Berries
  • Grapes
  • Beans
  • Sunflower seeds
  • Peanuts
  • Eggs
  • Liver
  • Crab

Folic acid is added to fortified grains like:

  • Ready-to-eat breakfast cereal
  • Bread
  • Pasta
  • Rice
  • Cornbread
  • Flour


Folate deficiency develops when there isn’t enough vitamin B9 in the body. The body uses folate to repair and replicate DNA and create red blood cells. A folate deficiency can be caused by a lack of folate in the diet, medical conditions, drinking too much alcohol, gene mutations, and side effects of medications.

The deficiency can be treated by increasing folate or folic acid intake through supplements and foods. 

A Word From Verywell 

At first, it can be difficult to notice the symptoms of a folate deficiency. But once you’re aware of it, the deficiency can be simple to treat through increasing foods and supplements. If you suspect you have a nutrient deficiency, it’s best to talk with your healthcare provider to confirm the diagnosis. 

You may be able to prevent a folate deficiency by focusing on eating a variety of fresh, nutritious foods high in folate.

17 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Ashley Braun, MPH, RD
Ashley Braun, MPH, RD, is a registered dietitian and public health professional with over 5 years of experience educating people on health-related topics using evidence-based information. Her experience includes educating on a wide range of conditions, including diabetes, heart disease, HIV, neurological conditions, and more.