When you might need a folate blood test

Folate, otherwise known as vitamin B9, is an essential nutrient we get from food. Our bodies need folate to make DNA and to break down certain chemicals in the body.

While everyone should get enough folate, it's essential for pregnant women or those who might become pregnant to have healthy folate levels to prevent birth defects (Bailey, 2015). Getting enough folate is vital during the first trimester of pregnancy when the spinal cord is forming (Chitayat, 2016). 

Several studies, including one  back in 1982, showed folic acid supplementation could lower the risk of neural tube defects. The U.S. Food and Drug Administration (FDA) required companies to add folic acid to certain foods to ensure people were getting adequate amounts (Czeizel, 1992; Crider, 2011). 

Let’s take a look at folate and how it works with other vitamins in the body.

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Folate works closely with cobalamin—more commonly known as vitamin B12—to make the building blocks for DNA. 

To produce red blood cells, healthy levels of folate and vitamin B12 are needed. A deficiency of these vitamins can lead to megaloblastic anemia, a condition characterized by large, immature red blood cells (Socha, 2020). 

If you suspect you may have a vitamin deficiency, getting a folate blood test or your B12 levels checked is the first step in the process.

As we mentioned, most of us get folate from food. When we eat foods that contain folate, our bodies absorb and use it to make DNA. Our bodies also store leftover folate in places like the liver, tissues, and blood (Achebe, 2017). 

What's considered healthy folate levels can vary. The National Institutes of Health (NIH) suggests a serum folate level above 3 ng/mL, although some healthcare experts consider a serum level greater than 4 ng/mL to be normal (NIH, 2020). Levels between 2–4 ng/mL are borderline, while those below 2 ng/mL are considered low (Achebe, 2017). 

If you suspect you might have a deficiency, a blood test called serum folate can check the levels in your blood. 

Another blood test that can check for a folate deficiency is called RBC folate. This test isn't used as often and can be challenging for the lab to run, but it's better at showing folate levels long-term. RBC folate is also dependent on vitamin B12 levels (Bailey, 2015).

Many people go through life without ever having their folate levels checked. It's not a part of a standard lab test that you have drawn at the hospital or clinic, and folate deficiencies are pretty rare in the United States (NIH, 2020).

A healthcare provider might do a folate blood test if you’re pregnant or trying to become so. Many providers recommend folic acid supplements (usually in the form of a prenatal vitamin) without testing folate levels (Achebe, 2017). 

You may also need a folate blood test if you have symptoms of anemia, which often results from not enough folate or vitamin B12. In this case, a healthcare provider will likely check both folate and B12 levels to determine which one is low. If one or both are low, you may be prescribed supplements (Socha, 2020).

Folate is an essential nutrient for us, so how do we make sure we're getting enough? 

Folate is present in many foods, such as green vegetables, dairy products, and meat. Grain products like bread, rice, and cereal are also fortified with folic acid to prevent deficiencies (Bailey, 2015). 

For people who can't get enough folate from food alone, there are folic acid supplements available. What’s the difference between folate and folic acid? Folate is found naturally in food, whereas folic acid is a synthetic version of the vitamin. All supplements and fortified food contain folic acid, which is absorbed better than folate (Bailey, 2015).  

The NIH recommends at least 400 mcg of folate daily for most adults. People who are pregnant, might become pregnant, or are breastfeeding should have around 600 mcg (NIH, 2020). 

Folate deficiencies aren't prevalent in countries that fortify foods, but still happen. Malnutrition, not being able to absorb nutrients properly, or medications that interact with folate are all things that could lead to a deficiency.

Chronic alcohol consumption can lead to low folate levels due to malnutrition and poor absorption. Many times, alcoholic beverages replace nutrient-rich food. People who overuse alcohol might not eat enough folate-rich food to keep their serum levels at a healthy level. Also, chronic alcohol use decreases the amount of folate your gut absorbs. In other words, there's less folate coming in and more going out (Medici, 2013).

Conditions that cause inflammation of the digestive system can also lead to folate malabsorption. These include celiac disease, ulcerative colitis, and Crohn's disease (Martin-Masot, 2019).

Medications that can lower serum folate levels include methotrexate, sulfasalazine, and anti-seizure medicine. Some people taking these medications also take folic acid supplements to minimize side effects. Do not take folic acid supplements unless directed as too much can interact with the medication's intended use (Friedman, 2019; Linneback, 2011).

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Current version

May 05, 2021

Written by

Hope Chang, PharmD

Fact checked by

Yael Cooperman, MD

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About the medical reviewer

Yael Cooperman, MD, Ro

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.