Some research suggests people with cancer may have an increased risk of folic acid deficiency, which may be due to cancer-related complications and treatments.

Folic acid, also called folate or vitamin B9, is an essential nutrient that supports various functions in the body.

Folic acid deficiency may lead to symptoms, such as a painful or red tongue, and without treatment, may lead to complications.

This article explains whether cancer can cause a folic acid deficiency, the symptoms and other common causes of folic acid deficiency, and when to contact a doctor.

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According to a 2018 study, people with cancer may have an increased risk of folic acid deficiency, although it is not common.

Out of 960 people receiving cancer treatment in a hospital, 6.8%, or 69 people, had folic acid deficiency. Most of these people were anemic.

In 28 of the 69 people, researchers identified a risk factor for folic acid deficiency. In most of those 28 people, the risk factor was medications. The other risk factors were:

  • malabsorption or malnutrition
  • hemolysis, which occurs when the destruction of red blood cells happens faster than the body can replace them
  • hemodialysis, a treatment for filtering the blood when the kidneys cannot

The study suggests rates of folic acid deficiency may be higher in people with cancer compared to those without cancer. This may be due to coexisting health conditions and related medical treatments in people with advanced cancer.

There is no clear evidence any specific type of cancer causes a folic acid deficiency.

Can folic acid deficiency cause cancer?

Researchers are still investigating the link between cancer and folic acid deficiency. It is unclear whether folic acid deficiency is a cause or result of certain cancers.

A 2017 review suggests maternal folic acid supplementation during pregnancy may reduce the risk of childhood leukemia in their offspring.

Similarly, a 2024 article suggests folic acid may have protective effects against certain cancers due to various mechanisms, including antioxidant properties and DNA repair.

However, the article also highlights evidence suggesting high intake of folic acid may increase the risk of certain cancers, as it may promote the growth of cancer cells. These include cancers of the:

Further research is necessary to fully understand the link between folic acid and cancer.

Folic acid deficiency can occur for many reasons other than cancer. For example, a person who does not get enough folic acid in their diet may develop a folic acid deficiency.

Folic acid deficiency can also occur in pregnancy, as people require higher levels of folic acid during pregnancy and breastfeeding. Alcohol use disorder (AUD) is also a significant cause of folic acid deficiency.

Other potential causes of folic acid deficiency include:

Risk factors for folic acid deficiency

Risk factors for folic acid deficiency include:

  • malabsorption, which means the digestive system is unable to absorb nutrients properly
  • pancreatic insufficiency, in which the pancreas does not make enough digestive enzymes to support proper digestion
  • end stage kidney disease with hemodialysis
  • malnutrition
  • hemolytic anemia, a blood condition which causes a lack of red blood cells

A person’s symptoms may indicate the underlying cause of their deficiency. For example, high alcohol intake may lead a doctor to consider AUD as a cause.

However, other signs of folic acid deficiency may include a sore, red tongue and neurological symptoms, such as depression or memory loss.

If people have concerns about their folic acid intake, they can contact a doctor.

A doctor will take a medical history and carry out a physical exam to check symptoms and perform a blood test to check folate levels. People may also have other tests to check for any underlying causes.

If someone has a folic acid deficiency, a doctor may recommend taking a folic acid supplement and increasing folic acid in the diet.

People may also require B12 supplementation, as the two deficiencies can co-occur and cause similar symptoms.

If people have cancer and think they may have a folic acid deficiency, it is important to speak with a doctor. Increased intake or supplementation of folic acid may have risks for people with certain types of cancer or cancer risk factors.

Some research suggests people with cancer may have a higher risk of folic acid deficiency. Factors relating to cancer and cancer treatments, such as difficulty eating a balanced diet or taking certain medications, may link to folic acid deficiency in some people.

Many factors can cause folic acid deficiency, including a lack of folic acid in the diet, pregnancy, celiac disease, and alcohol use disorder.

If people have symptoms of folic acid deficiency, they should contact a doctor. If people have a folic acid deficiency, a doctor may recommend folic acid supplementation or dietary changes.