Understanding Which Anemia Is Caused by Folic Acid Deficiency?

October 1, 2025 •

4 min read

According to the Centers for Disease Control and Prevention (CDC), many countries have implemented grain fortification to significantly reduce the prevalence of folate deficiency. A deficiency in this essential B vitamin leads to a specific type of blood disorder, so knowing which anemia is caused by folic acid deficiency is crucial for proper treatment and prevention.

Quick Summary

Folic acid deficiency leads to megaloblastic anemia, a condition where the body produces abnormally large, immature red blood cells that cannot function correctly. The deficiency impairs DNA synthesis, affecting all blood cell lines and causing symptoms like fatigue and paleness.

Key Points

Megaloblastic Anemia: This is the specific type of anemia caused by a folic acid (vitamin B9) deficiency, resulting in abnormally large and immature red blood cells.
Impaired DNA Synthesis: The root cause of megaloblastic anemia is impaired DNA synthesis in red blood cell precursors due to insufficient folic acid.
Common Symptoms: Signs include fatigue, paleness, a sore tongue, and gastrointestinal issues like diarrhea.
Diagnosis is Critical: Blood tests are necessary to confirm folate deficiency and, importantly, to rule out a concurrent vitamin B12 deficiency, which can cause permanent neurological damage if not correctly treated.
Supplementation is Standard Treatment: Most cases are treated with oral folic acid supplements and dietary improvements, leading to symptom resolution within months.
Prevention is Possible: Ensuring a diet rich in leafy greens, fortified cereals, and supplementing, especially for at-risk groups like pregnant women, can prevent the deficiency.

The Specific Type: Megaloblastic Anemia

Folic acid, or vitamin B9, is vital for the production of red blood cells and for synthesizing and repairing DNA. Without adequate levels of this vitamin, the body's ability to produce healthy, mature red blood cells is impaired. The condition resulting from this deficiency is known as megaloblastic anemia.

In megaloblastic anemia, the process of DNA synthesis is disrupted, causing the red blood cell precursors in the bone marrow to grow larger than normal. These large, immature cells, called megaloblasts, fail to divide and mature correctly. The large, misshapen red blood cells that are eventually released into the bloodstream are fewer in number, inefficient at carrying oxygen, and have a shorter lifespan than healthy cells. This reduced oxygen-carrying capacity throughout the body is what leads to the symptoms associated with anemia.

Causes of Folic Acid Deficiency

While dietary inadequacy is a primary cause, especially in people with an unbalanced diet or excessive alcohol consumption, several other factors can contribute to a folic acid deficiency.

Inadequate Dietary Intake: People who do not consume enough folate-rich foods, such as leafy green vegetables, citrus fruits, and fortified cereals, can develop a deficiency.
Malabsorption Issues: Certain medical conditions affecting the digestive tract, like celiac disease or Crohn's disease, can prevent the body from properly absorbing folate.
Increased Demand: The body's need for folate increases significantly during certain periods, such as pregnancy, lactation, and in conditions with high cell turnover like chronic hemolytic anemia.
Medications: Some drugs, including certain anti-seizure medications and methotrexate, can interfere with the absorption or metabolism of folate.
Excessive Alcohol Use: High alcohol consumption can hinder the body's ability to absorb and utilize folate effectively.

Common Symptoms of Megaloblastic Anemia

The symptoms of megaloblastic anemia often develop gradually and can be non-specific. They may be more severe the longer the condition goes untreated.

Fatigue and Weakness: The most common symptoms, caused by the reduced delivery of oxygen to the body's tissues.
Pale Skin: A noticeable paleness, or pallor, is a typical sign of anemia.
Sore and Red Tongue: Glossitis, or inflammation of the tongue, is a distinct oral symptom.
Gastrointestinal Issues: Patients may experience diarrhea, reduced appetite, and weight loss.
Irritability and Psychological Changes: Mood disturbances, including irritability and depression, can occur.
Other Physical Symptoms: Shortness of breath, dizziness, and heart palpitations can manifest as the body tries to compensate for the lack of oxygen.

Diagnosis and Treatment of Folate Deficiency Anemia

To diagnose folate deficiency anemia, a healthcare provider will typically perform a physical exam and order several blood tests. These tests are crucial for confirming the diagnosis and ruling out other conditions with similar symptoms, particularly vitamin B12 deficiency.

Key diagnostic tests include:

Complete Blood Count (CBC): Reveals larger than normal red blood cells, indicated by an elevated mean corpuscular volume (MCV).
Serum Folate Level: Measures the amount of folate in the blood, with low levels suggesting a deficiency.
Vitamin B12 Level: Essential to measure alongside folate, as B12 deficiency also causes megaloblastic anemia. Treating a B12 deficiency with folic acid alone can mask the anemia while allowing neurological damage to progress.
Methylmalonic Acid (MMA) and Homocysteine Levels: These markers can help differentiate between a folate and B12 deficiency. Homocysteine is elevated in both, but MMA is typically only elevated in B12 deficiency.

Treatment and Management

Treatment is straightforward and typically very effective, revolving around correcting the underlying deficiency.

Folic Acid Supplements: The primary treatment involves taking oral folic acid supplements, often for several months, until levels are restored.
Dietary Changes: Increasing the intake of folate-rich foods is recommended for long-term prevention.
Treating Underlying Conditions: If malabsorption or another medical condition is the cause, it must also be addressed.

Comparison of Folate Deficiency Anemia vs. Vitamin B12 Deficiency Anemia

Because both folate and vitamin B12 deficiencies can cause megaloblastic anemia, distinguishing between them is critical for proper treatment. The neurological complications associated with B12 deficiency require specific B12 supplementation.


Feature	Folic Acid Deficiency Anemia	Vitamin B12 Deficiency Anemia
Associated Symptoms	Fatigue, paleness, sore tongue, gastrointestinal issues.	Fatigue, paleness, sore tongue, neurological symptoms (pins and needles, memory issues).
Neurological Effects	Rare in isolated deficiency, but can occur.	Common and can be permanent if left untreated.
Diagnostic Markers	Low serum/RBC folate, elevated homocysteine, normal MMA.	Low serum B12, elevated homocysteine, elevated MMA.
Treatment	Folic acid supplements, dietary changes.	Vitamin B12 injections or high-dose oral supplements.
Masking Risk	Does not mask other deficiencies in the same way.	Anemia can be masked by high-dose folic acid, delaying diagnosis of neurological damage.

Prevention Strategies

Preventing folic acid deficiency is often more manageable than treating it. Following these strategies can help maintain adequate folate levels:

Maintain a Nutritious Diet: Consume plenty of natural folate sources, such as leafy greens, citrus fruits, beans, and lentils.
Choose Fortified Foods: Incorporate products fortified with folic acid, like enriched breads, cereals, and pasta.
Consider Supplements: For pregnant women or those planning to become pregnant, a daily folic acid supplement is highly recommended to prevent neural tube defects.
Limit Alcohol Intake: Reduce excessive alcohol consumption, which can interfere with folate absorption.
Monitor Medical Conditions: Individuals with malabsorption issues or those taking certain medications should be regularly monitored for folate levels by their healthcare provider.

Conclusion

Folic acid deficiency is a treatable condition that results in megaloblastic anemia, a blood disorder characterized by large, immature red blood cells. Symptoms like fatigue, paleness, and a sore tongue are key indicators. Proper diagnosis involves blood tests that measure folate and vitamin B12 levels, as differentiating between the two deficiencies is critical to prevent serious neurological complications. With the right treatment, which often includes oral folic acid supplements, most people can recover successfully and prevent future deficiencies. If you suspect you have any form of anemia, consulting a healthcare provider for an accurate diagnosis is essential for your long-term health and well-being. You can find more authoritative information from sources like the Cleveland Clinic to better understand the specifics of folate deficiency and its consequences.

Frequently Asked Questions

Megaloblastic anemia is a blood disorder where the bone marrow produces abnormally large, immature, and non-functional red blood cells due to impaired DNA synthesis, most commonly caused by deficiencies in folic acid or vitamin B12.

While both cause megaloblastic anemia, a key difference is that vitamin B12 deficiency can lead to distinct neurological symptoms like tingling in the hands and feet. Blood tests measuring folate, B12, and methylmalonic acid (MMA) help differentiate the two.

Adequate folic acid intake is crucial during early pregnancy to prevent serious birth defects of the baby's brain and spinal cord, known as neural tube defects, like spina bifida.

Yes, some people may have a folate deficiency and anemia without any noticeable symptoms, especially in the early stages. The condition may be discovered during routine lab tests.

Foods rich in natural folate include leafy green vegetables (spinach), citrus fruits, legumes (beans, peas), and liver. Many grain products like cereals, bread, and pasta are also fortified with folic acid.

Untreated folic acid deficiency can lead to various health complications, including heart issues, temporary infertility, certain cancers, and, during pregnancy, an increased risk of neural tube defects.

Yes, treating megaloblastic anemia with high-dose folic acid when a B12 deficiency is also present can correct the anemia but mask the underlying B12 issue, allowing potentially irreversible neurological damage to progress.