What are the side effects of having low folate? Understanding Deficiency Impacts

October 27, 2025 •

3 min read

The body stores only a small amount of folate, meaning a deficiency can develop within just a few months if intake is inadequate. Understanding what are the side effects of having low folate is crucial for identifying this potentially serious nutritional deficiency early and preventing long-term health complications.

Quick Summary

Low folate can lead to a range of health issues, including megaloblastic anemia, which causes fatigue and weakness, and more severe neurological and mood-related problems. Deficiency is particularly risky during pregnancy, increasing the likelihood of neural tube defects and other birth complications.

Key Points

Megaloblastic Anemia: Low folate impairs red blood cell production, causing fatigue, weakness, and paleness due to abnormally large, inefficient red blood cells.
Neurological and Mood Effects: Deficiency can cause headaches, irritability, difficulty concentrating, depression, and, in severe cases, confusion and dementia.
Increased Birth Defect Risk: Inadequate folate before and during early pregnancy can lead to serious neural tube defects in the fetus, such as spina bifida and anencephaly.
Elevated Homocysteine Levels: Low folate is linked to higher blood levels of homocysteine, an amino acid that can increase the risk of cardiovascular disease and stroke.
Oral and Digestive Issues: Folate deficiency can cause a sore, red tongue, mouth ulcers, diarrhea, and a loss of appetite.
Underlying Causes: The deficiency can be caused by poor diet, certain medications, alcohol use, and malabsorption disorders like celiac or Crohn's disease.
Supplementation is Crucial: Treatment typically involves increasing dietary intake of folate-rich foods and taking folic acid supplements to resolve symptoms and prevent complications.

What is Folate and Why Is It So Important?

Folate, also known as vitamin B9, is a water-soluble vitamin essential for producing new red blood cells, synthesizing and repairing DNA, and ensuring proper cell division. The body cannot produce folate and relies on dietary sources like leafy greens, fruits, and fortified grains. A lack of sufficient folate impairs these vital functions, leading to negative health effects.

Manifestations of Low Folate: Common Symptoms

Symptoms of folate deficiency can appear gradually and often relate to anemia due to folate's role in red blood cell production.

Fatigue and Weakness: Reduced oxygen transport due to fewer healthy red blood cells causes persistent tiredness and muscle weakness.
Pale Skin: A decreased red blood cell count can result in noticeable paleness.
Shortness of Breath and Palpitations: The heart may beat faster and breathing can become difficult as the body tries to compensate for reduced oxygen.
Neurological Signs: Headaches, dizziness, and irritability are common. Difficulty with concentration and memory can also occur.
Gastrointestinal Issues: Diarrhea, loss of appetite, and weight loss are possible digestive symptoms.
Oral Symptoms: A smooth, red, and tender tongue, along with mouth sores, are characteristic signs.

Major Complications and Health Risks of Low Folate

Prolonged folate deficiency can lead to more serious and lasting health issues beyond initial anemia-related symptoms.

Megaloblastic Anemia: This condition involves the production of large, immature red blood cells that cannot function effectively, further worsening fatigue and weakness.
Birth Defects: Folate is critical for fetal nervous system development. Deficiency during early pregnancy increases the risk of neural tube defects like spina bifida and anencephaly, as well as premature birth and low birth weight.
Cardiovascular Disease: Folate helps regulate homocysteine levels. High homocysteine is linked to increased risk of heart disease and stroke by damaging artery linings. Correcting folate deficiency can lower these levels.
Mental and Cognitive Issues: Low folate is associated with neuropsychiatric symptoms, including depression, confusion, and cognitive decline, particularly in older adults. Folate is involved in neurotransmitter production, which deficiency disrupts.
Increased Cancer Risk: Some research suggests a link between low folate and increased risk of certain cancers, such as colorectal cancer, potentially due to folate's role in DNA stability. This area of research is complex and ongoing.

Comparing Folate and Vitamin B12 Deficiencies

Folate and Vitamin B12 deficiencies can share similar symptoms, especially megaloblastic anemia. Distinguishing between them is vital, as treating B12 deficiency solely with folate can mask the anemia while allowing neurological damage to worsen.


Feature	Folate Deficiency	Vitamin B12 Deficiency
Primary Cause	Poor diet, malabsorption, increased needs (pregnancy), alcohol use.	Often pernicious anemia, vegan diets, or poor absorption.
Onset of Symptoms	Can develop relatively quickly (months) due to limited body stores.	Develops slowly (years) due to larger body stores.
Hematologic Signs	Megaloblastic anemia.	Megaloblastic anemia, often with neurological damage.
Neurological Impact	Confusion, memory problems, depression; generally reversible.	Can cause irreversible neurological damage like peripheral neuropathy.
Oral Manifestations	Sore, red tongue; mouth ulcers.	Similar oral symptoms, but neurological issues differ.

Diagnosis and Treatment

Diagnosis involves blood tests for folate and B12 levels to check for deficiency or a dual deficiency. Treatment typically includes:

Dietary Adjustments: Increasing consumption of folate-rich foods like leafy greens, legumes, and citrus fruits. Cooking methods that preserve folate are important.
Folic Acid Supplements: Supplements are often recommended to quickly restore levels, particularly for women of childbearing age.
Addressing Underlying Causes: Treating conditions like celiac disease or alcoholism is necessary if they are the root cause.

Conclusion

Low folate levels can lead to various negative health outcomes, from fatigue to severe neurological issues and birth defects. Maintaining adequate folate intake is crucial for health due to its role in cell division and DNA synthesis. If you experience symptoms like persistent fatigue, a sore tongue, or mood changes, consult a healthcare provider. With diagnosis and treatment, often involving diet changes and supplements, the effects of low folate can be reversed, and the risk of complications reduced. For more information, visit the National Institutes of Health (NIH) website.

Note: This article is for informational purposes only and does not constitute medical advice. Consult a healthcare professional for diagnosis and treatment.

Frequently Asked Questions

Because the body only stores a small amount of folate, a deficiency can develop within a few months if intake is inadequate.

Yes, low folate is a common cause of megaloblastic anemia, a condition where the red blood cells are abnormally large and fewer in number, leading to fatigue and weakness.

Neurological side effects can include headaches, irritability, difficulty concentrating, confusion, memory problems, depression, and, in severe cases, dementia or peripheral neuropathy.

Yes, folate deficiency during early pregnancy significantly increases the risk of the baby developing severe birth defects of the brain and spinal cord, known as neural tube defects.

Treatment involves increasing dietary intake of folate-rich foods and taking folic acid supplements, as recommended by a healthcare provider.

Folate is the naturally occurring form of vitamin B9 found in foods, while folic acid is the synthetic form used in supplements and fortified foods.

Yes, folate is necessary for metabolizing the amino acid homocysteine. Low folate can lead to elevated homocysteine levels, which are associated with an increased risk of cardiovascular disease and stroke.