What does low folate feel like? Understanding the signs and symptoms

December 28, 2025 •

5 min read

According to the CDC, mandatory folic acid fortification in the United States has significantly reduced the prevalence of frank folate deficiency, yet certain populations remain at risk. A deficiency in this essential B vitamin (B9) can manifest as a wide array of physical and mental symptoms that can be easy to overlook, often developing gradually over time.

Quick Summary

Low folate often causes fatigue, weakness, irritability, and cognitive difficulties, which stem from reduced red blood cell production. It can also lead to oral symptoms like a sore tongue and mouth ulcers, as well as digestive issues, and is treatable with proper diet and supplementation.

Key Points

Persistent Fatigue and Weakness: One of the most common signs of low folate is extreme tiredness that does not improve with rest, a result of decreased red blood cell production.
Mouth Sores and Red Tongue: Folate deficiency can cause a smooth, sore, and red tongue (glossitis), as well as painful mouth ulcers.
Mood and Cognitive Changes: Low folate levels can impact mental health, leading to symptoms like irritability, depression, anxiety, and difficulty concentrating.
Important to Differentiate from B12: Folate and vitamin B12 deficiencies share many symptoms, but B12 deficiency can cause irreversible neurological damage, a key distinction for diagnosis and treatment.
Causes Beyond Diet: While diet is a factor, low folate can also be caused by alcohol abuse, malabsorption disorders, certain medications, and increased demand during pregnancy.
Treatable with Supplements: Treatment typically involves oral folic acid supplementation and dietary adjustments, which are highly effective in reversing symptoms.
Prevention is Key: Eating a balanced diet rich in leafy greens, legumes, and fortified grains is crucial for preventing a deficiency.

Folate is a critical B vitamin, also known as B9, that plays a vital role in the synthesis and repair of DNA, RNA, and proteins. When your body lacks sufficient folate, it can lead to a condition called folate deficiency, which, if severe, can cause megaloblastic anemia. This type of anemia is characterized by abnormally large, immature red blood cells that cannot function correctly, reducing oxygen delivery throughout the body. The effects of low folate can therefore be felt in nearly every bodily system.

The Primary Physical Symptoms of Low Folate

Many of the initial symptoms of a folate deficiency are tied to the reduced production of healthy red blood cells, which directly impacts the body's energy and oxygen supply.

General and Energy-Related Signs

Extreme tiredness and weakness: Persistent fatigue is one of the most common and earliest indicators of low folate. Unlike normal tiredness, this exhaustion often doesn't improve with rest.
Lack of energy (lassitude): A general feeling of low energy and a reduced ability to perform daily tasks can occur as the body's oxygen-carrying capacity decreases.
Pale skin (pallor): A visibly paler complexion, especially noticeable on the inner eyelids and nail beds, is a classic sign of anemia caused by reduced red blood cells.
Shortness of breath (dyspnea): During physical exertion, or even at rest in severe cases, the lack of sufficient oxygen can cause a feeling of breathlessness.
Dizziness and lightheadedness: The brain's reduced oxygen supply can lead to feelings of lightheadedness or dizziness, sometimes causing palpitations.
Headaches: Frequent or persistent headaches can result from inadequate oxygen reaching the brain.

Oral, Digestive, and Psychological Manifestations

Beyond the signs of anemia, low folate can produce other specific and noticeable symptoms, particularly affecting the mouth, gut, and brain function.

Oral and Digestive Issues

A smooth, sore, and red tongue (glossitis): The tongue may become tender, swollen, and appear unusually red due to cell changes.
Mouth ulcers: Painful sores or ulcers can develop in the mouth as a result of the deficiency.
Loss of appetite and weight loss: The combination of general fatigue and oral discomfort can lead to a reduced desire to eat, causing unintended weight loss.
Diarrhea: Some individuals may experience gastrointestinal distress, including diarrhea.

Mental and Neurological Effects

Irritability and mood changes: Folate is essential for the production of neurotransmitters like serotonin and dopamine, so low levels can disrupt mood regulation, leading to increased irritability, anxiety, or depression.
Difficulty concentrating ("brain fog"): Cognitive impairment, including forgetfulness and a reduced ability to focus, is a recognized symptom.
Confusion: In more severe cases, confusion and problems with judgment can occur, especially in older adults.

Folate vs. Vitamin B12 Deficiency: A Crucial Comparison

Folate and vitamin B12 work closely together in the body, and a deficiency in either can cause megaloblastic anemia. However, it's critical to differentiate between them, as their treatments and long-term consequences differ. Notably, vitamin B12 deficiency, if left untreated, can lead to irreversible nerve damage, a complication typically not seen in isolated folate deficiency.


Characteristic	Folate Deficiency	Vitamin B12 Deficiency
Primary Causes	Inadequate diet, malabsorption issues (celiac disease, Crohn's), alcoholism, certain medications, increased needs (pregnancy)	Poor absorption (pernicious anemia), vegan diet, atrophic gastritis
Anemia Type	Megaloblastic anemia (large, immature red blood cells)	Megaloblastic anemia
Neurological Symptoms	Mood changes, cognitive issues (reversible). No permanent nerve damage	Numbness, tingling, balance problems, memory loss, dementia (can be irreversible)
Homocysteine Levels	Elevated	Elevated
Methylmalonic Acid (MMA) Levels	Normal	Elevated
Treatment	Oral folic acid supplements	Vitamin B12 injections or high-dose oral supplements

Causes of Low Folate and Who is at Risk

While dietary insufficiency is a common cause, especially in areas without food fortification, other factors can also lead to low folate levels.

Risk Factors for Folate Deficiency

Poor diet: Not consuming enough folate-rich foods like leafy greens, citrus fruits, and legumes.
Alcohol abuse: Chronic alcohol consumption interferes with folate absorption and metabolism.
Malabsorptive disorders: Conditions like celiac disease, inflammatory bowel disease, and short bowel syndrome can hinder the absorption of nutrients.
Medications: Certain drugs, including some anti-seizure medications and those for ulcerative colitis, can interfere with folate.
Increased physiological demand: Pregnancy, breastfeeding, and rapid growth periods require higher folate intake. For example, the CDC recommends that all women who are planning or are capable of becoming pregnant take a daily folic acid supplement to prevent neural tube defects.
Kidney dialysis: This treatment can increase folate loss.
Genetic factors: A polymorphism in the MTHFR gene affects how some people convert folate to its active form.

Diagnosis and Treatment

If you suspect you have a folate deficiency based on your symptoms, a healthcare provider can confirm the diagnosis with a simple blood test. Treatment is straightforward and highly effective once the underlying cause is identified.

How Folate Deficiency is Treated

Folic acid supplements: Oral supplementation is the most common form of treatment. Your doctor will recommend the appropriate amount based on your individual needs.
Dietary changes: A registered dietitian can help you incorporate more folate-rich foods into your diet. Cooking methods that preserve folate, such as steaming rather than boiling, are also important.
Address underlying conditions: For malabsorption issues or medication interference, treating the primary condition or adjusting prescriptions is necessary.
Check B12 levels: It is vital to test for vitamin B12 deficiency simultaneously, as treating a B12 deficiency with folate alone can mask the anemia while allowing neurological damage to progress.

Conclusion

Low folate can manifest in a variety of ways, ranging from overwhelming fatigue and oral discomfort to significant mood and cognitive changes. While some symptoms overlap with other conditions, a proper diagnosis through a blood test is simple and can lead to effective treatment. Understanding the potential signs of low folate and recognizing your personal risk factors are the first steps toward addressing the issue. With proper supplementation and dietary adjustments, the effects of a folate deficiency are typically reversible, allowing you to recover your energy and well-being. If you are experiencing persistent or concerning symptoms, consult a healthcare professional for accurate diagnosis and guidance. You can learn more about the different forms of folate and folic acid from the National Institutes of Health.

Note: The information in this article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any treatment or supplementation.

Frequently Asked Questions

The earliest signs of low folate often include persistent fatigue, a feeling of weakness, and a general lack of energy. You may also notice pallor, or pale skin, as your red blood cell count decreases.

Yes, low folate can significantly impact your mental health. Folate is important for producing mood-regulating neurotransmitters like serotonin and dopamine, and a deficiency can lead to irritability, anxiety, and depressive symptoms.

No, while often used interchangeably, they are different. Folate is the naturally occurring form of vitamin B9 found in food, while folic acid is the synthetic, man-made version used in supplements and fortified foods.

Excellent food sources of folate include dark leafy greens like spinach, broccoli, and Brussels sprouts. Legumes (beans, peas, and lentils), citrus fruits, and fortified breakfast cereals are also good sources.

A folate deficiency is diagnosed through a blood test ordered by a healthcare provider. The test measures the amount of folate in your blood, and sometimes also measures red blood cell folate for a longer-term assessment.

The primary treatment for low folate is taking daily folic acid supplements, as prescribed by your doctor. It is also important to increase your intake of folate-rich foods and address any underlying causes, such as malabsorption issues.

While both can cause megaloblastic anemia and fatigue, a key difference lies in their neurological effects. Vitamin B12 deficiency can lead to irreversible nerve damage, numbness, and balance problems, which are not typical of an isolated folate deficiency.

Certain groups are at a higher risk, including pregnant women, people who abuse alcohol, individuals with malabsorptive disorders like celiac disease, and those on certain medications. Increased demand or poor absorption are common culprits.