What happens to your body if you lack folic acid?

November 13, 2025 •

3 min read

The human body stores only a small amount of folate, meaning a deficiency can develop within just a few months if dietary intake is insufficient. This can cause a range of symptoms and serious complications, revealing precisely what happens to your body if you lack folic acid. The consequences extend beyond simple tiredness to affect nearly every system.

Quick Summary

Folic acid deficiency impairs DNA and red blood cell production, leading to megaloblastic anemia, fatigue, and weakness. It can also cause birth defects and affect neurological and mental health. Severe cases impact multiple body systems.

Key Points

Megaloblastic Anemia: A lack of folic acid impairs red blood cell production, leading to oversized, improperly functioning cells that cause fatigue, weakness, and paleness.
Neurological & Psychological Symptoms: Deficient folate levels can result in irritability, confusion, depression, memory issues, and reduced cognitive function.
Risks for Fetal Development: During pregnancy, a severe deficiency can cause neural tube defects like spina bifida and anencephaly, as well as preterm birth.
Gastrointestinal Distress: Low folate can lead to a sore, red tongue, mouth sores, and digestive issues like diarrhea.
Cardiovascular and Cancer Risks: Chronic deficiency can increase homocysteine levels, raising the risk of cardiovascular disease and certain cancers, particularly colon cancer.
Rapid Onset of Deficiency: Due to the body's small folate stores, dietary deficiency can develop within just a few months.
Diagnosis is Distinct from B12: While deficiencies can cause similar anemia, neurological symptoms often differ, and distinguishing between them via blood tests (including MMA levels) is critical for proper treatment.

The Fundamental Role of Folic Acid

Folic acid, or vitamin B9, is a water-soluble vitamin essential for a multitude of bodily processes. Its primary function lies in the synthesis of DNA and RNA, which are the blueprints for every cell in your body. This vital role means that any shortage directly impacts rapidly dividing cells, such as those that form red blood cells, tissues during growth, and those in the developing fetus. Without enough folic acid, the body cannot produce these cells properly, leading to systemic dysfunction.

Hematological Effects: Folate Deficiency Anemia

One of the most immediate and widespread consequences of insufficient folic acid is megaloblastic anemia. This condition occurs when the body produces abnormally large, immature, and misshapen red blood cells that cannot function effectively. These cells are less capable of carrying oxygen, depriving the body's tissues and organs of the oxygen they need to perform their jobs.

Symptoms of Megaloblastic Anemia

Extreme fatigue and lack of energy
General weakness
Pale skin
Shortness of breath, even during light activity
Dizziness
Irregular or rapid heartbeats (palpitations)
Headaches

Neurological and Psychiatric Consequences

Folic acid also plays a critical role in nervous system function and mental well-being. A deficiency can lead to a variety of neurological and psychiatric symptoms, though some of the more severe nerve damage symptoms are often more indicative of a coexisting Vitamin B12 deficiency.

Neurological and Mental Health Symptoms

Irritability and confusion
Depression
Memory loss and difficulty concentrating
Pins and needles (paraesthesia) in the hands and feet
Changes in behavior and judgment

Risks During Pregnancy and Fetal Development

Folic acid is crucially important for women who are pregnant or planning to become pregnant. The period of fetal development involves extremely rapid cell division, and a folic acid deficiency during this time can lead to serious birth abnormalities, including neural tube defects (NTDs).

Complications During Pregnancy

Neural Tube Defects: The most well-known risk, including spina bifida and anencephaly, which affect the brain and spinal cord.
Increased Homocysteine Levels: Elevated levels can increase the risk of vascular issues.
Premature Birth and Low Birth Weight: A lack of folate is associated with higher rates of preterm birth and low infant birth weight.

Comparison of Deficiencies: Folic Acid vs. Vitamin B12

While folic acid and vitamin B12 deficiencies share some overlapping symptoms, particularly megaloblastic anemia, they are distinct conditions. It is crucial to test for and diagnose both, as treating a vitamin B12 deficiency with only folic acid can mask the anemia while allowing neurological damage to progress.


Feature	Folic Acid Deficiency	Vitamin B12 Deficiency
Primary Function	DNA/RNA synthesis, red blood cell maturation	DNA/RNA synthesis, nervous system health
Neurological Symptoms	Present, but often less severe; include confusion, depression	Can be more severe and permanent if untreated; includes tingling, numbness, balance issues
Homocysteine Level	Elevated	Elevated
Methylmalonic Acid (MMA) Level	Normal	Elevated
Primary Dietary Source	Leafy greens, legumes, fortified grains	Meat, eggs, dairy products

Causes and Diagnosis

Aside from a poor diet lacking in leafy greens, citrus fruits, and fortified grains, several other factors can lead to folic acid deficiency. Malabsorption issues, such as those associated with Crohn's or Celiac disease, certain medications (like methotrexate), and excessive alcohol consumption are common culprits. Pregnant individuals and those with chronic hemolytic anemia also have an increased need for folate. A diagnosis is typically made with a blood test that measures serum folate levels, along with a complete blood count (CBC) to check for megaloblastic anemia.

Treatment and Prevention

Treatment for folic acid deficiency typically involves supplementation and dietary changes to increase folate intake. The effects of addressing the deficiency are often seen quickly, with anemia resolving in a matter of weeks. Pregnant individuals or those trying to conceive are often advised to take a supplement as a preventative measure, as are other at-risk groups. Mandatory fortification of grains in some countries has significantly reduced the prevalence of deficiency. For more in-depth medical information on diagnosis and treatment, consult the StatPearls resource on Folic Acid Deficiency.

Conclusion: Prioritizing Folic Acid Intake

Understanding what happens to your body if you lack folic acid highlights its profound importance for overall health, from red blood cell production to brain function and fetal development. The symptoms, ranging from simple fatigue to complex neuropsychiatric issues and serious birth defects, underscore the need for adequate intake. Fortunately, this deficiency is highly treatable through supplementation and diet, making prevention and early intervention key to avoiding its wide-ranging and serious complications.

Frequently Asked Questions

The most common early sign of folic acid deficiency is megaloblastic anemia, which causes extreme fatigue, weakness, and paleness due to the body's inability to produce enough healthy red blood cells.

Because the body only stores a small amount of folate, a deficiency can develop and cause symptoms to appear within a few months of low intake. For comparison, a Vitamin B12 deficiency may take years to manifest.

Yes, it can. While overt neurological deficits are less common than in Vitamin B12 deficiency, neuropsychiatric symptoms like depression, irritability, and cognitive decline can occur.

While natural folate is found in many foods like leafy greens, citrus fruits, and legumes, folic acid from fortified foods and supplements is more easily absorbed by the body. For at-risk groups like pregnant women, supplementation is highly recommended.

Yes. A folic acid deficiency can lead to elevated levels of homocysteine, an amino acid associated with an increased risk of cardiovascular disease, including stroke.

Folate is the naturally occurring form of vitamin B9 found in food, while folic acid is the synthetic, man-made form found in fortified foods and supplements. Folic acid is more easily absorbed by the body.

A doctor can diagnose a folic acid deficiency with a blood test to check the serum folate levels. They will also typically order a complete blood count to check for megaloblastic anemia and may test Vitamin B12 levels to rule out a dual deficiency.