Why am I not absorbing folate? A guide to causes and treatment

January 7, 2026 •

5 min read

According to research, up to 80% of chronic alcoholics have low serum folate levels due to impaired absorption and metabolism. If you consume enough folate but still show signs of deficiency, understanding the root cause is essential for your long-term health. This guide explores the reasons you might not be absorbing folate properly.

Quick Summary

Folate malabsorption can be caused by genetic variations like the MTHFR mutation, underlying medical conditions such as celiac and Crohn's disease, or certain medications. Lifestyle factors like chronic alcohol use also interfere with absorption. A medical diagnosis can help pinpoint the cause and determine the right treatment plan.

Key Points

Genetic Mutations: Variants in the MTHFR gene can impair the body's ability to convert folate into its active, usable form, 5-methyl-THF.
Digestive Issues: Conditions like celiac disease, Crohn's disease, and bariatric surgery damage the small intestine, directly preventing efficient folate absorption.
Medication Interference: Certain drugs, including methotrexate and some anti-seizure medications, can actively block folate metabolism or reduce its absorption.
Chronic Alcohol Use: Excessive alcohol consumption irritates the gut lining and increases urinary excretion, leading to a significant depletion of folate over time.
Hidden B12 Deficiency: An underlying vitamin B12 deficiency can trap folate in an inactive form, preventing its proper function within the body, making proper diagnosis crucial.
Proper Diagnosis is Key: The path to resolving folate malabsorption depends entirely on identifying the correct root cause, which requires a medical evaluation and blood tests.

The Importance of Folate and the Absorption Process

Folate, or vitamin B9, is a crucial water-soluble vitamin necessary for numerous bodily functions. It plays a vital role in the synthesis of DNA and RNA, cell growth, red blood cell formation, and methylation, a critical process for regulating genes and detoxifying the body. When you consume dietary folate, it is absorbed primarily in the jejunum, a part of the small intestine, by a protein transporter called the proton-coupled folate transporter (PCFT). However, several factors can disrupt this process, preventing your body from getting the folate it needs. Understanding these issues is the first step toward finding a solution.

Genetic Factors Affecting Folate Absorption

For some individuals, the inability to absorb or utilize folate is rooted in their genetics. The most commonly discussed genetic variant is related to the MTHFR gene.

MTHFR Gene Mutation

The methylenetetrahydrofolate reductase (MTHFR) enzyme is responsible for converting folate into its active form, 5-methyl-THF. A mutation in the MTHFR gene, particularly the C677T variant, can reduce the enzyme's efficiency.

Enzyme inefficiency: Individuals with this mutation have a reduced ability to convert synthetic folic acid into its usable form. While they can still process folate, their bodies may struggle to keep up, especially under stress or with poor dietary habits.
Elevated homocysteine: The inefficient conversion process can lead to a buildup of homocysteine, an amino acid linked to cardiovascular issues when elevated.
Solution: For those with MTHFR mutations, supplementation with the active form of folate, L-methylfolate, is often recommended instead of standard folic acid.

Hereditary Folate Malabsorption

This is a very rare genetic disorder caused by mutations in the SLC46A1 gene, which encodes the PCFT transporter. Without a functional PCFT, the body cannot absorb folate efficiently from the intestines or transport it into the central nervous system.

Severe deficiency: This inherited condition can cause severe systemic and neurological issues from infancy.
Intramuscular treatment: Since oral absorption is severely compromised, treatment often involves high doses of intramuscular folinic acid to bypass the intestinal transport issue.

Medical Conditions That Impair Absorption

Digestive disorders and other health issues can significantly impact the small intestine's ability to absorb folate, regardless of dietary intake.

Digestive System Disorders

Celiac Disease: An autoimmune disorder where consuming gluten damages the small intestine lining, specifically the villi responsible for nutrient absorption. This widespread damage leads to generalized malabsorption, including folate.
Crohn's Disease: A type of inflammatory bowel disease that causes inflammation of the lining of the digestive tract. The chronic inflammation can reduce the efficiency of the small intestine in absorbing nutrients.
Bariatric Surgery: Procedures like gastric bypass can alter the digestive system and reduce the area available for nutrient absorption, increasing the risk of folate deficiency.

Other Health Conditions

Chronic Alcohol Use: Excessive alcohol consumption irritates the intestinal lining, impairs folate transport, and interferes with the liver's metabolism of folate. It also increases urinary folate excretion.
Vitamin B12 Deficiency: Folate and vitamin B12 work together. A B12 deficiency can lead to a 'folate trap,' where folate is unusable, causing a functional folate deficiency even if levels appear normal. Diagnosis requires testing for both vitamins.
Kidney Dialysis: Patients undergoing long-term kidney dialysis may lose folate from the body due to the frequent urination and dialysis process.

Medications That Interfere with Folate

Certain pharmaceutical drugs can interfere with folate absorption and metabolism, leading to a deficiency over time.

Methotrexate: Used to treat certain cancers and autoimmune diseases, methotrexate is a folate antagonist that blocks the enzyme dihydrofolate reductase, inhibiting folate utilization.
Anti-seizure drugs: Medications such as phenytoin and carbamazepine can cause a folate deficiency by impairing absorption or affecting metabolism.
Sulfasalazine: Prescribed for inflammatory bowel disease and rheumatoid arthritis, this medication can reduce the body's ability to absorb folate.
Proton Pump Inhibitors (PPIs): While evidence is mixed, some studies suggest that these acid-reducing medications could interfere with absorption, particularly of B12, which works closely with folate.

Comparison of Common Folate Deficiency Causes

To understand the difference between common causes, see the table below:


Cause	Mechanism of Action	Common Symptoms	Associated Factors
Dietary Insufficiency	Inadequate intake of folate-rich foods or overcooking	Fatigue, weakness, mouth sores	Poor diet, alcoholism, fad diets
MTHFR Gene Mutation	Reduced enzyme efficiency to convert folate to its active form	Elevated homocysteine, mental health issues	Genetic predisposition, often requires methylated folate
Celiac/Crohn's Disease	Damage or inflammation to the intestinal lining	Diarrhea, weight loss, abdominal pain, anemia	Autoimmune disease, gluten sensitivity
Chronic Alcohol Use	Interferes with absorption and increases excretion	Fatigue, anemia, neurological symptoms	High alcohol intake, malnutrition
Certain Medications	Antagonist action or impaired absorption	Depends on the medication and severity	Prescription drug use for specific conditions

Dietary Strategies and Proper Supplementation

If you have ruled out or addressed underlying medical causes with a healthcare provider, optimizing your diet and supplementation strategy is crucial.

Consume Folate-Rich Foods: Incorporate a variety of dark green leafy vegetables, legumes, citrus fruits, and fortified grains into your diet.
Proper Cooking Methods: Since folate is sensitive to heat, using cooking methods like steaming or stir-frying can help preserve the nutrient content.
Consider Active Folate: If a genetic issue like an MTHFR mutation is the cause, discuss taking L-methylfolate supplements with your doctor, as this form is more readily utilized by the body.
Address Vitamin B12 Levels: Always have your vitamin B12 levels checked before beginning high-dose folate supplementation, as it can mask an underlying B12 deficiency.

Conclusion

The question of 'Why am I not absorbing folate?' has multiple potential answers, ranging from common dietary habits to complex genetic and medical issues. Rather than self-diagnosing, the best approach is to consult a healthcare professional. Through a blood test and medical history review, they can help identify the root cause and recommend an effective treatment plan, whether it involves simple dietary changes, a different form of supplementation, or addressing an underlying condition. Taking proactive steps to resolve folate malabsorption is key to preventing long-term health complications like anemia and elevated homocysteine levels.

For more detailed information on folate deficiency, consult reputable medical resources like the Cleveland Clinic.

Frequently Asked Questions

Common symptoms include fatigue, weakness, pale skin, irritability, sore tongue, mouth ulcers, diarrhea, and a reduced sense of taste. Untreated deficiency can also lead to megaloblastic anemia.

Diagnosis typically involves a blood test to measure serum folate levels. Your doctor will also take a medical history to identify potential causes like diet, medication use, or underlying health conditions.

For individuals with an MTHFR mutation, supplementing with L-methylfolate is often recommended because it is the active form of folate and does not require the MTHFR enzyme for conversion.

Yes, chronic and excessive alcohol use is a major cause of folate deficiency. It disrupts absorption in the gut, impairs the liver's ability to metabolize folate, and increases excretion.

The 'folate trap' occurs when a vitamin B12 deficiency prevents the conversion of folate into its active form. This means folate gets trapped in an unusable state, and high-dose folate supplementation without addressing the B12 issue can mask the B12 deficiency's symptoms.

Yes, several medications can interfere with folate, including methotrexate, some anti-seizure drugs (like phenytoin), and sulfasalazine. If you take these medications, your doctor may monitor your folate levels.

The synthetic form of folate, folic acid, found in supplements and fortified foods, is often absorbed more easily by the body compared to natural food folate.

With appropriate treatment, which may include addressing the underlying cause and taking folic acid tablets, it usually takes about four months for folate levels to return to normal.

Yes, prolonged exposure to high heat, such as overcooking, can destroy the naturally occurring folate in fruits and vegetables. Cooking with gentler methods like steaming helps preserve more of the vitamin.