What Does It Mean When Your Folate Is Too High?

December 24, 2025 •

2 min read

According to the National Institutes of Health, a folate level greater than 20 ng/mL on a blood test is typically considered elevated. While often resulting from excessive folic acid from supplements or fortified foods, high folate can signify underlying health issues or mask a serious vitamin B12 deficiency.

Quick Summary

Elevated folate levels, also known as hyperfolatemia, often stem from overconsumption of folic acid supplements or fortified foods. This condition can mask an underlying vitamin B12 deficiency, potentially leading to neurological damage if left unaddressed. It may also result from certain genetic factors or medical conditions, and is associated with various health concerns.

Key Points

High Folate Often Signals High Folic Acid: Elevated folate levels are typically caused by overconsumption of synthetic folic acid from supplements and fortified foods, not from natural food folate.
Masks a Dangerous B12 Deficiency: A primary risk of high folate is its ability to correct the anemia of a vitamin B12 deficiency while allowing neurological damage to progress undetected.
Neurological and Cognitive Risks: Excessive folic acid has been linked to cognitive impairment, especially in older adults with low B12, and can worsen existing neurological symptoms.
Potential Cancer and Immune Concerns: Some research suggests a link between high folic acid and increased cancer risk or altered immune function, particularly involving natural killer cells.
Requires Medical Review: If you have high folate, it is critical to consult a doctor to test for vitamin B12 deficiency and review all sources of supplemental and fortified folic acid.
Adjust Supplementation, Consider Methylfolate: Management often involves reducing or stopping excessive folic acid supplements and, for some, switching to the active form, methylfolate.

Understanding Elevated Folate and Its Implications

Folate (vitamin B9) is essential for numerous bodily functions, including cell growth, DNA synthesis, and red blood cell formation. The natural form found in foods is folate, while the synthetic form in fortified foods and supplements is folic acid. While important, particularly during pregnancy, excessive levels can lead to complications.

Common Causes of High Folate Levels

High folate is often due to synthetic folic acid intake. Key causes include excessive supplementation, consumption of fortified foods, vitamin B12 deficiency, genetic factors like MTHFR variations, and certain medical conditions.

Health Risks Associated with Excess Folate

The primary risk is a masked B12 deficiency, but others include cognitive decline, potential immune system modulation, and possible cancer risks.

Natural Folate vs. Synthetic Folic Acid: A Comparison

Natural folate and synthetic folic acid differ in metabolism and implications:


Feature	Natural Food Folate	Synthetic Folic Acid
Source	Foods like leafy greens, legumes, citrus fruits.	Supplements and fortified foods.
Metabolism	Easily metabolized to active 5-MTHF.	Requires enzyme (MTHFR); high doses can overwhelm.
Toxicity	Not toxic from food.	High intake can lead to unmetabolized folic acid.
Regulatory Risk	No masking of B12 deficiency.	Can mask B12 deficiency symptoms.
Supplementation Risk	Low overconsumption risk from food.	High risk from supplements and fortified foods.

How to Address High Folate Levels

If folate levels are high, consult a healthcare provider to find the cause, especially checking for B12 deficiency.

Steps to lower elevated folate levels:

Reduce Folic Acid Intake: Review and potentially reduce supplements and fortified foods under medical guidance.
Test Vitamin B12 Levels: Crucially test for B12 deficiency before making major changes.
Consider Methylfolate: For some, including those with MTHFR variations, switching to active methylfolate (5-MTHF) may be beneficial as it doesn't accumulate like unmetabolized folic acid.
Manage Underlying Conditions: Address conditions like liver or kidney disease if they contribute to high folate.
Recheck Levels: Follow up with your doctor to retest folate and B12 levels; high folate usually normalizes weeks after reducing intake.

Conclusion: Navigating Folate Balance with Caution

Elevated folate is not always benign and can signal a serious, masked vitamin B12 deficiency. Due to food fortification and supplement use, excessive synthetic folic acid intake is common. By understanding the difference between natural and synthetic forms, monitoring intake, and working with a doctor, you can maintain healthy B vitamin levels and avoid risks from excess folate.

Frequently Asked Questions

The primary danger is that high folate levels can correct the megaloblastic anemia caused by a vitamin B12 deficiency, but they do not prevent the progressive and potentially irreversible neurological damage that accompanies it.

No, it is highly unlikely to get dangerously high levels of folate from naturally occurring food sources alone. The risks associated with excess folate primarily come from overconsumption of synthetic folic acid from supplements and fortified foods.

High folate levels may not cause noticeable symptoms, but some people experience digestive upset, irritability, sleep problems, or difficulty concentrating. If a B12 deficiency is also present, neurological symptoms like numbness or tingling may occur.

To lower your levels, you should first consult a doctor. Management typically involves reducing or stopping excessive folic acid supplements, moderating your intake of fortified foods, and getting tested for a vitamin B12 deficiency.

UMFA is synthetic folic acid that the body has not fully converted into its active form because the metabolic pathway is saturated or inefficient. A buildup of UMFA in the blood has been linked to health concerns like altered immune responses.

For individuals with high folate levels or certain genetic variations (like MTHFR), switching to the active form, methylfolate, may be beneficial. Methylfolate does not accumulate in the same way as unmetabolized folic acid and is more readily utilized by the body.

The Tolerable Upper Intake Level for folic acid from supplements and fortified foods is 1,000 micrograms (1 mg) per day for adults. This limit is to avoid masking a vitamin B12 deficiency.