What causes high folate levels?
High folate levels can result from excessive supplementation, fortified foods, certain medications, or underlying conditions like kidney disease or vitamin B12 deficiency. While folate is essential for health, elevated levels may mask B12 deficiency and require medical evaluation.
Understanding Folate and Its Role in Your Body
Folate, also known as vitamin B9, is a water-soluble vitamin that plays a crucial role in DNA synthesis, red blood cell formation, and proper cell division. Your body uses folate to create new cells, support brain function, and maintain cardiovascular health. During pregnancy, adequate folate levels are especially critical for preventing neural tube defects in developing babies.
While folate deficiency has been a historical concern leading to widespread food fortification programs, the modern diet and supplement use have created a new consideration: elevated folate levels. Understanding what causes high folate levels and their potential implications is important for optimizing your health and ensuring proper nutrient balance.
Normal vs. High Folate Levels: What the Numbers Mean
Normal serum folate levels typically range from 2.7 to 17.0 nanograms per milliliter (ng/mL), though reference ranges can vary slightly between laboratories. Levels above 20 ng/mL are generally considered elevated, and levels exceeding 24 ng/mL are definitively high. Red blood cell folate, which provides a longer-term view of folate status, normally ranges from 140 to 628 ng/mL.
Folate Level Categories and Clinical Implications
| Folate Level (ng/mL) | Category | Potential Causes | Health Considerations | |
|---|---|---|---|---|
| Below 2.7 | <2.7 ng/mL | Deficient | Poor diet, malabsorption, medications | Risk of anemia, neural tube defects, elevated homocysteine |
| 2.7-17.0 | 2.7-17.0 ng/mL | Normal | Balanced diet and supplementation | Optimal for most individuals |
| 17.1-20.0 | 17.1-20.0 ng/mL | High-Normal | Supplementation, fortified foods | Monitor for B12 status |
| 20.1-24.0 | 20.1-24.0 ng/mL | Elevated | Excess supplementation, kidney issues | May mask B12 deficiency, review intake |
| Above 24.0 | >24.0 ng/mL | High | Multiple supplements, kidney disease, medications | Requires evaluation, check B12, reduce supplementation |
Folate levels should always be interpreted alongside vitamin B12 levels and clinical symptoms for accurate assessment.
It's important to note that folate exists in two main forms: naturally occurring folate found in foods and synthetic folic acid used in supplements and fortified foods. Your body processes these forms differently, with synthetic folic acid potentially accumulating more readily when consumed in large amounts. Regular monitoring through comprehensive blood testing can help you understand your folate status and its relationship to other B vitamins.
Primary Causes of Elevated Folate Levels
Excessive Supplementation
The most common cause of high folate levels is taking too many supplements containing folic acid. Many people take multiple supplements without realizing they're getting folic acid from several sources. For example, you might be taking a multivitamin, a B-complex supplement, and a prenatal vitamin, each containing folic acid. The recommended daily allowance for adults is 400 micrograms (mcg), but some supplements contain 800-1000 mcg or more per serving.
High-dose folic acid supplements (5 mg or 5000 mcg) prescribed for certain medical conditions can significantly elevate blood levels. While these doses may be necessary for specific situations, they should only be taken under medical supervision to avoid potential complications from excessive intake.
Fortified Foods and Dietary Sources
In many countries, including the United States, grain products are fortified with folic acid to prevent deficiency. Enriched breads, cereals, pasta, and rice can contribute substantial amounts of folic acid to your daily intake. When combined with a diet rich in natural folate sources like leafy greens, legumes, and citrus fruits, plus supplementation, total intake can exceed recommended levels.
Some energy drinks, protein bars, and meal replacement products also contain added folic acid. Reading nutrition labels carefully can help you track your total folate intake from all sources and avoid unintentional overconsumption.
Medical Conditions Associated with High Folate
Kidney Disease and Impaired Clearance
Your kidneys play a vital role in filtering excess water-soluble vitamins, including folate, from your blood. When kidney function is compromised, folate clearance decreases, potentially leading to accumulation. Chronic kidney disease, acute kidney injury, or even mild reductions in kidney function can affect folate levels. This is why regular monitoring of kidney function markers like creatinine and eGFR is important when evaluating elevated folate levels.
Vitamin B12 Deficiency and Folate Trap
A particularly concerning scenario involves the relationship between folate and vitamin B12. When B12 levels are low, folate can become "trapped" in a form that the body cannot use effectively, leading to elevated serum folate levels. This condition, known as the methyl-folate trap, can mask B12 deficiency symptoms while allowing neurological damage to progress. This is why testing both folate and B12 levels together is crucial for accurate assessment.
The masking effect is particularly dangerous because high folate can correct the anemia associated with B12 deficiency without addressing the neurological complications. This can lead to irreversible nerve damage if B12 deficiency goes undiagnosed and untreated.
Upload your blood test results to track your progress
Seamlessly upload 3rd party biomarker & blood tests to track your whole health in 1 dashboard. Understand what each blood test means and how it fits into the bigger picture of your body and health.
Get diet and lifestyle recommendations based on your blood results, health profile and health goals. You'll also receive a custom supplement recommendation for the precise nutrients your body craves.
Upload Past Blood Test Results
Click or drag file to upload
Once you upload your report, we'll extract the results for your review. Works with top labs including Quest Diagnostics, LabCorp, BioReference, EverlyWell, LetsGetChecked and hundreds of other labs.
Medications That Can Increase Folate Levels
Several medications can interfere with folate metabolism or excretion, leading to elevated levels. Certain antibiotics, particularly sulfonamides and trimethoprim, can affect folate processing. Some anti-seizure medications paradoxically can cause both low and high folate levels depending on individual metabolism and dosing.
Methotrexate, used for rheumatoid arthritis and certain cancers, is often prescribed alongside high-dose folic acid to reduce side effects. This therapeutic use can result in significantly elevated folate levels. If you're taking any medications regularly, discussing their potential impact on folate levels with your healthcare provider is important.
Symptoms and Health Implications of High Folate
While folate toxicity is rare due to its water-soluble nature, consistently high levels can cause various symptoms and health concerns. Some people experience digestive issues like nausea, bloating, or loss of appetite. Neurological symptoms may include difficulty concentrating, irritability, or sleep disturbances. In some cases, high folate levels have been associated with an increased risk of certain cancers, though research is ongoing.
The most significant concern with high folate is its potential to mask vitamin B12 deficiency. This can delay diagnosis and treatment, allowing B12 deficiency to cause permanent neurological damage. Symptoms of masked B12 deficiency include numbness and tingling in extremities, balance problems, memory issues, and mood changes. Understanding these risks underscores the importance of comprehensive testing that includes both folate and B12 levels.
Testing and Monitoring Your Folate Levels
Accurate assessment of folate status requires more than just a single folate test. A comprehensive approach includes serum folate, red blood cell folate, vitamin B12, and potentially homocysteine levels. Homocysteine can be elevated when either folate or B12 is functionally deficient, providing additional insight into your B-vitamin status.
Regular monitoring is particularly important if you take supplements, have kidney disease, follow a vegan diet, or take medications that affect folate metabolism. Testing every 3-6 months can help you track changes and adjust supplementation as needed. Home testing options now make it convenient to monitor these important biomarkers without frequent clinic visits.
Managing and Preventing Excessive Folate Levels
If testing reveals high folate levels, the first step is usually to review all sources of folic acid intake. This includes cataloging all supplements, fortified foods, and medications. Many people are surprised to discover they're getting folic acid from multiple sources. Reducing or eliminating supplementation often brings levels back to normal within a few weeks, as excess folate is excreted through urine.
- Inventory all supplements and check folic acid content
- Choose supplements without folic acid if levels are high
- Limit consumption of heavily fortified processed foods
- Focus on natural folate from whole foods rather than synthetic folic acid
- Ensure adequate B12 intake to prevent functional folate deficiency
- Work with a healthcare provider to adjust medications if necessary
For those who need folate supplementation due to pregnancy, certain medications, or medical conditions, using the active form (5-methyltetrahydrofolate or 5-MTHF) rather than synthetic folic acid may be beneficial. This form doesn't accumulate as readily and doesn't mask B12 deficiency to the same extent.
The Importance of Balanced B-Vitamin Status
Folate doesn't work in isolation - it's part of an intricate network of B vitamins that support methylation, energy production, and numerous other cellular processes. Optimal health requires balance among all B vitamins, not just adequate levels of individual nutrients. This interconnectedness is why comprehensive testing that includes multiple B vitamins provides a more complete picture of your nutritional status.
Understanding what causes high folate levels empowers you to make informed decisions about supplementation and diet. While folate is essential for health, more isn't always better. Regular monitoring, careful attention to total intake from all sources, and maintaining balance with other B vitamins, particularly B12, helps ensure optimal folate status without the risks associated with excess. By taking a thoughtful approach to folate intake and testing, you can support your body's methylation processes while avoiding the potential pitfalls of elevated levels.
References
- Bailey, L. B., Stover, P. J., McNulty, H., Fenech, M. F., Gregory, J. F., Mills, J. L., Pfeiffer, C. M., Fazili, Z., Zhang, M., Ueland, P. M., Molloy, A. M., Caudill, M. A., Shane, B., Berry, R. J., Bailey, R. L., Hausman, D. B., Raghavan, R., & Raiten, D. J. (2015). Biomarkers of Nutrition for Development-Folate Review. The Journal of Nutrition, 145(7), 1636S-1680S.[Link][PubMed][DOI]
- Morris, M. S., Jacques, P. F., Rosenberg, I. H., & Selhub, J. (2007). Folate and vitamin B-12 status in relation to anemia, macrocytosis, and cognitive impairment in older Americans in the age of folic acid fortification. The American Journal of Clinical Nutrition, 85(1), 193-200.[Link][PubMed][DOI]
- Selhub, J., & Paul, L. (2011). Folic acid fortification: why not vitamin B12 also? BioFactors, 37(4), 269-271.[PubMed][DOI]
- Field, M. S., & Stover, P. J. (2018). Safety of folic acid. Annals of the New York Academy of Sciences, 1414(1), 59-71.[Link][PubMed][DOI]
- Pfeiffer, C. M., Sternberg, M. R., Fazili, Z., Lacher, D. A., Zhang, M., Johnson, C. L., Hamner, H. C., Bailey, R. L., Rader, J. I., Yamini, S., Berry, R. J., & Yetley, E. A. (2015). Folate status and concentrations of serum folate forms in the US population: National Health and Nutrition Examination Survey 2011-2. British Journal of Nutrition, 113(12), 1965-1977.[PubMed][DOI]
- Obeid, R., Herrmann, W. (2012). The emerging role of unmetabolized folic acid in human diseases: myth or reality? Current Drug Metabolism, 13(8), 1184-1195.[PubMed][DOI]
Was this article helpful?
Frequently Asked Questions
How can I test my folate levels at home?
What is the normal range for folate levels?
Can high folate levels be dangerous?
How long does it take for folate levels to normalize after stopping supplements?
Should I stop taking folic acid if my levels are high?
This article is licensed under CC BY 4.0. You are free to share and adapt this material with attribution.
