Are B9 and methylfolate the same? The difference explained

November 29, 2025 •

4 min read

While often used interchangeably, natural folate found in food is less bioavailable than its active counterpart. The key difference lies in the forms of this essential nutrient, so are B9 and methylfolate the same? Not quite, and understanding the distinction is vital for proper absorption and overall health.

Quick Summary

Vitamin B9 is a blanket term for several compounds, including natural folate and synthetic folic acid, while methylfolate is the active, usable form of B9.

Key Points

Vitamin B9 is a family of compounds: B9 is the umbrella term for folate, folic acid, and methylfolate, which are all distinct forms of the same essential nutrient.
Methylfolate is the 'active' form: The body must convert folate (from food) and folic acid (synthetic) into methylfolate to be used effectively, especially for neurological functions.
MTHFR gene affects conversion: A common genetic variation can impede the body's ability to convert folic acid, making methylfolate supplements a better option for some people.
Supports vital processes: Methylfolate is crucial for healthy DNA synthesis, cell division, and the production of mood-regulating neurotransmitters like serotonin and dopamine.
Active form for better bioavailability: Unlike folic acid, methylfolate bypasses the conversion process, offering superior and immediate bioavailability for individuals with impaired folate metabolism.
Mindful of B12: High doses of synthetic folic acid can mask a vitamin B12 deficiency, potentially leading to nerve damage; it is safer to take a B complex or have your B12 levels checked.

What is Vitamin B9?

Vitamin B9 is a water-soluble vitamin essential for numerous bodily functions, including DNA synthesis, cell growth, and the production of healthy red blood cells. Without sufficient B9, your body cannot perform these critical processes correctly. However, Vitamin B9 is not a single chemical compound but a family of related compounds, and how it is labeled depends on its source and form. The three most common forms are natural folate, synthetic folic acid, and active methylfolate. This is the root of the confusion when asking, "Are B9 and methylfolate the same?" The answer is that methylfolate is a specific, active type of Vitamin B9, but not all B9 is methylfolate.

The Different Forms of Vitamin B9

Folate (Natural B9)

Folate refers to the forms of B9 that occur naturally in foods, particularly leafy greens, legumes, and eggs. To be utilized by the body, this dietary folate must be converted through several enzymatic steps in the intestines and liver to its active form, methylfolate. Unfortunately, natural folates are not particularly stable and can be easily destroyed during cooking, reducing their bioavailability.

Folic Acid (Synthetic B9)

Folic acid is the synthetic, oxidized form of Vitamin B9, manufactured for use in dietary supplements and fortified foods like bread, cereals, and pasta. It is significantly more stable than natural folate and has a higher bioavailability when consumed. However, like natural folate, it requires conversion by the body to become active methylfolate.

Methylfolate (Active B9)

Methylfolate, also known as L-methylfolate or 5-MTHF, is the active, readily usable form of Vitamin B9. Unlike folate and folic acid, it does not require enzymatic conversion and is immediately available for the body's cellular processes. It is the only form of folate that can cross the blood-brain barrier to support neurological functions, including the synthesis of mood-regulating neurotransmitters like serotonin and dopamine.

The Role of the MTHFR Gene

The body's ability to convert B9 into its active form is highly dependent on an enzyme produced by the MTHFR gene. A significant portion of the population (by some estimates, up to 40-60%) has a genetic variation, or polymorphism, in the MTHFR gene that can reduce the efficiency of this enzyme. For these individuals, converting folic acid into methylfolate can be impaired. As a result, taking a methylfolate supplement can be more effective than taking folic acid.

B9 vs. Methylfolate: A Comparison Table


Feature	Natural Folate	Folic Acid (Synthetic)	Methylfolate (Active)
Source	Naturally in food (leafy greens, legumes, eggs)	Supplements and fortified foods	Supplements (active form), produced in the body
Conversion Needed	Yes, converted to methylfolate	Yes, converted to methylfolate	No, it is the finished, usable product
Absorption	Can be less stable and absorbed less efficiently	Higher bioavailability but requires conversion	The most bioavailable form, ready for immediate use
Cost	Part of a balanced, whole food diet	Generally less expensive in supplements	Often more expensive in supplements

Who Might Benefit from Methylfolate?

While a healthy, varied diet with adequate folate is recommended for everyone, certain individuals can gain particular advantages from opting for methylfolate supplements. These include:

Individuals with MTHFR gene mutations: Those with genetic variations that hinder the conversion of folic acid.
People with mood disorders: Some studies suggest that methylfolate can enhance the effects of antidepressants and support mental health.
Women planning or during pregnancy: Adequate active folate is critical for fetal development and can help prevent neural tube defects.
Individuals with elevated homocysteine levels: Methylfolate helps convert homocysteine to methionine, a process that is important for heart health.

A Word on B12 and Folate

An important consideration when supplementing with folate is its relationship with Vitamin B12. High doses of folic acid can potentially mask the symptoms of a Vitamin B12 deficiency. This can be a serious issue because untreated B12 deficiency can cause irreversible neurological damage. To avoid this, it is recommended to test for B12 deficiency before supplementing with high-dose folate or to take a B complex supplement that contains both B9 and B12.

Food Sources of Folate

Even with supplementation, a diet rich in natural folate is always beneficial. Cooking methods can affect folate content, so raw vegetables or steaming are often preferred. Here are some of the best food sources of folate:

Leafy Greens: Spinach, kale, romaine lettuce
Legumes: Lentils, chickpeas, black-eyed peas
Vegetables: Asparagus, broccoli, Brussels sprouts, beets
Fruits: Oranges, mangoes, avocado
Eggs

Conclusion

While the terms B9, folate, folic acid, and methylfolate are all related, they are not the same. Vitamin B9 is the overarching term for this essential nutrient. Methylfolate is the active, most readily available form, and your body must convert other forms, like natural folate from food and synthetic folic acid from supplements, into methylfolate for use. For those with MTHFR gene mutations or other health concerns, direct supplementation with methylfolate may offer better absorption and utilization. Always consult a healthcare provider to determine the best form of B9 for your needs.

For more information on the different forms of folate and folic acid, please visit the official National Institutes of Health fact sheet.

Frequently Asked Questions

Yes, folate is the generic name for vitamin B9, but it refers specifically to the naturally occurring forms of the vitamin found in foods like green leafy vegetables and legumes.

Folic acid is the synthetic, inactive form of B9, while methylfolate is the active, bioavailable form. Folic acid requires an enzymatic conversion in the body to become active methylfolate.

Individuals with certain genetic mutations, particularly in the MTHFR gene, may have difficulty converting folic acid to its active form. For these people, methylfolate supplements are more effective.

Yes, a folate deficiency can lead to megaloblastic anemia, which causes symptoms like fatigue, weakness, pale skin, shortness of breath, irritability, and a sore tongue.

The MTHFR gene produces an enzyme critical for converting less active forms of folate and folic acid into the usable methylfolate. A mutation can reduce the efficiency of this process.

Excessive intake of synthetic folic acid, particularly in those with a B12 deficiency, can mask the symptoms of the B12 deficiency. If left untreated, a B12 deficiency can lead to irreversible neurological damage.

Excellent food sources of natural folate include leafy green vegetables like spinach and kale, legumes (e.g., lentils, beans), asparagus, broccoli, avocado, and eggs.

Active folate is extremely important during early pregnancy for the development of the fetal brain and spinal cord, helping to prevent neural tube defects. For this reason, many doctors recommend folic acid or methylfolate supplementation before and during pregnancy.