Is Vitamin M the Same as Folic Acid? The Truth About Folate and B9

December 17, 2025 •

4 min read

Historically, the term "vitamin M" was used as an early, outdated name for what we now commonly refer to as folic acid or vitamin B9. This distinction between the historical name and modern terminology is crucial for understanding this essential nutrient, which has both naturally occurring and synthetic forms.

Quick Summary

Explains the historical use of "vitamin M" as a name for folic acid (Vitamin B9), detailing the differences between natural folate and synthetic folic acid and their functions in the body.

Key Points

Obsolete Term: "Vitamin M" is an outdated name for folate, which is now more commonly known as Vitamin B9.
Natural vs. Synthetic: Folate is the natural form found in foods, while folic acid is the synthetic form found in supplements and fortified products.
Critical for Pregnancy: Adequate folic acid intake is crucial for pregnant women to prevent neural tube defects in developing babies.
Essential for Cell Growth: Vitamin B9 is vital for making DNA, repairing cells, and producing healthy red blood cells.
Rich Food Sources: Good sources of natural folate include leafy greens, legumes, and citrus fruits. Fortified grains are a major source of folic acid.
Supplementation for High Risk: Some individuals, such as those with certain genetic conditions or malabsorption disorders, may require specific supplementation to maintain adequate levels.

What is the history behind 'vitamin M'?

The term "vitamin M" is a historical and obsolete name for folate. It emerged during early nutritional research in the 1930s and 1940s when scientists were isolating and studying the substance. It was initially given this name after being identified as a substance that prevented a specific type of anemia in monkeys, hence the "M" designation. However, as more was learned about the chemical structure and function of the nutrient, it was reclassified as part of the B-complex vitamin family and named Vitamin B9. The name folic acid was also given to the synthetic version of this vitamin. Today, the name vitamin M is no longer used in modern medical or nutritional contexts and is only relevant for historical reference.

The crucial difference: Folic acid vs. Folate

While the terms are often used interchangeably in everyday conversation, there is a distinct and important difference between folate and folic acid. Understanding this difference is key to properly supplementing your diet and optimizing your intake of this vital nutrient. Folate refers to the various forms of vitamin B9 that occur naturally in foods, while folic acid is the synthetic form used in supplements and fortified foods.

Comparison Table: Folate vs. Folic Acid


Feature	Folate (Natural)	Folic Acid (Synthetic)
Source	Found naturally in foods	Found in supplements and fortified foods
Stability	Easily damaged by heat and light during cooking	More stable and less prone to degradation
Digestion	Processed in the small intestine	Metabolized by the liver and other tissues
Absorption	Bioavailability is less consistent; needs to be converted by the body	High bioavailability (nearly 100% on an empty stomach)
Usage	Body can use it immediately for cellular processes	Needs to be converted to usable form; can accumulate in blood if not fully metabolized

The important functions of folate (and folic acid)

Folate, in all its forms, is a water-soluble vitamin that plays several critical roles in the body. Its primary functions include:

DNA Synthesis and Repair: It is a key player in the process of making and repairing DNA, making it crucial for cell growth and division.
Red Blood Cell Production: It is essential for the production of healthy red blood cells, and a deficiency can lead to megaloblastic anemia.
Neural Tube Development: For women who are pregnant or trying to conceive, adequate intake of folic acid is paramount to prevent neural tube defects (NTDs) like spina bifida and anencephaly.
Heart Health: Folate helps to lower homocysteine levels in the blood, which may reduce the risk of heart disease and stroke.
Brain Health: Research has linked low folate levels to reduced cognitive function and an increased risk of dementia.

Dietary sources of folate and folic acid

Ensuring adequate intake of this nutrient can be achieved through both natural food sources and fortified products. Here are some examples of foods rich in folate and folic acid:

Natural Food Sources (Folate)

Leafy Green Vegetables: Spinach, romaine lettuce, asparagus, and broccoli.
Legumes: Lentils, black-eyed peas, and kidney beans.
Fruits: Citrus fruits (oranges), bananas, and papayas.
Other: Beef liver, eggs, and nuts.

Fortified Foods and Supplements (Folic Acid)

Grains: Enriched cereals, breads, pastas, and rice.
Supplements: Available as stand-alone tablets or as part of multivitamins and prenatal vitamins.

Who needs to pay special attention to folate intake?

While most people can maintain healthy folate levels through a balanced diet, certain individuals should be more mindful of their intake:

Pregnant women and women of childbearing age: Because of the critical role in preventing neural tube defects, women trying to conceive and those in the early stages of pregnancy are strongly advised to take a folic acid supplement.
Individuals with malabsorptive disorders: Conditions like Crohn's disease and celiac disease can impair folate absorption.
People with certain genetic polymorphisms: Some people have a genetic variation (MTHFR polymorphism) that affects their ability to convert folic acid into its active form, and may benefit from a different type of folate supplement.
Individuals with alcohol use disorder: Chronic alcohol use can interfere with folate absorption and metabolism.

For more detailed information on folate and its health implications, consult the NIH Office of Dietary Supplements website.

Conclusion

In summary, vitamin M is an outdated term that was an early name for folate, also known as Vitamin B9. The key takeaway is to distinguish between naturally occurring folate found in foods and the synthetic folic acid used in supplements and fortification. Both are essential for numerous bodily functions, including cell growth, red blood cell production, and preventing birth defects. For most people, a balanced diet is sufficient, but certain groups, particularly women planning pregnancy, should ensure adequate intake through fortified foods or supplements as recommended by healthcare professionals. Always consult a doctor for personalized advice on your nutritional needs.

Frequently Asked Questions

Folic acid was originally named 'vitamin M' after early research in the 1930s showed it could cure anemia in monkeys, with the 'M' standing for 'monkey'. This name is no longer used today.

The primary difference is their source and processing: folate is the naturally occurring form of Vitamin B9 found in foods, while folic acid is the synthetic, more stable version used in supplements and fortified foods.

Women who are pregnant or planning to become pregnant are advised to take a folic acid supplement to prevent neural tube defects. Other people who may require supplements include those with certain medical conditions or absorption issues.

A folate deficiency can lead to megaloblastic anemia, a condition characterized by large, abnormal red blood cells. Symptoms can include fatigue, weakness, mouth sores, and irritability.

It is extremely rare to get too much folate from food sources alone. However, high doses of synthetic folic acid from supplements can mask a Vitamin B12 deficiency and should be managed carefully.

The best form of Vitamin B9 depends on your individual needs. Most people get enough folate from a balanced diet, but those with higher needs, like pregnant women, may benefit more from highly bioavailable folic acid supplements. Consulting a healthcare provider for personalized advice is recommended.

Fortified foods are an important source of folic acid, especially in countries with mandatory fortification programs. They offer a stable and highly absorbable form of the nutrient, but a balanced diet including natural folate-rich foods is always recommended for overall health.