What is the deficiency disease of vitamin M?

November 1, 2025 •

3 min read

In the 1930s, researchers identified a nutrient that prevented anemia in monkeys, which they designated as vitamin M. Today, we know that vitamin M is simply the historical name for folic acid, or vitamin B9, and its deficiency can lead to significant health problems.

Quick Summary

This article explains that vitamin M is an outdated term for folic acid (vitamin B9), and its deficiency can result in megaloblastic anemia and severe birth defects. It explores the symptoms, causes, diagnosis, and treatment for this nutritional shortfall.

Key Points

Vitamin M is Folic Acid: The term “vitamin M” is an outdated name for Folic Acid, also known as Vitamin B9.
Causes Megaloblastic Anemia: A deficiency in folic acid primarily causes megaloblastic anemia, a blood disorder characterized by large, immature red blood cells.
Risk of Neural Tube Defects: Insufficient folic acid intake during early pregnancy can lead to severe birth defects of the brain and spine, such as spina bifida.
Symptoms Include Fatigue and Paleness: Common signs of a deficiency are persistent fatigue, weakness, pale skin, shortness of breath, and a sore tongue.
Easily Prevented and Treated: Folic acid deficiency is preventable and treatable through a diet rich in folate and, when necessary, supplements.

What Exactly Is Vitamin M?

The term "vitamin M" is a historical name for folic acid, also known as vitamin B9. It was first used in the 1930s following studies in monkeys that developed anemia. This term was later replaced by folic acid as the specific compound was identified and characterized. Therefore, a discussion of vitamin M deficiency is a discussion of folic acid deficiency.

Megaloblastic Anemia: The Primary Deficiency Disease

The main consequence of folic acid (vitamin M) deficiency is megaloblastic anemia. This condition involves the production of unusually large, underdeveloped red blood cells, which are also fewer in number and often oval-shaped. These cells are less effective at transporting oxygen, leading to reduced oxygen supply to the body's tissues and organs. Symptoms of megaloblastic anemia include:

Chronic Fatigue and Weakness
Pale Skin
Shortness of Breath
Neurological Symptoms: Such as irritability, confusion, and memory issues, though these are more often linked to vitamin B12 deficiency.
Gastrointestinal Issues: Including diarrhea, loss of appetite, and weight loss.
Oral Manifestations: A severe deficiency can cause glossitis (a swollen, red tongue) and mouth sores.

The Critical Role in Pregnancy and Neural Tube Defects

Folic acid (vitamin M) deficiency is particularly critical during pregnancy due to its role in fetal development. Adequate folate is essential for the formation of the neural tube, which develops into the baby's brain and spinal cord. The neural tube closes early in pregnancy. A deficiency during this period can prevent complete closure, leading to neural tube defects (NTDs). These include:

Spina Bifida: Involves improper formation of the fetal spine and spinal cord.
Anencephaly: A severe condition where major parts of the brain and skull are absent, which is fatal.

Due to these risks, health organizations recommend that women who are pregnant or planning to become pregnant take a daily folic acid supplement.

Folate vs. Folic Acid: A Comparison

While often used interchangeably, folate and folic acid have key differences.


Feature	Folate	Folic Acid
Nature	Naturally found in foods.	Synthetic form.
Absorption	Processed in the small intestine; variable absorption.	More stable and generally better absorbed.
Primary Source	Leafy greens, legumes, citrus fruits, liver.	Supplements and fortified foods (breads, cereals).
Stability	Degrades with heat and light.	Highly stable.
Function	Needs conversion to L-5-methylTHF.	Converted by the liver and other tissues.

Diagnosis, Treatment, and Prevention

Folic acid deficiency is diagnosed with blood tests measuring folate levels. Vitamin B12 levels are also typically checked as deficiencies can coexist and have similar symptoms. Treating a B12 deficiency solely with folic acid can mask neurological damage progression.

Treatment usually involves oral folic acid supplements, with dosage varying based on the deficiency's severity. Daily supplements are often sufficient for adults, while pregnant women or those with specific conditions may need higher doses.

Prevention includes a diet rich in folate from foods like leafy green vegetables, citrus fruits, and legumes. Fortifying grain products with folic acid, as done in countries like the U.S., has also reduced deficiency rates. The CDC advises all women of childbearing age to consume 400 micrograms of folic acid daily.

Conclusion

Vitamin M, now known as folic acid or vitamin B9, is a vital nutrient. Its deficiency can lead to megaloblastic anemia, causing fatigue and weakness. For pregnant individuals, insufficient folate is a serious risk factor for neural tube defects. The deficiency is preventable and treatable through diet and supplementation. Proper diagnosis and treatment are crucial to manage the condition and prevent complications. The history of vitamin M highlights the impact of nutritional science and public health efforts in preventing deficiency diseases. For further details, consult the CDC's resources on folic acid.

Frequently Asked Questions

The primary deficiency disease of vitamin M, which is now known as folic acid or vitamin B9, is megaloblastic anemia.

The term 'vitamin M' was used historically but is no longer common because scientists later identified the specific compound responsible for its effects as folic acid, or vitamin B9.

Early signs of folic acid deficiency can be subtle but often include fatigue, weakness, pallor, and a general lack of energy.

A lack of folic acid during early pregnancy significantly increases the risk of neural tube defects (NTDs), which are serious birth defects affecting the baby’s brain and spinal cord.

Folate is the naturally occurring form of vitamin B9 found in foods, while folic acid is the synthetic, man-made form found in supplements and fortified foods.

Excellent food sources of natural folate include leafy green vegetables like spinach, legumes, citrus fruits, eggs, and liver.

Pregnant women, people with poor diets, those with alcohol use disorder, and individuals with malabsorption disorders like celiac disease are at a higher risk of folic acid deficiency.

No, while supplements are the most common treatment, increasing your intake of folate-rich foods is also crucial for management and prevention. Some countries fortify grain products with folic acid.