What Is Vitamin B9 Also Known As?

November 17, 2025 •

4 min read

The human body cannot produce vitamin B9, making it an essential nutrient that must be obtained through diet or supplementation. This vital B vitamin is also known by the names folate and folic acid, each having distinct characteristics and functions within the body. Understanding these forms is key to ensuring adequate intake for your health.

Quick Summary

Vitamin B9 is most commonly known as folate, its natural form, and folic acid, its synthetic form. Both are essential for key bodily functions, including DNA synthesis and red blood cell production, with folic acid being crucial during pregnancy. Their differences lie in their source and bioavailability.

Key Points

Two Primary Forms: Vitamin B9 is known as folate (natural, from food) and folic acid (synthetic, in supplements and fortified foods).
Essential for DNA: Both folate and folic acid are crucial for DNA synthesis, cell growth, and tissue repair.
Prevents Birth Defects: Folic acid supplementation is vital during early pregnancy to prevent neural tube defects like spina bifida.
Different Bioavailability: The body absorbs synthetic folic acid more efficiently than natural food folate.
Rich Food Sources: Excellent sources of folate include leafy greens, legumes, and citrus fruits, while fortified cereals provide folic acid.
Risk of Deficiency: Deficiency can cause megaloblastic anemia, leading to fatigue, weakness, and other symptoms.

Folate vs. Folic Acid: The Two Forms of Vitamin B9

The Fundamental Difference

At its core, what is vitamin B9 also known as? Vitamin B9 is the umbrella term for a family of water-soluble compounds, most notably folate and folic acid. The main distinction is in their origin: folate is the form found naturally in foods, while folic acid is the synthetic, man-made version added to fortified foods and supplements. Though often used interchangeably, this difference has significant implications for how the body absorbs and uses the nutrient. Studies show that folic acid from supplements and fortified foods is absorbed more efficiently by the body than the folate found naturally in foods.

The Crucial Role of Vitamin B9

Both folate and folic acid are integral to many of the body's processes. One of their most critical functions is in one-carbon metabolism, which is essential for synthesizing and repairing DNA and RNA. This makes it a vital nutrient for all cells, especially during periods of rapid growth and cell division, such as infancy, adolescence, and pregnancy. Other important roles include:

Red Blood Cell Formation: Vitamin B9 is required for producing healthy red blood cells, which carry oxygen throughout the body. A deficiency can lead to a condition called megaloblastic anemia.
Reducing Homocysteine Levels: Folate works with vitamin B12 to convert homocysteine, an amino acid, into methionine. Elevated homocysteine levels are associated with an increased risk of heart disease and stroke, and supplementing with folic acid can help lower these levels.
Mental and Emotional Health: Low levels of folate have been linked to depression and poor cognitive function. While research is ongoing, some studies suggest that supplementing with folate may help improve symptoms in some people with depression.

The Importance of Folic Acid in Pregnancy

For women of childbearing age, and especially for those who are pregnant or planning to become pregnant, folic acid is profoundly important. Adequate intake is essential for preventing serious congenital irregularities of the fetal brain and spine, known as neural tube defects (NTDs), including spina bifida. Since NTDs can occur within the first few weeks of pregnancy—often before a woman even knows she is pregnant—many health organizations recommend that all women who could become pregnant take 400 mcg of folic acid daily.

Deficiency and Dietary Sources

A deficiency in vitamin B9, while less common in countries with mandatory food fortification, can still occur. Certain groups, such as those with alcohol use disorder, malabsorptive disorders (like celiac disease), and some genetic polymorphisms, are at a higher risk. Symptoms of folate deficiency can include:

Fatigue and weakness
Irritability
Headaches
Sore or swollen tongue
Mouth sores or ulcers
Heart palpitations
Shortness of breath

Luckily, vitamin B9 is found in a wide variety of foods. To get sufficient amounts, incorporating foods from this list can be beneficial:

Leafy Greens: Spinach, asparagus, broccoli, and Brussels sprouts.
Legumes: Lentils, peas, and kidney beans are excellent sources.
Fruits: Oranges, bananas, and papayas.
Animal Products: Beef liver and eggs are rich in natural folate.
Fortified Grains: Many breads, cereals, and pastas are enriched with folic acid.

Comparison: Folate vs. Folic Acid


Feature	Folate (Natural)	Folic Acid (Synthetic)
Source	Found naturally in various foods like leafy greens, legumes, and fruits.	Added to supplements and fortified foods, such as cereals and flour.
Bioavailability	Approximately 50% absorbed by the body.	Better absorbed by the body, with a bioavailability of up to 85% when taken with food.
Stability	Less stable and sensitive to heat, light, and oxygen, meaning content can decrease during cooking or storage.	More stable and less susceptible to degradation from heat and light, making it ideal for food fortification.
Metabolism	Metabolized primarily in the intestinal mucosa.	Requires conversion by the enzyme dihydrofolate reductase in the liver.

How to Ensure Adequate Intake

For most people, a balanced diet rich in folate-containing foods is sufficient. However, for those at a higher risk of deficiency or women who are pregnant or planning to be, supplementation with folic acid is often recommended. Always consult a healthcare professional before starting any new supplement regimen, as high doses of folic acid can sometimes mask a vitamin B12 deficiency, potentially leading to neurological complications if left unaddressed.

For more information on folate and folic acid, visit the National Institutes of Health Fact Sheet for Health Professionals.

Conclusion

In summary, what is vitamin B9 also known as is not a simple one-word answer. It refers to both folate, the form found naturally in foods, and folic acid, its synthetic version used in fortification and supplements. Both are essential for fundamental biological processes, from DNA synthesis to red blood cell production. While most people can meet their needs through a varied diet, certain groups benefit from supplementation. Being aware of the distinction between folate and folic acid, as well as the importance of maintaining adequate levels, is a crucial step towards better health.

Frequently Asked Questions

No, folate is the naturally occurring form of Vitamin B9 found in foods, while folic acid is the synthetic, or man-made, version used in fortified foods and dietary supplements.

The main function of vitamin B9 is to help the body produce and repair DNA, form healthy red blood cells, and facilitate cell growth and function. It is essential for many key metabolic processes.

During pregnancy, adequate vitamin B9 intake is critical for proper fetal development. It helps prevent major birth defects of the brain and spine, known as neural tube defects.

Many foods are rich in folate, including dark leafy green vegetables like spinach and kale, legumes (beans, peas, and lentils), citrus fruits (oranges and grapefruits), and eggs.

Symptoms of a vitamin B9 deficiency can include fatigue, weakness, shortness of breath, irritability, headaches, and sores in the mouth or on the tongue. Severe deficiency can lead to anemia.

It is unlikely to consume excessive amounts of folate from food alone. However, very high intakes of supplemental folic acid can potentially mask a vitamin B12 deficiency, which can cause neurological damage if not properly diagnosed and treated.

Healthcare professionals often recommend a folic acid supplement for pregnant women, women planning to become pregnant, and individuals with certain medical conditions or a family history of neural tube defects.

While folate from food is healthy, synthetic folic acid is more bioavailable and therefore absorbed more effectively by the body. For preventing neural tube defects and addressing deficiencies, folic acid supplementation is often the recommended form.