Folic acid is the synthetic form of the water-soluble B vitamin, Folate (Vitamin B9). This nutrient plays a fundamental role in various bodily functions, particularly cell growth and division. Folic acid is widely accessible over-the-counter (OTC). It can be easily purchased at most pharmacies, grocery stores, and online retailers without a doctor’s order.
Understanding Folic Acid and Folate
Folate is the term for Vitamin B9 found naturally in foods like leafy green vegetables, beans, and citrus fruits. Folic acid, in contrast, is the synthetic compound used in dietary supplements and for fortifying grain products. This synthetic version is chemically more stable and absorbed more efficiently than natural forms. Manufacturers prefer folic acid for supplements and fortification of flour, rice, and cereals due to this stability. Consumers typically find folic acid in stand-alone tablets, B-complex vitamins, or comprehensive multivitamin formulations, especially prenatal vitamins.
Folic acid is absorbed in the small intestine and requires conversion in the liver to become the active form, 5-methyltetrahydrofolate (5-MTHF). Due to its stability and high bioavailability, the synthetic form is the standard for supplementation, even though the body must metabolize it first. Natural polyglutamate forms of folate in food must first be broken down to a monoglutamate form before absorption.
Essential Roles of Folic Acid in Health
Folic acid’s primary function is its role as a coenzyme in single-carbon transfers, essential for the synthesis of DNA and RNA. This makes it indispensable for tissues undergoing rapid cell division and growth, such as during fetal development and red blood cell production. The supplement is well-known for its protective effect against Neural Tube Defects (NTDs), serious birth defects of the brain and spine. Adequate intake, starting at least one month before conception and continuing through the first trimester, is strongly recommended for all women who could become pregnant.
The vitamin is necessary for producing healthy red blood cells within the bone marrow. A deficiency in Vitamin B9 disrupts DNA synthesis in these rapidly dividing cells, leading to megaloblastic anemia, a condition characterized by abnormally large, immature red blood cells. Supplementation helps restore normal red blood cell maturation, resolving the anemia. Folic acid also works with Vitamin B12 and B6 to regulate levels of the amino acid homocysteine in the blood. High levels of homocysteine have been linked to an increased risk of cardiovascular disease.
Safe Use and Dosage Considerations
For most adults, the standard recommended dietary allowance (RDA) for folate is 400 micrograms (mcg) of Dietary Folate Equivalents (DFE) per day. This amount is generally considered safe for daily OTC use and is effective for preventing general deficiency. Women of childbearing age are specifically advised to consume 400 to 800 mcg of folic acid daily to ensure adequate protection against NTDs.
While OTC options are widely available, taking high doses of folic acid can be risky, particularly because it can mask an underlying Vitamin B12 deficiency. Folic acid can correct the megaloblastic anemia caused by a B12 deficiency, which removes the most noticeable warning sign of the problem. However, this correction does not halt the progressive and often irreversible nerve damage associated with untreated B12 deficiency. Therefore, a dose higher than 1,000 mcg per day should not be taken without medical guidance, especially if a B12 deficiency has not been ruled out.
Certain medications can interact with folic acid. Specifically, some anti-seizure medications, such as phenytoin and primidone, can have their effectiveness reduced if taken alongside folic acid. Conversely, some anti-seizure drugs can lower a person’s folate levels, making supplementation necessary under medical supervision.