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How Much Folic Acid Is Needed Daily?

Folates are essential B-vitamins. Folic acid is the synthetic form of naturally occurring folates found in green leafy vegetables, fruits and certain beans. Folic acid has been added to various staple foods in countries that have implemented dietary fortification programs. This allows a population that would not consume adequate levels of natural folates to obtain beneficial levels of folic acid. These levels ultimately vary depending on diet, age and reproductive status.

  1. Natural Folate

    • The word folate is rooted in the word foliage; specifically, it was first isolated from spinach leaves as the substance that cured certain anemias. Folates are also found in a variety of other foods: oranges, asparagus and lentils. Once the chemical structures of natural folates were determined, a synthetic form was made in the lab and termed folic acid. Folic acid was then used to treat anemia, and later to decrease the risk of birth defects.

    Dietary Folate Equivalents

    • As the use of folic acid became more widespread, it was noted that folic acid was absorbed and available to the body at a higher level than natural folates. The Food and Nutrition Board of the Institute of Medicine therefore set a new dietary recommendation for folates and introduced the Dietary Folate Equivalent (DFE). These equivalents indicate that natural folates count for 1 equivalent, while synthetic forms equate to 1.7 to 2.0 equivalents. This has resulted in the Recommended Dietary Allowance (RDA) for folate being reported in DFE.

    Recommended Dietary Allowance

    • The suggested intake of folates or folic acid varies depending on age and reproductive health. During the first year of life, adequate intake for folates in DFE is 65 to 80 micrograms a day. This increases to 150 micrograms for toddlers and 200 and 300 for ages 4 to 8 and 9 to 13 years, respectively. The RDA for adolescents and adults is 400 micrograms a day. However, when attempting to become pregnant and during pregnancy, the RDA is typically doubled to 600 to 800 micrograms a day.

    Deficiency

    • Folate deficiency has been associated with the occurrence of selected birth defects, and a considerable number of human studies have demonstrated the protective role of maternal folic acid supplementation. Numerous studies have shown that maternal folic acid supplementation reduces the incidence of neural tube birth defects by 40% to 70%. However, despite the accumulating evidence regarding the protective effect of folate, the mechanism by which this is achieved remains unknown.

    Expert Insight

    • The fortification of folic acid in the food supply has decreased the risk of birth defects in treated populations. Such fortification also affects heart disease and cancer risks. By understanding and maintaining adequate folate levels, by following established RDAs, the risk for these diseases can be decreased, and the economic and biological impacts fully realized in fortified populations.

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