Found in food sources, folate is a water-soluble vitamin that is part of the vitamin B complex. Because it dissolves in water, this vitamin can be easily lost during preparation and processing, which indicates that gentle cooking methods[1] should be preferred. Also, water-soluble vitamins are readily excreted when consumed in excess, meaning that very little is stored in the body. Thus, they should be consumed daily in order to address bodily demands.
The synthetic form of folate is called folic acid and is more readily absorbed than natural forms of folate. According to the FDA[2], all enriched grain products should be fortified with folic acid. This is because during the milling process, the vitamin-rich outer layers of the grain (germ, bran and husk) are discarded in order to improve the taste and texture of the final product (refined grain). Consequently, to prevent deficiency diseases, folic acid (together with other B vitamins and iron) is added to many processed goods such as ready-to-eat cereals, rice, pasta, and flour.
Folate is an important nutrient that participates in DNA synthesis and in the formation of red blood cells. Folate deficiency impairs red blood cell synthesis, causing a specific type of anemia. White blood cell formation may also be affected as well as cellular division throughout the body. Additional symptoms are heartburn, diarrhea, red tongue (inflammation), depression, poor growth, and mental confusion. Folate deficiency has also been linked to increased risk of heart disease, stroke, and certain cancers. Moreover, deficiency of folate during pregnancy may lead to birth defects in the fetus.
Even though folate deficiency is not common among healthy adults, older people with inadequate food intake, people following restrictive diets, and people with alcoholism may be at increased risk. In healthy populations, changes in red blood cells may occur after seven to 16 weeks without folate. However, some people may present a genetic defect that disturbs the metabolism of folate, which considerably increases the person’s daily needs for folate.
The RDA[3] of folate for adults is 400 micrograms per day. However, pregnant women need extra folate to support the growth of the fetus. The Upper Level for folate is 1,000 micrograms per day when it comes from the synthetic form (folic acid). Consuming large doses of folic acid (usually through supplements) may cause toxic effects such as diarrhea, insomnia, and irritability and can also mask a vitamin B12 deficiency. The folate naturally occurring in foods, on the other hand, is not likely to cause any harm because it has limited absorption in the body.
The richest sources of folate are green, leafy vegetables, organ meats, sprouts, dried beans, and orange juice. However, folate is a delicate nutrient and may be destroyed by heat. Thus, eating fresh fruits and raw vegetables is recommended. If you must cook, use minimal water and gentle methods such as steaming, stir-frying, and microwaving. Enriched foods should display the Daily Values for folate on the product label. When comparing pre-packed products, keep in mind that 5% or less is considered low, while 20% or more is considered high.
References
Boyle, M. and Long, S. Personal Nutrition. Belmont, CA: Wadsworth Cengage Learning. 2010.
Wardlaw, G. and Smith, A. Contemporary Nutrition. New York: McGraw-Hill. 2009.