Folic Acid Sources and Dosage Recommendations
Foods and Recommended Dosage for Folic Acid Deficiency
Nov 21, 2008
The terms folate and folic acid relate to different sources of this B vitamin. Folate is the food form while folic acid is the supplement form and the form used in food fortification. However, the most commonly used term is folic acid.
Folic Acid Foods
Folic acid is widely distributed in foods but it is present in low levels. Except for liver, most foods provide only small amounts of folic acid. The following foods are good folic acid sources:
- Green leafy vegetables - three or more servings a day may be required to prevent folic acid deficiency
- Fruits- especially citrus fruits and juice
- Dried beans and peas (legumes)
- Fortified breads, cereals, flours, pasta and rice.
"Humans need to absorb approximately 50-100mcg of folate per day in order to replenish the daily degradation and loss through urine and bile. Otherwise, signs and symptoms of deficiency can manifest after 4 months," states Angela Gentili in the online eMedicine article ‘Folic Acid Deficiency.’
The bioavailability of folic acid in foods varies with different foods. However, 50-100 micrograms (mcg) per day might equate to eating 1/2 a cup of fortified breakfast cereal, green leafy vegetables or chickpeas a day.
Unfortunately, it is not that simple. Many factors affect the absorption and metabolism of folic acid including vitamin or mineral deficiencies, alcoholism, aging and more. Additionally, even before foods with folic acid are eaten the levels may already have diminished by 50% to 95%. Harvesting, storage, distribution, and cooking can cause considerable losses of folic acid from foods. This is why pregnant women, for example, are recommended to take folic acid supplements, at the level of 400mcg, before they conceive. Folic acid supplements are more stable with 100% bioavailability.
Folic Acid Recommended Dosage
The dietary reference intakes, published online by the Institute of Medicine of the National Academies are:
- From 14 years old: 400mcg per day
- In pregnancy: 600mcg per day
- During lactation: 500mcg per day
The tolerable upper intake level (UL), which is the maximum level of daily nutrient intake likely to pose no risk of adverse effects, is between 800 to 1000mcg (1mg).
In cases of deficiency, taking folic acid supplements containing 400mcg to 1000mcg once a day can replenish tissue stores.
It is worth noting that high amounts of folic acid may mask a vitamin B12 deficiency and if left untreated can cause neurological damage. Folic acid supplements that include vitamin B12 are readily available.
Resources:
Gropper S, Smith JL, Groff JL. Advanced nutrition and human metabolism. Belmont, CA: Thomson Wadsworth; 2005.
Johnson LE. Folate [monograph on online] 2007 April [cited 2008 November]; Available from: www.merck.com
World Health Organization. Folate and Folic Acid In: Vitamin and Mineral Requirements in Human Nutrition. [chapter online] 2004 [cited 2008 November]
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