Folate: What is it?

Folate is a water-soluble B vitamin that occurs naturally in food. Folic acid is the synthetic form of folate that is found in supplements and added to fortified foods.

Folate gets its name from the Latin word "folium" for leaf. A key observation of researcher Lucy Wills nearly 70 years ago led to the identification of folate as the nutrient needed to prevent the anemia of pregnancy. Dr. Wills demonstrated that the anemia could be corrected by a yeast extract. Folate was identified as the corrective substance in yeast extract in the late 1930s, and was extracted from spinach leaves in 1941.

Folate helps produce and maintain new cells. This is especially important during periods of rapid cell division and growth such as infancy and pregnancy. Folate is needed to make DNA and RNA, the building blocks of cells. It also helps prevent changes to DNA that may lead to cancer. Both adults and children need folate to make normal red blood cells and prevent anemia. Folate is also essential for the metabolism of homocysteine, and helps maintain normal levels of this amino acid.

What foods provide folate?

Leafy green vegetables (like spinach and turnip greens), fruits (like citrus fruits and juices), and dried beans and peas are all natural sources of folate.

In 1996, the Food and Drug Administration (FDA) published regulations requiring the addition of folic acid to enriched breads, cereals, flours, corn meals, pastas, rice, and other grain products. Since cereals and grains are widely consumed in the U.S., these products have become a very important contributor of folic acid to the American diet. The following table suggests a variety of dietary sources of folate.

Table 1: Selected Food Sources of Folate and Folic Acid

Food	Micrograms (μg)	% DV^
*Breakfast cereals fortified with 100% of the DV, ¾ cup	400	100
Beef liver, cooked, braised, 3 ounces	185	45
Cowpeas (blackeyes), immature, cooked, boiled, ½ cup	105	25
*Breakfast cereals, fortified with 25% of the DV, ¾ cup	100	25
Spinach, frozen, cooked, boiled, ½ cup	100	25
Great Northern beans, boiled, ½ cup	90	20
Asparagus, boiled, 4 spears	85	20
*Rice, white, long-grain, parboiled, enriched, cooked, ½ cup	65	15
Vegetarian baked beans, canned, 1 cup	60	15
Spinach, raw, 1 cup	60	15
Green peas, frozen, boiled, ½ cup	50	15
Broccoli, chopped, frozen, cooked, ½ cup	50	15
*Egg noodles, cooked, enriched, ½ cup	50	15
Broccoli, raw, 2 spears (each 5 inches long)	45	10
Avocado, raw, all varieties, sliced, ½ cup sliced	45	10
Peanuts, all types, dry roasted, 1 ounce	40	10
Lettuce, Romaine, shredded, ½ cup	40	10
Wheat germ, crude, 2 Tablespoons	40	10
Tomato Juice, canned, 6 ounces	35	10
Orange juice, chilled, includes concentrate, ¾ cup	35	10
Turnip greens, frozen, cooked, boiled, ½ cup	30	8
Orange, all commercial varieties, fresh, 1 small	30	8
*Bread, white, 1 slice	25	6
*Bread, whole wheat, 1 slice	25	6
Egg, whole, raw, fresh, 1 large	25	6
Cantaloupe, raw, ¼ medium	25	6
Papaya, raw, ½ cup cubes	25	6
Banana, raw, 1 medium	20	6

* Items marked with an asterisk (*) are fortified with folic acid as part of the Folate Fortification Program.

^ DV = Daily Value. DVs are reference numbers developed by the Food and Drug Administration (FDA) to help consumers determine if a food contains a lot or a little of a specific nutrient. The DV for folate is 400 micrograms (μg). Most food labels do not list a food's magnesium content. The percent DV (%DV) listed on the table indicates the percentage of the DV provided in one serving. A food providing 5% of the DV or less is a low source while a food that provides 10-19% of the DV is a good source. A food that provides 20% or more of the DV is high in that nutrient. It is important to remember that foods that provide lower percentages of the DV also contribute to a healthful diet.

What are the Dietary Reference Intakes for folate?

Recommendations for folate are given in the Dietary Reference Intakes (DRIs) developed by the Institute of Medicine of the National Academy of Sciences. Dietary Reference Intakes is the general term for a set of reference values used for planning and assessing nutrient intake for healthy people. Three important types of reference values included in the DRIs are Recommended Dietary Allowances (RDA), Adequate Intakes (AI), and Tolerable Upper Intake Levels (UL). The RDA recommends the average daily intake that is sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals in each age and gender group. An AI is set when there is insufficient scientific data available to establish a RDA. AIs meet or exceed the amount needed to maintain a nutritional state of adequacy in nearly all members of a specific age and gender group. The UL, on the other hand, is the maximum daily intake unlikely to result in adverse health effects.

The RDAs for folate are expressed in a term called the Dietary Folate Equivalent. The Dietary Folate Equivalent (DFE) was developed to help account for the differences in absorption of naturally occurring dietary folate and the more bioavailable synthetic folic acid. Table 2 lists the RDAs for folate, expressed in micrograms (μg) of DFE, for children and adults.

Table 2: Recommended Dietary Allowances for Folate for Children and Adults

Age (years)	Males and Females (μg/day)	Pregnancy (μg/day)	Lactation (μg/day)
1-3	150	N/A	N/A
4-8	200	N/A	N/A
9-13	300	N/A	N/A
14-18	400	600	500
19+	400	600	500

*1 DFE = 1 μg food folate = 0.6 μg folic acid from supplements and fortified foods

There is insufficient information on folate to establish an RDA for infants. An Adequate Intake (AI) has been established that is based on the amount of folate consumed by healthy infants who are fed breast milk . Table 3 lists the Adequate Intake for folate, in micrograms (μg), for infants.

Table 3: Adequate Intake for folate for infants

Age (months)	Males and Females (μg/day)
0 to 6	65
7 to 12	80

The National Health and Nutrition Examination Survey (NHANES III 1988-94) and the Continuing Survey of Food Intakes by Individuals (1994-96 CSFII) indicated that most individuals surveyed did not consume adequate folate. However, the folic acid fortification program, which was initiated in 1998, has increased folic acid content of commonly eaten foods such as cereals and grains, and as a result most diets in the United States (US) now provide recommended amounts of folate equivalents.

When can folate deficiency occur?

A deficiency of folate can occur when an increased need for folate is not matched by an increased intake, when dietary folate intake does not meet recommended needs, and when folate excretion increases. Medications that interfere with the metabolism of folate may also increase the need for this vitamin and risk of deficiency.

Medical conditions that increase the need for folate or result in increased excretion of folate include:

• pregnancy and lactation (breastfeeding)
• alcohol abuse
• malabsorption
• kidney dialysis
• liver disease
• certain anemias

Medications that interfere with folate utilization include:

• anti-convulsant medications (such as dilantin, phenytoin and primidone)
• metformin (sometimes prescribed to control blood sugar in type 2 diabetes)
• sulfasalazine (used to control inflammation associated with Crohn's disease and ulcerative colitis)
• triamterene (a diuretic)
• methotrexate (used for cancer and other diseases such as rheumatoid arthritis)
• barbiturates (used as sedatives)