April 7, 1998
Contact:
Moira Saucer
(202) 872-1488
INSTITUTE OF MEDICINE REPORT URGES SUPPLEMENTAL FOLIC ACID
FOR WOMEN OF CHILDBEARING AGE
Recognizing the importance of generous intakes of folic acid in the prevention of neural tube birth defects, the Institute of Medicine today released a report urging that women of childbearing age should routinely consume supplemental folic acid. The report recommends that all women of reproductive age consume 400 micrograms (mcg) of synthetic folic acid daily, "from fortified foods or supplements or a combination of the two, in addition to consuming food folate from a varied diet."
The panel also generally doubled food folate recommendations for all other Americans. Annette Dickinson, Ph.D., CRN's Director of Scientific & Regulatory Affairs, applauded the panel for increasing folate intakes across the board but said "The panel took an unduly conservative position on research supporting the ability of folic acid to reduce the incidence of heart attack and stroke. More credence should have been given to widespread support from the scientific community for alerting the public that high intakes of folic acid may reduce their risk of heart disease." The ability of folic acid to lower homocysteine levels--now a recognized risk factor for heart attacks and stroke--is well established, she observed.
Developed by the panel on folate and other B vitamins, the report sets forth new RDAs or other values for eight B vitamins and choline. In recommendations related to vitamin B12, the panel said that people over the age of 50 should obtain most of their recommended intake of 2.4 micrograms daily from fortified foods or supplements. Between 10 and 30 percent of older adults have lost the ability to absorb the naturally occurring form of B12 found in food. While Dr. Dickinson applauded the report's authors for recognizing that the elderly require supplemental B12, she observed that "Supplemental B12 levels for the elderly recommended by the report of 2.4 mcg a day are much too low. At least 100 mcg may be needed, in people with an absorption problem."
The panel set the tolerable upper level (UL) for vitamin B6 at 100 milligrams per day for adults. Calling this value "conservative but not generally inappropriate," John Hathcock, Ph.D., CRN's Director of Nutritional & Regulatory Science said that the data suggest that this UL is somewhat lower than needed to assure safety. "The fact that this major new scientific analysis by the National Academy of Sciences identified 100 milligrams of vitamin B6 as safe for daily consumption has important international implications. The United Kingdom is proposing legislation that would inappropriately limit vitamin B6 supplements sold as food to 10 milligrams per day. This new report provides the most up-to-date scientific analysis and highlights the unfounded basis on which the UK proposal is based."
However, Hathcock criticized as "unjustified" the tolerable upper level for niacin, established by the panel at 35 milligrams per day. The UL, he said, is based on an old study involving "flushing," which is a common reaction to niacin. "While flushing is a nuisance," he said, "it can hardly be characterized as an adverse reaction, and it goes away as tolerance develops." He added, "This UL decision effectively ignores a double-blind, placebo-controlled clinical intervention trial that found no adverse effects whatever from 500 milligrams of supplemental niacin per day."
While the panel did recommend higher intakes for folate and B12, most intake levels did not change appreciably. For a comparison, see the attached chart.
Dietary Reference Intakes: Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline is the second in an IOM series to establish new recommendations for nutrient intakes for Americans and Canadians and builds on the RDAs issued periodically by the National Academy of Sciences since 1941.
FOOD AND NUTRITION BOARD NATIONAL ACADEMY OF SCIENCES INSTITUTE OF MEDICINE
RECOMMENDED LEVELS FOR INDIVIDUAL INTAKE
WOMEN, AGES 19 TO 50NUTRIENT New RDA Old RDA
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Thiamin (mg/d) 1.1 1.1
Riboflavin (mg/d) 1.1 1.3
Niacin (mg/d as niacin equi 14 15
B6 (mg/d) 1.3 1.6
Folic Acid (microg/d) Diet, plus 400 microg
synthetic folic acid 180
B12 (microg/d) 2.4 2OLD Estimated Safe
NUTRIENT New Adequate & Adequate Daily
Dietary Intake (ESADDI)
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Pantothenic Acid (mg/d) 5 4 to 7
Biotin (microg/d) 30 30 to 100
Choline (mg/d) 425 no recommendationSource: Dietary Reference Intakes: Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline, National Academy of Sciences.
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