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living in a country where vitamin A deficiency source for vitamin A is liver. All other foods Liver makes
is common? containing preformed vitamin A need to be
consumed in atypically large amounts in order a unique
LIVER FOR VITAMIN A to meet the vitamin A requirement. Only 10–15 contribution
In 2015, the European Food Safety Author- g [1/2 ounce] of animal liver is necessary to meet to the
ity set population reference intakes at 650 μg the daily requirement, demonstrating that liver
(2170 IU) for non-pregnant women and 700 μg is the most important source of vitamin A for diet—that of
(2333 IU) during pregnancy. The German Nutri- humans.” Other foods like meat, butter, eggs easily
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tion Society recommends a 40 percent increase and milk only contribute a small portion (less satisfying
in vitamin A intake for pregnant women equal than 20 percent) of dietary preformed vitamin
to 1100 μg RAE (3670 IU). Unfortunately, A. We would agree that liver makes a unique vitamin A
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“pregnant women or those considering becom- contribution to the diet—that of easily satisfying needs.
ing pregnant are generally advised to avoid the vitamin A needs.
intake of vitamin A-rich liver and liver foods, The UK and Australian guidelines state
based upon unsupported scientific findings. As that evidence is lacking to support routine
a result, the provitamin A carotenoid β-carotene supplementation of vitamin A and that exces-
remains their essential source of vitamin A.” sive quantities of fat-soluble vitamins may
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“The average intake of β-carotene in cause harm. They go further to recommend
Germany is about 1.5–2 mg a day. . . the total that pregnant women avoid consuming liver and
vitamin A contribution from β-carotene intake liver products. 22,23,24
represents 10–15 percent of the RDA.” Without While true that “excessive” quantities of
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sources of retinol, it is highly unlikely German fat-soluble vitamins can be harmful, does the
women will meet these recommendations. Com- practice of eating four ounces of liver weekly
pared to other foods, “the only relevant dietary lead to an excessive intake of vitamin A? A

VITAMIN A SUPPLEMENTATION FOR PREGNANT WOMEN?

The assumption that the vitamin A intakes of pregnant women in the U.S. are more than adequate is widespread.
Between 1981 and 1989, the reported average intakes in studies of pregnant women ranged from 711 to 1440 RE (2,370
to 4800 IU), which exceeded the then RDA of 800 retinol equivalents (RE) similar to the current RDA of 770 RAE (al-
1
though REs were quantified using the more liberal conversion factors for carotenoids to retinol, which have been shown
to be overestimated by at least a factor of two). Today, the average dietary intake among females nineteen to thirty years
is 515 RAE (1720 IU) which may represent a 50 percent decrease from the 1980s, or could reflect the more accurate
2
conversion factor used today. In 2001 the IOM recommended a new unit, the retinol activity equivalent (RAE). Each μg
RAE corresponds to 1 μg retinol, 2 μg of β-carotene in oil, 12 μg of “dietary” beta-carotene, or 24 μg of the three other
dietary provitamin-A carotenoids. 3
In 1990, the Food and Nutrition Board of the IOM recommended “carefully supervised supplementation” for cer-
tain at-risk groups of pregnant women, stressing that “supplementation of vitamin A should be approached with caution
until the risk is clarified.” This recommendation came prior to the Rothman study (see sidebar, page 20), which argued
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against the use of vitamin A by pregnant women, yet there were already some indications that large doses of vitamin A
were problematic—chiefly based upon outcomes in women who took the acne medication Isotretinoin during the first
trimester. At that time, most scientists suggested that an intake of at least 20,000 to 50,000 IU per day was associated
with an increased risk for birth defects.
A few researchers have made efforts to draw attention to this issue. It is “in our opinion rather likely, that a significant
portion of the low-income population in some of the most industrialized countries suffers from undiagnosed low vitamin
A status. Women in these populations. . . would benefit from a safely designed vitamin A supplementation protocol. How-
ever, to our knowledge, there has been no attempt to identify these women or to correct their nutritional deficiencies.” 4,5

1. Committee on Nutritional Status During Pregnancy and Lactation, Institute of Medicine, ed. Nutrition During Pregnancy: Part II: Nutrient Supplements. Washington,
US: National Academies Press, 1990. http://www.nap.edu/download/1451
2. Scientific Report of the 2015 Dietary Guidelines Advisory Committee. Part E.Section 2.1. Appendix E-2.1: Usual Intake Distributions, 2007-2010, by Age/Gender
Groups. http://health.gov/dietaryguidelines/2015-BINDER/meeting2/docs/refMaterials/Usual_Intake_072013.pdf
3. Dietary reference intakes for vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganes(TRUNCATED), 2001, National Academy Press, Wash-
ington, D.C. http://www.nap.edu/read/10026/chapter/6#141
4. Azaïs-Braesco V.Pascal G. Vitamin A in pregnancy: requirements and safety limit. Am J Clin Nutr. 2000;71:1325S-1333S.
5. Stephens D, Jackson PL, Gutierrez Y. Subclinical vitamin A deficiency: a potentially unrecognized problem in the United States. Pediatr Nurs 1996;22:377–89.
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