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OCR for page 237
11
Introduction
In addition to increased energy requirements during pregnancy, a topic
covered in Part I of this volume, it has long been recognized that pregnancy
also increases a woman's need for protein, vitamins, and minerals. Some re-
ports suggest that the usual dietary intake of certain nutrients is inadequate
to meet the needs of pregnant women, and many suggest that supplemental
intake of one or more nutrients might be desirable. Recently, health care
providers have asked for guidance in counseling pregnant women about
the use of nutrient supplements with regard to their safety, efficacy, and
appropriate dosage if used.
In the past, several reports issued by expert Food and Nutrition Board
(FNB) committees on maternal nutrition have given detailed consideration
to certain vitamins, minerals, and protein. One of these reports contained
an overview of laboratory indices of a broad spectrum of nutrients (NRC,
1978~; another covered certain practices, such as pica (the ingestion of
nonfood substances such as laundry starch) and vegetarianism, that may
influence nutritional status during pregnancy (NRC, 1982~. Four reports
recommended 30 to 60 mg of supplemental iron per day (NRC, 1970, 1980,
1981, 1982), and two recommended supplemental folic acid (NRC, 1970,
1980) during pregnancy as a means of reducing the risk of anemia. No
FNB reports have recommended the routine use of multivitamin-mineral
supplements.
237
OCR for page 238
238
DIETARY INTAKE AND NUTRIENT SUPPLEMENTS
PREVIOUS RECOMMENDATIONS FROM
PROFESSIONAL ORGANIZATIONS
Professional organizations concerned with maternal and child health
have made recommendations pertaining to nutrient intake and supplement
use during pregnancy. For example, a special task force of the American
Dietetic Association released the following statement regarding vitamin and
mineral supplementation. Although this statement was targeted toward the
general population, it specifically mentions pregnant women:
Healthy children and adults should obtain adequate nutrient intakes from
dietary sources. Meeting nutrient needs by choosing a vanes of foods in
moderation, rather than by supplementation, reduces the potential risk for
both nutrient deficiencies and nutrient excesses. Individual recommendations
regarding supplements and diets should come from physicians and registered
dietitians. Supplement usage may be indicated in some circumstances including:
Women who are pregnant or breastteeding need more of certain nutnents,
especially iron, folio add and calcium (ADA, 1987, p. 1342~.
A virtually identical statement was released by the American Institute of
Nutrition jointly with the American Society for Clinical Nutrition (Callaway
et al., 1987~.
In its publication Standards for Obstetric-Gynecologic Services, the
American College of Obstetricians and Gynecologists (ACOG) included
the following statement:
Protein, iron, folio acid, and certain other vitamins and minerals are required
in greater amounts during pregnancy. If these needs are not met by increased
dietary intake, a vitamin/mineral supplement equal to the recommended dietary
allowances (RDA) for pregnant women should be given (ACOG, 1985, p. 20~.
In a separate publication the same year, the Disk Force on Adolescent
Pregnancy (1985) addressed nutritional needs of pregnant adolescents in
somewhat more detail, providing specific suggestions to consume protein-
rich foods with a goal of achieving a daily protein intake of 76 to 78 g.
Regarding iron, it stated: "Pregnancy requires 30-60 mg of iron per day.
Since dietary sources of iron are limited, and diet alone cannot supply
the needed iron, a supplement is recommended in appropriate amounts
to meet the increased need" Desk Force on Adolescent Pregnancy, 1985,
p. 28~. It also recommended a calcium intake of 1.2 to 1.6 g daily and
stated: "If the teen's normal diet includes large amounts of mink and
daily products, supplemental calcium will be unnecessary" Desk Force on
Adolescent Pregnancy, 1985, p. 29~. Further relevant recommendations
include the following: "During all pregnancies, a supplement of folio
acid not to exceed 1 mg per day is recommended" (p. 29) and "Because
certain vitamins may cause fetal malformations, general recommendations
for a vitamin supplement would be unwise" (p. 29~.
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INTRODUCT ON
239
The American Academy of Pediatrics (AAP) and ACOG jointly pub-
lished Guidelines for Perinatal Care (AAP/ACOG, 1988), which includes
slightly different recommendations: folio acid supplementation of at least
400 Friday and, for adolescents, calcium and phosphorus supplementation
or additional milk (more than 1 quart daily). With regard to other vitamins
and minerals:
The increased amounts of other vitamins and minerals recommended during
pregnancy . . . can usually be obtained through dietary intake, and the routine
use of a multivitamin supplement is not necessary. If there are doubts about
the adequacy of a patient's diet, however, a vitamin and mineral supplement
that provides the recommended dietary allowances can be given safely. It is
important to avoid excessive vitamin and mineral intakes (de, more than twice
the recommended dietary allowances) during pregnancy because both fat-soluble
and water-soluble vitamins may have toxic effects (AAP/ACOG, 1988, p. 196~.
The recommendations made by these professional groups were strongly
influenced by earlier FNB reports, including the 1980 (ninth) edition of
Recommended Dietary Allowances (NRC, 1980~. The recently published
tenth edition of the RDAs (NRC, 1989) includes a number of revised
recommendations for nutrient intake. For example, the 1989 RDA for
folate (often called folacin or folio acid) intake during pregnancy is 400
,ug, compared with 800 fig in 1980. The 1989 RDAs for pregnant women
appear in Table 11-1.
Directions on the labels of certain prenatal vitamin-mineral supple-
ments may lead to intakes well in excess of the 1989 RDAs. This is not
readily apparent to either the user or the physician issuing the prescrip-
tion, since label information is expressed in terms of the Food and Drug
Administration's U.S. Recommended Daily Allowances (U.S. RDA) not
the RDAs, which are substantially different for several nutrients (see Able
11-1~: 100% of the U.S. RDA may be more or less than the RDN The
safety of vitamin-mineral supplementation deserves close examination, as
does the possibility of benefit to mother or infant.
USAGE PATTERNS
Prenatal vitamin-mineral supplementation has been widespread in the
United States for many years. Approximately 92% of 7,825 married
mothers* in the 1980 National Natality Survey reported taking vitamin
supplements during pregnancy (K Keppel, National Center for Health
Statistics, personal communication, 1988), as did nearly 88% of the 116
* Unmarried women were not interviewed in the 1980 National Natality Survey. For more infor-
mation about the survey, see Chapter 5.
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240
DIETARY INTAKE AND NUTRIENT SUPP~FM:ENTS
TABLE 11-l Recommended Dietary Allowances (RDAs) and Estimated
Safe and Adequate Daily Dietary Intakes (ESADDIs) Compared with
U.S. Recommended Daily Allowances (U.S. RDAs) for Nonpregnant
and Pregnant Women
U.S. RDAb
RDA or ESADDI for Adults and Pregnant or
Pregnant Adult Children over Lactatin'
Nutrient Womena 3 Years OldC Women
RDA:
Protein60 g65 g65 g
Vitamin A800 mg REe5,000 IU8,000 IU
Vitamin D10 ,ugf400 IU400 IU
Vitamin E10 mg of a-TEg30 IU30 IU
Vitamin K65 ,ugh
Vitamin C70 mg60 mg60 mg
Thiamin1.5 mg1.5 mg1.7 mg
Riboflavin1.6 mg1.7 mg2.0 mg
Niacin17 mg NE'20 mg20 mg
Vitamin B62.2 mg2.0 mg2.5 mg
Folacin400 ,ug400 ,ug800 ~g
Vitamin B~22.2 ,ug6 ,ug8 ,ug
Calcium1,200 mg1,000 mg1,300 mg
Phosphorus1,200 mg1,000 mg1,300 mg
Magnesium3()0 mg400 mg450 mg
Iron30 mg18 mg18 mg
Zinc15 mg15 mg15 mg
Iodine175 ,ug150 ,ug150 ,ug
Selenium65,ug
ESADDI:
Biotin30-100 ,ug300 ,ug300 ,ug
Pantothenic acid4-7 mg10 mg10 mg
Copper1.5-3.0 mg2 mg2 mg
Manganese2.0-5.0 mg
Fluoride1.5-4.0 mg
Chromium50-200 ,ug
Molybdenum75-250,ug
a From NRC, 1989.
b From National Nutrition Consortium, 1975.
c Used in the labeling of most foods, e.g., ready-to-eat cereals, and vitamin and mineral
supplements for adults.
Used in the labeling of vitamin-mineral supplements designed for pregnant and lactating
women.
t 1 RE (retinol equivalent) = 1 ,ug of retinol, ~ ,ug ot ,~-carotene, or l~ ,ug OI Olner
provitamin A carotenoids; whereas 1 IU is usually equated to 0.3 ,ug of retinol and to 0.6
,ug of ,B-carotene. By calculation, 8,000 IU of vitamin A from vitamin supplements or cereal
fortified with retinol equals 2,400 RE.
f 1 ,ug of vitamin D (cholecalciferol) = 40 IU.
g 1 a-TE (tocopherol equivalent) = 1 mg of RRR-a-tocopherol = 1.49 IU RRR-a
tocopherol = 0.74 IU of all-rac-a-tocopherol (the synthetic form).
h = Not established.
i 1 NE (niacin equivalent) is equal to 1 mg of niacin or 60 mg of dietary tryptophan.
OCR for page 241
INTRODUCTION
241
pregnant women in the U.S. Department of Agriculture's (USDAs) Con-
tinuing Survey of Food Intake by Individuals (S. Krebs-Smith, Food and
Nutrition Service, personal communication, 1988~.
Vitamin-mineral supplementation early in pregnancy, before prenatal
care, may be of particular interest because of associations (both positive and
negative) between supplement use and teratogenesis. Although supplement
usage rates by women in the first few weeks of gestation have not been
reported, they may parallel those reported for nonpregnant, nonlactating
women in the childbearing years, which vary substantially by ethnic back-
ground, education, and income (Block et al., 1988; Koplan et al., 1986~.
The less advantaged groups have lower supplement usage rates. For exam-
ple, 55% of all women in their childbearing years reported taking a vitamin
or mineral supplement regularly or occasionally (USDA, 1987b) compared
with 48% of low-income women who were not participating in the Food
Stamp Program and 39% of those who were (USDA, 1987a). Analysis
of data collected in the first (1971-1975) National Health and Nutrition
Examination Survey indicates that among females between 25 and 34 years
of age, 26.4% of the whites and 15.5% of the blacks reported regular use
of vitamin and mineral supplements (Block et al., 1988~.
SCOPE OF REPORT
The Subcommittee on Dietary Intake and Nutnent Supplements Dur-
ing Pregnancy was asked to review recent studies of dietary intake, sup-
plement usage, laboratory indices reflecting nutrient intake, and nutrient
requirements as a basis for developing conclusions and recommendations
pertaining to the use of nutrient supplements during pregnancy. The spon-
sor, the Bureau of Maternal and Child Health and Resources Development
of the U.S. Department of Health and Human Services, also asked the
subcommittee to give special attention to calcium, iron, zinc, folate, and
protein most of which have been the subject of an increasing amount of
research because of their suspected influence on the short- and long-term
health status of mothers or their infants.
The subcommittee considered the following questions as they pertain
to pregnancy:
· For which nutrients is it reasonable to expect that food alone will
provide adequate intake?
· For which nutrients, if any, is supplementary intake from pharma-
ceutical preparations desirable?
· If supplementation is recommended or practiced, what level is
appropriate?
· Is there danger of toxicity from use of any nutrient supplements?
OCR for page 242
242
DIETARY INTAKE AND NUTRIENT SUPPLEMENTS
Do interactions among nutrients and between drugs and nutrients
substantially change the pregnant woman's ability to achieve satisfactory
nutritional status?
· Should recommendations differ for adolescents, for women aged
35 and over, and for women of different ethnic backgrounds?
These are questions faced by pregnant women as well as by the practitioners
and the health and nutrition programs that serve them.
New findings relative to nutrient-nutrient interactions may be relevant
in providing nutritional advice to pregnant women, both from the stand-
point of desirable types of food combinations and when considering the
use of supplemental nutrients. In addition, the subcommittee considered
the use of such substances as street drugs, alcohol, and tobacco, which
may have far-reaching consequences on the developing fetus and the fam-
ily unit. It recognized the need to determine the nutritional implications
of different forms of substance abuse and to develop realistic approaches
to modifying food intake, recommending supplement use, or delivering
nutrition services without losing sight of the importance of taking steps
to modify the harmful practice. The subcommittee also searched for ev-
idence relating differences in body size, genetic makeup, age, recent life
circumstances (e.g., living in a refugee settlement), and customary eating
practices to the need for supplementation. However, the lack of scientific
data limited the extent to which the subcommittee was able to address
these issues.
UNDERLYING ASSUMPTIONS
During the course of its deliberations, the subcommittee agreed that
the following concepts were important in guiding its work:
· Supplementation is justified only when there is evidence that dietary
intake of the nutrient is likely to be sufficiently low to produce adverse
effects on maternal or fetal health or on pregnancy outcomes.
· Laboratory indices of nutrient deficiencies developed for nonpreg-
nant women are frequently inappropriate for women who are pregnant.
Standards for pregnant women are often unavailable. This is an additional
reason why optimal maternal and fetal health should be a major criterion
on which to judge the need for supplementation.
· Supplementation is an intervention, for which both safety and
efficacy are of concern.
It is important to review the effects of nutrient supplements during
organogenesis, which occurs very early in pregnancy.
· The practical issue of the patient's willingness to take supplements
must be considered when making recommendations for supplementation.
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INTRODUCTION
243
ORGANIZATION OF THE REPORT
Chapter 12 presents useful background information pertaining to the
assessment of prenatal nutrient needs. Chapter 13 presents an analysis of
evidence about the dietary intake of pregnant women. These two chap-
ters provide a framework for the next six chapters (Chapters 14 through
19), which address specific nutrients of possible concern during pregnancy.
In Chapter 20, the subcommittee presents data on interactions among
food, nutrients, and certain nonnutritive substances (e.g., cigarettes, coffee
or caffeine, alcohol, marijuana, and cocaine) used during pregnancy and
examines how these interactions may influence recommendations for sup-
plementation. Periconceptional nutrition and the evidence for and against
the use of multivitamins in the prevention of neural tube defects are d~s-
cussed In Chapter 21. Chapter 1 contains the subcommittee's conclusions
and recommendations.
REFERENCES
AAP/ACOG (American Academy of Pediatrics/American College of Obstetricians and
Gynecologists). 1988. Guidelines for Perinatal Care, 2nd ed. American Academy of
Pediatrics, Elk Grove, Ill. 356 pp.
ACOG (American College of Obstetricians and Gynecologists). 1985. Standards for
Obstetric-Gynecologic Services, 6th ed. The American College of Obstetricians and
Gynecologists, Washington, D.C. 109 pp.
ADA (American Dietetic Association). 1987. Recommendations concerning supplement
usage: ADA statement. J. Am. Diet. Assoc. 87:1342-1343.
Block, G., C. Cox, J. Madans, G.B. Schreiber, L. Licitra, and N. Melia. 1988. Vitamin
supplement use, lay demographic characteristics. Am. J. Epidemiol. 127:297-309.
Callaway, C.W., KW. McNutt, R.S. Rivlin, A.C. Ross, H.H. Sanstead, and A.P. Simopoulos.
1987. Statement on vitamin and mineral supplements. J. Nutr. 117:1649.
Koplan, J.P., J.L. Annest, P.M. Layde, and G.L Rubin. 1986. Nutrient intake and
supplementation in the United States (NHANES II). Am. J. Public Health 76:287-289.
National Nutrition Consortium. 1975. Nutrition Labeling: How it Can Work for You.
National Nutrition Consortium, Bethesda, Md. 134 pp.
NRC (National Research Council). 1970. Maternal Nutrition and the Course of Pregnancy.
Report of the Committee on Maternal Nutrition, Food and Nutrition Board. National
Academy of Sciences, Washington, D.C. 241 pp.
NRC (National Research Council). 1978. Laboratory Indices of Nutritional Status in
Pregnancy. Report of the Committee on Nutrition of the Mother and Preschool
Child, Food and Nutrition Board. National Academy of Sciences, Washington, D.C.
195 pp.
NRC (National Research Council). 1980. Recommended Dietary Allowances, 9th ed. Report
of the Committee on Dietary Allowances, Food and Nutrition Board, Division of
Biological Sciences, Assembly of Life Sciences. National Academy Press, Washington,
D.C. 185 pp.
NRC (National Research Council). 1981. Nutrition Services in Perinatal Care. Report of
the Committee on Nutrition of the Mother and Preschool Child, Food and Nutrition
Board, Assembly of Life Sciences. National Academy Press, Washington, D.C. 72 pp.
NRC (National Research Council). 1982. Alternative Dietary Practices and Nutritional
Abuses in Pregnancy: Proceedings of a Workshop. Report of the Committee on
Nutrition of the Mother and Preschool Child, Food and Nutrition Board, Commission
on Life Sciences. National Academy Press, Washington, D.C. 211 pp.
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244
D ETARY INTAKE AND NUTRIENT SUPPLEMENTS
NRC (National Research Council). 1989. Recommended Dietary Allowances, 10th ed.
Report of the Subcommittee on the Tenth Edition of the RDAs, Food and Nutrition
Board, Commission on Life Sciences. National Academy Press, Washington, D.C. 284
PP
Ask Force on Adolescent Pregnancy. 1985. Adolescent Perinatal Health: A Guidebook
for Services. The American College of Obstetricians and Gynecologists, Washington,
D.C. 40 pp.
USDA (U.S. Department of Agriculture). 1987a. Nationwide Food Consumption Survey.
Continuing Survey of Food Intakes By Individuals. Low-Income Women 19-50 Years
and Their Children 1-5 Years, 1 Day, 1986. Report No. 86-2. Nutrition Monitoring
Division, Human Nutrition Information Service, U.S. Department of Agriculture,
Hyattsville, Md. 166 pp.
USDA (U.S. Department of Agriculture). 1987b. Nationwide Food Consumption Survey.
Continuing Survey of Food Intakes by Individuals. Women 19-50 Years and Their
Children 1-5 Yeam, 1 Day, 1986. Report No. 86-1. Nutrition Monitoring Division,
Human Nutrition Information Service, U.S. Department of Agriculture, Hyattsville,
Md. 98 pp.
Representative terms from entire chapter:
dietary intake
