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Institute of Medicine (US) and National Research Council (US) Committee to Reexamine IOM Pregnancy Weight Guidelines; Rasmussen KM, Yaktine AL, editors. Weight Gain During Pregnancy: Reexamining the Guidelines. Washington (DC): National Academies Press (US); 2009.

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Weight Gain During Pregnancy: Reexamining the Guidelines.

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BSupplementary Information on Nutritional Intake

DIETARY REFERENCE INTAKES FOR PREGNANCY

TABLE B-1AEquations to Estimate Energy Requirement for Pregnant Women by Trimester

Estimated Energy Requirement (kcal/day) = Nonpregnant EER + Pregnancy Energy Deposition
1st trimesterEER = Nonpregnant (adolescent or adult) EER + 0
2nd trimesterEER = Nonpregnant (adolescent or adult) EER + 340
3rd trimesterEER = Nonpregnant (adolescent or adult) EER + 452

NOTE: EER = Estimated Energy Requirement. Use equations in Table B-1B to calculate non-pregnant EER. EER for adult women should be used for ages 19–50 years; EER for adolescent girls should be used for ages 9–18 years

SOURCE: IOM, 2006.

TABLE B-1BEquations to Calculate Estimated Energy Requirement (EER) for Nonpregnant Adolescents or Adult Women

1418 years of Age
Estimated Energy Requirement (kcal/day) = Total Energy Expenditure + Energy Deposition
EER = 135.3 − (30.8 × age [y]) + PA × [(10.0 × weight [kg]) + (934 × height [m])] + 25
19 Years and Older
Estimated Energy Requirement (kcal/day) = Total Energy Expenditure
EER = 354 − (6.91 × age [y]) + PA × [(9.36 × weight [kg]) + (726 v height [m])]

NOTE: PA = Physical Activity Coefficient. Use equations in Table B-1C to calculate PA.

SOURCE: IOM, 2006.

TABLE B-1CPhysical Activity Coefficients (PA values) for Use in EER Equations for Adolescents or Adult Women

Sedentarya (PAL 1.0–1.39)Low Activeb (PAL 1.4–1.59)Activec (PAL 1.6–1.89)Very Actived (PAL 1.9–2.5)
14–18 years of Age1.01.161.311.56
19 Years and Older1.01.121.271.45

NOTE: PAL = Physical Activity Level.

a

E.g., typical daily living activities (e.g., household tasks, walking to the bus).

b

E.g., typical daily living activities PLUS 30–60 minutes of daily moderate activity (e.g., walking at 5–7 km/h).

c

E.g., typical daily living activities PLUS at least 60 minutes of daily moderate activity.

d

E.g., typical daily living activities PLUS at least 60 minutes of daily moderate activity PLUS an additional 60 minutes of vigorous activity or 120 minutes of moderate activity.

SOURCE: IOM, 2006.

TABLE B-2Dietary Reference Intakes for Pregnant Women: Vitamins, Elements, Total Water, and Macronutrients in Alphabetical Order

NutrientEARaRDAb/AIcULd
Biotin
 14–18 y30 μg/day
 19–30 y30 μg/day
 31–50 y30 μg/day
Boron
 14–18 y17 mg/day
 19–30 y20 mg/day
 31–50 y20 mg/day
Calcium
 14–18 y1,300 mg/day2.5 g/day
 19–30 y1,000 mg/day2.5 g/day
 31–50 y1,000 mg/day2.5 g/day
Carbohydrate
 14–18 y135 g/day175 g/day
 19–30 y135 g/day175 g/day
 31–50 y135 g/day175 g/day
Chloride
 14–18 y2.3 g/day3.6 g/day
 19–30 y2.3 g/day3.6 g/day
 31–50 y2.3 g/day3.6 g/day
Choline
 14–18 y450 mg/day3.0 g/day
 19–30 y450 mg/day3.5 g/day
 31–50 y450 mg/day3.5 g/day
Chromium
 14–18 y29 μg/day
 19–30 y30 μg/day
 31–50 y30 μg/day
Copper
 14–18 y785 μg/day1,000 μg/day8,000 μg/day
 19–30 y800 μg/day1,000 μg/day10,000 μg/day
 31–50 y800 μg/day1,000 μg/day10,000 μg/day
Fiber (Total)
 14–18 y28 g/day
 19–30 y28 g/day
 31–50 y28 g/day
Flouride
 14–18 y3.0 mg/day10 mg/day
 19–30 y3.0 mg/day10 mg/day
 31–50 y3.0 mg/day10 mg/day
Folatee
 14–18 y520 μg/day600 μg/day800 μg/day
 19–30 y520 μg/day600 μg/day1,000 μg/day
 31–50 y520 μg/day600 μg/day1,000 μg/day
Iodine
 14–18 y160 μg/day220 μg/day900 μg/day
 19–30 y160 μg/day220 μg/day1,100 μg/day
 31–50 y160 μg/day220 μg/day1,100 μg/day
Iron
 14–18 y23 mg/day27 mg/day45 mg/day
 19–30 y22 mg/day27 mg/day45 mg/day
 31–50 y22 mg/day27 mg/day45 mg/day
Linoleic acid
 14–18 y13 g/day
 19–30 y13 g/day
 31–50 y13 g/day
α-Linolenic Acid
 14–18 y1.4 g/day
 19–30 y1.4 g/day
 31–50 y1.4 g/day
Magnesiumf
 14–18 y335 mg/day400 mg/day350 mg/day
 19–30 y290 mg/day350 mg/day350 mg/day
 31–50 y300 mg/day360 mg/day350 mg/day
Manganese
 14–18 y2.0 mg/day9 mg/day
 19–30 y2.0 mg/day11 mg/day
 31–50 y2.0 mg/day11 mg/day
Molybdenum
 14–18 y40 μg/day50 μg/day1,700 μg/day
 19–30 y40 μg/day50 μg/day2,000 μg/day
 31–50 y40 μg/day50 μg/day2,000 ug/day
Niacing
 14–18 y14 mg/day18 mg/day30 mg/day
 19–30 y14 mg/day18 mg/day35 mg/day
 31–50 y14 mg/day18 mg/day35 mg/day
Nickel
 14–18 y1.0 mg/day
 19–30 y1.0 mg/day
 31–50 y1.0 mg/day
Pantothenic Acid
 14–18 y6.0 mg/day
 19–30 y6.0 mg/day
 31–50 y6.0 mg/day
Phosphorus
 14–18 y1,055 mg/day1,250 mg/day3.5 g/day
 19–30 y580 mg/day700 mg/day3.5 g/day
 31–50 y580 mg/day700 mg/day3.5 g/day
Potassium
 14–18 y4.7 g/day
 19–30 y4.7 g/day
 31–50 y4.7 g/day
Proteinh
 14–18 y0.88 g/kg/day71 g/day
 19–30 y0.88 g/kg/day71 g/day
 31–50 y0.88 g/kg/day71 g/day
Riboflavin
 14–18 y1.2 mg/day1.4 mg/day
 19–30 y1.2 mg/day1.4 mg/day
 31–50 y1.2 mg/day1.4 mg/day
Selenium
 14–18 y49 μg/day60 μg/day400 μg/day
 19–30 y49 μg/day60 μg/day400 μg/day
 31–50 y49 μg/day60 μg/day400 μg/day
Sodium
 14–18 y1.5 g/day2.3 g/day
 19–30 y1.5 g/day2.3 g/day
 31–50 y1.5 g/day2.3 g/day
Thiamin
 14–18 y1.2 mg/day1.4 mg/day
 19–30 y1.2 mg/day1.4 mg/day
 31–50 y1.2 mg/day1.4 mg/day
Vitamin Ai
 14–18 y530 μg RAE/day750 μg RAE/day2,800 μg/day
 19–30 y550 μg RAE/day770 μg RAE/day3,000 μg/day
 31–50 y550 μg RAE/day770 μg RAE/day3,000 μg/day
Vitamin B6
 14–18 y1.6 mg/day1.9 mg/day80 mg/day
 19–30 y1.6 mg/day1.9 mg/day100 mg/day
 31–50 y1.6 mg/day1.9 mg/day100 mg/day
Vitamin B12
 14–18 y2.2 μg/day2.6 μg/day
 19–30 y2.2 μg/day2.6 μg/day
 31–50 y2.2 μg/day2.6 μg/day
Vitamin C
 14–18 y66 mg/day80 mg/day1,800 mg/day
 19–30 y70 mg/day85 mg/day2,000 mg/day
 31–50 y70 mg/day85 mg/day2,000 mg/day
Vitamin D
 14–18 y5.0 μg/dayj50 μg/day
 19–30 y5.0 μg/dayj50 μg/day
 31–50 y5.0 μg/dayj50 μg/day
Vitamin Ek
 14–18 y12 mg/day15 mg/day8,00 mg/day
 19–30 y12 mg/day15 mg/day1,000 mg/day
 31–50 y12 mg/day15 mg/day1,000 mg/day
Vitamin K
 14–18 y75 μg/day
 19–30 y90 μg/day
 31–50 y90 μg/day
Water (Total)l
 14–18 y3.0 L/day
 19–30 y3.0 L/day
 31–50 y3.0 L/day
Zinc
 14–18 y10.5 mg/day12 mg/day34 mg/day
 19–30 y9.5 mg/day11 mg/day40 mg/day
 31–50 y9.5 mg/day11 mg/day40 mg/day

NOTE: This table (taken from the DRI reports; see www.nap.edu) presents Recommended Dietary Allowances (RDA) in bold type or Adequate Intakes (AI) in ordinary type in Column 3.

a

EAR = Estimated Average Requirement. An EAR is the average daily nutrient intake level estimated to meet the requirements of half of the healthy individuals in a group.

b

RDA = Recommended Dietary Allowance. An RDA is the average daily dietary intake level sufficient to meet the nutrient requirements of nearly all (97–98 percent) healthy individuals in a group. It is calculated from an EAR.

c

AI = Adequate Intake. If sufficient scientific evidence is not available to establish an EAR, and thus calculate and RDA, an AI is usually developed. The AI for breast-fed infants is the mean intake. The AI for other life-stage groups and gender groups (except healthy breast-fed infants) is believed to cover the needs of all healthy individuals in the group, but a lack of data or uncertainty in the data prevents being able to specify with confidence the percentage of individuals covered by this intake. In the absence of a UL, extra caution may be warranted in consuming levels above recommended intakes. Members of the general population should be advised not to routinely exceed the UL. The UL is not meant to apply to individuals who are treated with the nutrient under medical supervision or to individuals with predisposing conditions that modify their sensitivity to the nutrient

d

UL = Tolerable Upper Intake Level. The UL is the highest level of daily nutrient intake that is likely to pose no risk of adverse health effects to almost all individual in the general population. Unless otherwise specified, the UL represents total intake from food, water, and supplements.

e

As dietary folate equivalents (DFEs). 1 DFE = 1 μg food folate = 0.6 μg of folic acid from fortified food or as a supplement consumed with food = 0.5 μg of folic acid from a supplement taken on an empty stomach. In view of evidence linking folate intake with neural tube defects in the fetus, it is recommended that all women capable of becoming pregnancy consume 400 μg from supplements or fortified foods in addition to intake of food folate from a varied diet. It is assumed that women will continue consuming 400 μg from supplements or fortified food until their pregnancy is confirmed and they enter prenatal care, which ordinarily occurs after the end of the periconceptional period—the critical time for formation of the neural tube. The UL for folate applies to synthetic forms obtained from supplements, fortified foods, or a combination of the two.

f

The ULs for magnesium represent intake from pharmacological agents only and do not include intake from food and water.

g

For EAR and RDA: as niacin equivalents (NE). 1 mg of niacin = 60 mg of tryptophan. The UL for niacin applies to synthetic forms obtained from supplements, fortified foods, or a combination of the two.

h

Based on g protein per kg of body weight for the reference body weight, e.g., for adults 0.8 g/kg body weight for the reference body weight.

i

RAE = Retinol activity equivalent. 1 μg RAE = 1 μg retinol, 12 μg β-carotene, and 24 μg α-carotene or β-cryptoxanthin. The RAE for dietary provitamin A carotenoids in foods is twofold greater than retinol equivalents (RE), whereas the RAE for preformed vitamin A in foods is the same as RE. The UL for vitamin A is for preformed vitamin A only.

j

In the absence of adequate exposure to sunlight, and as cholecalciferol. 1 μg cholecalciferol = 40 IU vitamin D.

k

As α-tocopherol. For EAR and RDA: α-tocopherol includes RRR-α-tocopherol, the only form of α-tocopherol that occurs naturally in foods, and the 2R-stereoisomeric forms of α-tocopherol (RRR-, RSR-, RRS-, and RSS-α-tocopherol) that occur in fortified foods and supplements. This does not include the 2S-stereoisomeric forms of α-tocopherol (SRR-, SSR-, SRS-, and SSS-α-tocopherol), also found in fortified foods and supplements. The 2S-stereoisomers are not stored in the body. For UL: applies to any form of supplemental α-tocopherol.

l

Total water includes all water contained in food, beverages, and drinking water.

SOURCE: IOM, 2006.

TABLE B-3Acceptable Macronutrient Distribution Ranges

MacronutrientRange (percent of energy)
4–18 yAdults
Fat25–3520–35
n-6 Polyunsaturated fatty acids* (linoleic acid)5–105–10
n-3 Polyunsaturated fatty acids* (α-linolenic acid)0.6–1.20.6–1.2
Carbohydrate46–6546–65
Protein10–3010–35
*

Approximately 10 percent of the total can come from longer-chain n-3 or n-6 fatty acids.

SOURCE: IOM, 2006.

TABLE B-4Additional Macronutrient Recommendations

MacronutrientRecommendation
Dietary cholesterolAs low as possible while consuming a nutritionally adequate diet
Trans fatty acidsAs low as possible while consuming a nutritionally adequate diet
Saturated fatty acidsAs low as possible while consuming a nutritionally adequate diet
Added sugars*Limit to no more than 25% of total energy
*

Not a recommended intake. A daily intake of added sugars that individuals should aim for to achieve a healthful diet was not set.

SOURCE: IOM, 2006.

TRENDS IN ENERGY INTAKE AND MARKERS OF ENERGY DENSITY

As the prevalence of obesity rises among childbearing-aged women and women entering pregnancy, important shifts in diet and physical activity have also occurred. In a recent study, Nielsen and colleagues (2002) used nationally representative data from the 1977–1978 Nationwide Food Consumption Survey and the 1989–1991 and 1994–1996 Continuing Surveys of Food Intake by Individuals to investigate the trends in total energy intake and energy intake by meal pattern type (Figure B-1). Data were stratified by age but not sex. These investigators found that among U.S. adults aged 19–39 years, there was an 18 percent increase in total energy intake over the 20-year period (1856 to 2198 kcal/d). When separated into energy from meal pattern type, the major contributor to this overall increase in energy intake was a sharp 58 percent increase in energy from snacks (244–387 kcal/d). Additionally, the percent of total energy from key food groups, such as salty snacks, sweetened beverages, candy, pizza, French fries, cheeseburgers, and Mexican-style food, increased between survey years 1977–1978 and 1994–1996.

FIGURE B-1. Trends in energy intake and meal pattern type, U.S. adults aged 19–39 years.

FIGURE B-1

Trends in energy intake and meal pattern type, U.S. adults aged 19–39 years. SOURCE: Nielsen et al., 2002.

These authors further investigated trends in beverage intake using the aforementioned data sources plus the 1999–2001 nationally-representative NHANES. For all age groups, including adults aged 19 to 39 years, sweetened beverage intake increased and milk consumption decreased between survey years 1977–1978 and 1999–2001 (Figure B-2) (Nielsen and Popkin, 2004). Specifically, energy from soft drinks nearly tripled (2.8 to 7.0 percent [approximately 50 to 144 kcal per person per day]), energy from fruit drinks doubled (1.1 to 2.2 percent [from 20 to 45 kcal per person per day]), and energy from milk decreased (8.0 to 5.0 percent [from 143 to 99 kcal per person per day]).

FIGURE B-2. Trends in U.S. beverage consumption 1977–2001: percent of total energy intake.

FIGURE B-2

Trends in U.S. beverage consumption 1977–2001: percent of total energy intake. SOURCE: Nielsen and Popkin, 2004.

Taken together, these findings illustrate an increase in consumption of foods of low nutrient density in the general population. This has special implications for pregnancy and lactation, which require modest increases in energy intake but proportionally greater increases in vitamin and mineral intake.

The U.S. Dietary Guidelines represent federal nutrition policy. The recommendations of the Dietary Guidelines are interpreted for use by healthy Americans over 2 years of age in MyPyramid (available online: http://www. MyPyramid.gov [accessed October 16, 2008]). The current MyPyramid recommends that females aged 14–18 years and 31–50 years consume 8 combined servings of fruits and vegetables, while 9 combined servings is recommended for females aged 19–30 years. MyPyramid also makes more specific recommendations about types of vegetables, including dark green and orange vegetables, and legumes to ensure consumption of the variety of nutrients available from these foods. When the Guenther et al. (2006) examined sub-groups of vegetables, mean intakes for childbearing-aged women were below the recommended amounts for all subgroups except for starchy vegetables (Figure B-3). These data clearly illustrate that childbearing-aged women failed to meet recommendations for fruits and vegetables.

FIGURE B-3. Mean daily intakes of vegetables by subtype among U.S. females 19–30 years of age.

FIGURE B-3

Mean daily intakes of vegetables by subtype among U.S. females 19–30 years of age. SOURCE: Guenther et al., 2006.

Another method of quantifying the overall quality of American’s diets is through the use of the Healthy Eating Index-2005 (HEI-2005), a tool designed to measure compliance of diets with the key, diet-related recommendations of the 2005 Dietary Guidelines for Americans (HHS/USDA, 2005). The HEI-2005 has 12 components, as seen in Table B-5 (Guenther et al., 2006). For most components, higher intakes result in higher scores. Note, however, that for three components, saturated fat, sodium, and calories from solid fats, alcoholic beverages, and added sugars (SoFAAS), lower intake levels result in higher scores because lower intakes are more desirable. Monitoring changes in the HEI-2005 scores can provide a method for nutrition surveillance in the population.

TABLE B-5. Estimated Healthy Eating Index-2005 Component and Total Scores, United States (1994–1996 and 2001–2002).

TABLE B-5

Estimated Healthy Eating Index-2005 Component and Total Scores, United States (1994–1996 and 2001–2002).

In a recent analysis, trends in the HEI-2005 scores and its components were published for all Americans two years of age and older (subgroups of the population were not studied). From 1994–1996 to 2001–2002, there was little change in either overall HEI-2005 score or its components. The average HEI-2005 score was 58.2 out of 100 possible points in both time periods. American’s diets consistently met recommendations for the groups “Total Grains” and “Meat and Beans,” but were far below the maximum score for the groups, “Dark Green and Orange Vegetables” and “Legumes” as well as whole grains. Intakes from SoFAAS were well below the recommendations, as reflected in low scores on these components. From 1994–1996 to 2001–2002 the HEI-2005 score declined for the groups “Whole Fruit,” “Total Vegetables,” and “Whole Grains” while the score for the groups “Milk,” “Oils,” and “Sodium” improved.

Some of these dietary pattern changes may be a result of the trend toward obtaining a greater proportion of food outside the home. Self-reported dietary data from national surveys was used to show that the percentage of total energy intake obtained from foods consumed at home decreased from 77 in 1977–1978 to 65 percent from 1994–1996 (Figure B-4) (Nielsen et al., 2002). The amount of energy obtained from foods consumed from restaurants, including fast food establishments, doubled from 9 to 21 percent during this same period.

FIGURE B-4. Trends in energy intake (percent energy) by location, Americans aged 2+ years.

FIGURE B-4

Trends in energy intake (percent energy) by location, Americans aged 2+ years. SOURCE: Nielsen et al., 2002.

The aforementioned analysis relied on dietary intake data obtained from surveys. There is no “gold standard” method of assessing dietary intakes in individuals, and all self-reported dietary intake data have inherent biases. Therefore food supply data, collected directly from food producers and distributors, are often used to examine trends in American dietary patterns. The estimates are adjusted for spoilage, cooking losses, plate waste, and other food losses accumulated throughout the marketing system and the home. Analysis of trends in food supply data provide the same conclusions regarding trends in increasing energy intake and overall diet quality of Americans as self-reported survey data.

The most recent loss-adjusted annual per capita food supply data analyses by the USDA’s Economic Research Service suggests a 12 percent increase in total energy intake (~300 kcal per person per day) from 1985 to 2000 (USDA, 2002; available online: http://www.ers.usda.gov/publications/FoodReview/DEC2002/frvol25i3a.pdf [accessed April 16, 2009]) (Figure B-5). Of the 300-kcal increase, grains (mainly refined grains) accounted for 46 percent; added fats, 24 percent; added sugars, 23 percent; fruits and vegetables, 8 percent of the increase. At the same time, energy intake from the meat and dairy groups together declined by 1 percent. When the per capita food supply data in 2000 was compared with the 1992 Food Guide Pyramid recommendations as a marker of overall diet quality, intakes exceeded recommendations for grains, meats, added fats, and added sugars, and fell below recommendations for dairy, fruits, and non-starchy vegetables (USDA, 2002; available online: http://www.ers.usda.gov/publications/FoodReview/DEC2002/frvol25i3a.pdf [accessed April 16, 2009]).

FIGURE B-5. Energy from the U.S. per capita food supply (adjusted for losses).

FIGURE B-5

Energy from the U.S. per capita food supply (adjusted for losses). 1Rounded to the nearest hundred. 2Not calculated for years beyond 1970.

REFERENCES

  1. Guenther PM, Dodd KW, Reedy J, Krebs-Smith SM. Most Americans eat much less than recommended amounts of fruits and vegetables. Journal of the American Dietetic Association. 2006;106(9):1371–1379. [PubMed: 16963342]
  2. HHS/USDA (U.S. Department of Health and Human Services/United States Department of Agriculture). Dietary Guidelines for Americans, 2005. 6th Edition. Washington, DC: Government Printing Office; 2005.
  3. IOM (Institute of Medicine). Dietary Reference Intakes: The Essential Guide to Nutrient Requirement. Washington, DC: The National Academies Press; 2006.
  4. Nielsen SJ, Popkin BM. Changes in beverage intake between 1977 and 2001. American Journal of Preventive Medicine. 2004;27(3):205–210. [PubMed: 15450632]
  5. Nielsen SJ, Siega-Riz AM, Popkin BM. Trends in energy intake in U.S. between 1977 and 1996: similar shifts seen across age groups. Obesity Research. 2002;10(5):370–378. [PubMed: 12006636]
Copyright © 2009, National Academy of Sciences.
Bookshelf ID: NBK32812

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