Appendix C
Systematic Review Matrix Summary1
The committee’s approach to task 2 was to determine whether the body of evidence used to develop the DGA included those studies with diet-related metabolic disease and were the most current and rigorous scientific studies available. Although evidence from existing (not updated) systematic reviews is used to develop the DGA (see Table C-5), the committee elected to focus on the new and updated systematic reviews. The systematic review matrix summary was thus created based on those new and updated reviews.
___________________
1 This appendix contains summarized information from the individual systematic reviews that were either new or updated for the 2020–2025 DGA. Further information can be found in the individual systematic reviews on the NESR website. In addition, Table C-5 has been added to capture the full spectrum of data used to create the 2020–2025 DGA and to clarify which components (new or updated systematic reviews) were focused on by this committee. This clarifying footnote has been added since the release of a prepublication version of the report to the sponsor.
Systematic Review | Strength of Evidence Grade by Age Group, Life Stage, or Subtopic |
---|---|
Dietary Patterns | |
Dietary Patterns and Growth, Size, Body Composition, and/or Risk of Overweight or Obesity |
|
Dietary Patterns and Risk of Cardiovascular Disease |
|
Dietary Patterns and Risk of Type 2 Diabetes |
|
Dietary Patterns and Breast, Colorectal, Lung, and Prostate Cancer |
|
Dietary Patterns and Bone Health |
|
Dietary Patterns and Neurocognitive Health |
|
Dietary Patterns and Sarcopenia |
|
Dietary Patterns and All-Cause Mortality |
|
Pregnancy and Lactation | |
Dietary Patterns During Pregnancy and Gestational Weight Gain | Grade: Limited |
Systematic Review | Strength of Evidence Grade by Age Group, Life Stage, or Subtopic |
---|---|
Dietary Patterns During Lactation and Postpartum Weight Loss | Grade Not Assignable (insufficient evidence) |
Dietary Patterns During Lactation and Human Milk Composition and Quantity |
|
Dietary Patterns During Lactation and Developmental Milestones, Including Neurocognitive Development, in the Child | Grade Not Assignable (no evidence) |
Folic Acid from Fortified Foods and/or Supplements During Pregnancy and Lactation and Health Outcomes |
|
Omega-3 Fatty Acids from Supplements Consumed Before and During Pregnancy and Lactation and Developmental Milestones, Including Neurocognitive Development, in the Child |
|
Systematic Review | Strength of Evidence Grade by Age Group, Life Stage, or Subtopic |
---|---|
Maternal Diet During Pregnancy and Lactation and Risk of Child Food Allergies and Atopic Allergic Diseases |
|
Birth to 24 Months | |
The Duration, Frequency, and Volume of Exclusive Human Milk and/or Infant Formula Consumption and Overweight and Obesity |
|
The Duration, Frequency, and Volume of Exclusive Human Milk and/or Infant Formula Consumption and Nutrient Status |
|
Iron from Supplements Consumed During Infancy and Toddlerhood and Growth, Size, and Body Composition | Grades: Moderate, Not Assignable (insufficient and no evidence) |
Vitamin D from Supplements Consumed During Infancy and Toddlerhood and Bone Health | Grades: Limited, Not Assignable (insufficient evidence) |
Systematic Review | Strength of Evidence Grade by Age Group, Life Stage, or Subtopic |
---|---|
Beverages and Added Sugars | |
Beverage Consumption and Growth, Size, Body Composition, and Risk of Overweight and Obesity |
|
Beverage Consumption During Pregnancy and Birth Weight | Grade Not Assignable (insufficient evidence) |
Alcohol Consumption and All-Cause Mortality |
|
Added Sugars Consumption and Risk of Cardiovascular Disease | Grades: Limited, Not Assignable (insufficient evidence) |
Dietary Fats and Seafood | |
Types of Dietary Fat and Cardiovascular Disease |
|
Seafood Consumption During Pregnancy and Lactation and Neurocognitive Development in the Child |
|
Seafood Consumption during Childhood and Adolescence and Neurocognitive Development | Grade Not Assignable (insufficient and no evidence) |
Systematic Review | Strength of Evidence Grade by Age Group, Life Stage, or Subtopic |
---|---|
Seafood Consumption during Childhood and Adolescence and Cardiovascular Disease | Grade Not Assignable (insufficient evidence) |
Frequency of Eating | |
Frequency of Eating and Growth, Size, Body Composition, and Risk of Overweight and Obesity | Grade Not Assignable (insufficient evidence) |
Frequency of Eating and Cardiovascular Disease | Grade Not Assignable (insufficient evidence) |
Frequency of Eating and Type 2 Diabetes | Grade Not Assignable (insufficient evidence) |
Frequency of Eating During Lactation and Postpartum Weight Loss | Grade Not Assignable (insufficient evidence) |
Frequency of Eating During Pregnancy and Gestational Weight Gain | Grade Not Assignable (no evidence) |
Frequency of Eating and All-Cause Mortality | Grade Not Assignable (no evidence) |
a The 2020 DGAC committee determined that the conclusion drawn by the 2015 Dietary Guidelines Advisory Committee generally reflects the current state of science and carried forward the conclusion from the 2015 committee.
TABLE C-2 Summary of Included and Excluded Study Participants in the New and Updated Systematic Reviews for the 2020–2025 Dietary Guidelines for Americans, by Age or Life Stage*
Systematic Review | Age or Life Stage of Study Participants at Intervention or Exposure and Outcomea,b | |||||
---|---|---|---|---|---|---|
Infants (birth to 24 months) | Children (2–18 years) | Adults (19–64 years) | Older Adults (65 years and older) | Women During Pregnancy | Women During Lactation | |
Dietary Patterns | ||||||
Dietary Patterns and Growth, Size, Body Composition, and/or Risk of Overweight or Obesity | Exclude | Include | Include | Include | Include | Include |
Dietary Patterns and Risk of Cardiovascular Disease | Exclude | Include | Include | Include | Include | Include |
Dietary Patterns and Risk of Type 2 Diabetes | Exclude | Include | Include | Include | Include | Include |
Dietary Patterns and Breast, Colorectal, Lung, and Prostate Cancer | Exclude | Include | Include | Include | ||
Dietary Patterns and Bone Health | Exclude | Include | Include | Include | Include | Include |
Dietary Patterns and Neurocognitive Health | Exclude | Include (only at intervention or exposure) | Include | Include | Include | Include |
Systematic Review | Age or Life Stage of Study Participants at Intervention or Exposure and Outcomea,b | |||||
---|---|---|---|---|---|---|
Infants (birth to 24 months) | Children (2–18 years) | Adults (19–64 years) | Older Adults (65 years and older) | Women During Pregnancy | Women During Lactation | |
Dietary Patterns and Sarcopenia | Exclude | Exclude (ages 2–12 years at intervention or exposure) Exclude (ages 2–18 years at outcome) Include (ages 12–18 years at intervention or exposure) | Include | Include | Exclude | Exclude |
Dietary Patterns and All-Cause Mortality | Exclude | Include | Include | Include | Exclude | Exclude |
Pregnancy and Lactation | ||||||
Dietary Patterns During Pregnancy and Gestational Weight Gain | Includec,d,e | |||||
Dietary Patterns During Lactation and Postpartum Weight Loss | Includec,d,f,g | |||||
Dietary Patterns During Lactation and Human Milk Composition and Quantity | Includeh,i |
Systematic Review | Age or Life Stage of Study Participants at Intervention or Exposure and Outcomea,b | |||||
---|---|---|---|---|---|---|
Infants (birth to 24 months) | Children (2–18 years) | Adults (19–64 years) | Older Adults (65 years and older) | Women During Pregnancy | Women During Lactation | |
Dietary Patterns During Lactation and Developmental Milestones, Including Neurocognitive Development, in the Child | Include (at outcome) | Include (at outcome) | Exclude (at outcome) | Exclude (at outcome) | Include (at intervention or exposure) | |
Folic Acid from Fortified Foods and/or Supplements During Pregnancy and Lactation and Health Outcomes | Includej | Includej | Excludej | Excludej | Includek,l | Includek,m |
Omega-3 Fatty Acids from Supplements Consumed Before and During Pregnancy and Lactation and Developmental Milestones, Including Neurocognitive Development, in the Child | Include (at outcome) | Include (at outcome) | Exclude (at outcome) | Exclude (at outcome) | Includec,d,e,n (at intervention or exposure) | Includec,d,e (at intervention or exposure) |
Systematic Review | Age or Life Stage of Study Participants at Intervention or Exposure and Outcomea,b | |||||
---|---|---|---|---|---|---|
Infants (birth to 24 months) | Children (2–18 years) | Adults (19–64 years) | Older Adults (65 years and older) | Women During Pregnancy | Women During Lactation | |
Maternal Diet During Pregnancy and Lactation and Risk of Child Food Allergies and Atopic Allergic Diseases | Included (at outcomes: food allergies, atopic dermatitis, and allergic rhinitis) Excluded (at outcomes: asthma) |
Included (at all outcomes) | Excluded (at all outcomes) | Excluded (at all outcomes) | Include (at intervention or exposure) | Includeo (at intervention or exposure) |
Birth to 24 Months | ||||||
The Duration, Frequency, and Volume of Exclusive Human Milk and/or Infant Formula Consumption and Overweight and Obesity | Includep (at intervention or exposure and at outcome: rapid weight gain) | Includep (at outcome) | Includep (at outcome) | Includep (at outcome) | ||
The Duration, Frequency, and Volume of Exclusive Human Milk and/or Infant Formula Consumption and Nutrient Status | Include | Exclude | Exclude | Exclude |
Systematic Review | Age or Life Stage of Study Participants at Intervention or Exposure and Outcomea,b | |||||
---|---|---|---|---|---|---|
Infants (birth to 24 months) | Children (2–18 years) | Adults (19–64 years) | Older Adults (65 years and older) | Women During Pregnancy | Women During Lactation | |
Iron from Supplements Consumed During Infancy and Toddlerhood and Growth, Size, and Body Composition | Include | Include (at outcome) | Include (at outcome) | Include (at outcome) | ||
Vitamin D from Supplements Consumed during Infancy and Toddlerhood and Bone Health | Include | Include (at outcome) | Exclude | Exclude | ||
Beverages and Added Sugars | ||||||
Beverage Consumption and Growth, Size, Body Composition, and Risk of Overweight and Obesity | Exclude | Includeq | Includeq | Includeq | Includeq | Includeq |
Beverage Consumption During Pregnancy and Birth Weight | Include | Includec,d,e,r | ||||
Alcohol Consumption and All-Cause Mortality | Includeq,s | Includeq,s |
Systematic Review | Age or Life Stage of Study Participants at Intervention or Exposure and Outcomea,b | |||||
---|---|---|---|---|---|---|
Infants (birth to 24 months) | Children (2–18 years) | Adults (19–64 years) | Older Adults (65 years and older) | Women During Pregnancy | Women During Lactation | |
Added Sugars Consumption and Risk of Cardiovascular Disease | Includeq (at intervention or exposure) | Includeq | Includeq | Includeq | ||
Dietary Fats and Seafood | ||||||
Types of Dietary Fat and Cardiovascular Disease | Includet | Includet | Include | Include | Include | Include |
Seafood Consumption During Pregnancy and Lactation and Neurocognitive Development in the Child | Include (at outcome) | Include (at outcome) | Exclude (at outcome) | Exclude (at outcome) | Include (at intervention or exposure) | Include (at intervention or exposure) |
Seafood Consumption During Childhood and Adolescence and Neurocognitive Development | Include (at intervention or exposure) | Include | Include (at outcome) | Include (at outcome) | ||
Seafood Consumption During Childhood and Adolescence and Cardiovascular Disease | Include (at intervention or exposure) | Includet | Include (at outcome) | Include (at outcome) | ||
Frequency of Eating |
Systematic Review | Age or Life Stage of Study Participants at Intervention or Exposure and Outcomea,b | |||||
---|---|---|---|---|---|---|
Infants (birth to 24 months) | Children (2–18 years) | Adults (19–64 years) | Older Adults (65 years and older) | Women During Pregnancy | Women During Lactation | |
Frequency of Eating and Growth, Size, Body Composition, and Risk of Overweight and Obesity | Exclude | Include | Include | Include | Includeu | |
Frequency of Eating and Cardiovascular Disease | Exclude | Include | Include | Include | Includeu | |
Frequency of Eating and Type 2 Diabetes | Exclude | Include | Include | Include | Includeu | |
Frequency of Eating During Lactation and Postpartum Weight Loss | Includec,d,f,g,v | |||||
Frequency of Eating During Pregnancy and Gestational Weight Gain | Includec,d,f,w | |||||
Frequency of Eating and All-Cause Mortalityx | Includeu |
* Data in this table are from the Inclusion and Exclusion Criteria tables provided in each systematic review.
a All systematic reviews excluded non-human participants (e.g., animal or in vitro models).
b Age of study participants is at intervention/exposure and outcome, unless otherwise noted.
c Excluded pregnancies conceived only using assisted reproductive technologies.
d Excluded studies that only enroll multiple gestation pregnancies.
e Excluded studies that enroll both singleton and multiple pregnancies and do not account for singleton and multiple gestation in the design or analyses and only present aggregate findings.
f Excluded studies that only report combined data for singleton and multiple gestation pregnancies.
g Excluded studies that enroll lactating and non-lactating mothers and only present combined data for lactating and non-lactating mothers.
h Included study participants who were exclusively or predominantly human milk feeding women (human milk quantity outcome). Included women during lactation (human milk composition outcome).
i Excluded studies that only enroll multiple gestation pregnancies or present only combined analyses of singleton and multiple gestations (human milk quantity outcome only).
j At outcomes: developmental milestones including neurocognitive development.
k Excluded studies that exclusively enroll multiple gestation pregnancies or exclusively present combined analyses of singleton and multiple gestations.
l Included studies conducted in women up to 6 months before pregnancy (at intervention or exposure). Included studies of women during pregnancy at intervention or exposure and outcomes (micronutrient status, gestational diabetes, hypertensive disorders).
m At intervention or exposure and outcomes (micronutrient status, milk composition).
n Included studies conducted in women up to 6 months before pregnancy (at intervention or exposure).
o Excluded studies conducted exclusively in non-lactating women or in lactating women who are not exclusively or predominantly feeding human milk.
p Additional criteria for within-family studies of siblings. Included siblings with discordant exposures or outcomes or both who were compared using within-family analyses. Excluded siblings who were not compared using within-family analyses.
q Excluded hospitalized samples.
r Included women who were pregnant or capable of becoming pregnant. Excluded hospitalized patients, when hospitalization is not related to pregnancy, birth and immediate postpartum.
s Included studies conducted primarily in adults 21 years and older and studies that enroll some participants under 21 years of age. Excluded studies that exclusively enroll participants under 21 years old.
t Included at intervention or exposure and intermediate outcomes only.
u Included women during pregnancy and the post-partum period.
v Included women who are post-partum and who are lactating.
w Included women who pregnant or who are capable of becoming pregnant.
x The systematic review included males and females, but no age groups were specified.
Systematic Review | Include | Exclude |
---|---|---|
Dietary Patterns | ||
Dietary Patterns and Growth, Size, Body Composition, and/or Risk of Overweight or Obesity |
|
|
Dietary Patterns and Risk of Cardiovascular Disease |
|
|
Systematic Review | Include | Exclude |
---|---|---|
Dietary Patterns and Risk of Type 2 Diabetes |
|
|
Dietary Patterns and Breast, Colorectal, Lung, and Prostate Cancer |
|
|
Dietary Patterns and Bone Health |
|
|
Systematic Review | Include | Exclude |
---|---|---|
Dietary Patterns and Neurocognitive Health |
|
|
Dietary Patterns and Sarcopenia |
|
|
Dietary Patterns and All-Cause Mortality |
|
|
Systematic Review | Include | Exclude |
---|---|---|
Pregnancy and Lactation | ||
Dietary Patterns During Pregnancy and Gestational Weight Gain |
|
|
Dietary Patterns During Lactation and Postpartum Weight Loss |
|
|
Dietary Patterns During Lactation and Human Milk Composition and Quantity |
|
|
Systematic Review | Include | Exclude |
---|---|---|
Dietary Patterns During Lactation and Developmental Milestones, Including Neurocognitive Development, in the Child |
|
|
Folic Acid from Fortified Foods and/or Supplements During Pregnancy and Lactation and Health Outcomes |
|
|
Systematic Review | Include | Exclude |
---|---|---|
Omega-3 Fatty Acids from Supplements Consumed Before and During Pregnancy and Lactation and Developmental Milestones, Including Neurocognitive Development, in the Child |
|
|
Maternal Diet During Pregnancy and Lactation and Risk of Child Food Allergies and Atopic Allergic Diseases |
|
|
Systematic Review | Include | Exclude |
---|---|---|
Birth to 24 Months | ||
The Duration, Frequency, and Volume of Exclusive Human Milk and/or Infant Formula Consumption and Overweight and Obesity |
Studies that enroll participants:
Studies that enroll some participants:
|
Studies that exclusively enroll participants:
|
The Duration, Frequency, and Volume of Exclusive Human Milk and/or Infant Formula Consumption and Nutrient Status |
Studies that enroll participants:
Studies that enroll some participants:
|
Studies that exclusively enroll participants:
|
Systematic Review | Include | Exclude |
---|---|---|
Iron from Supplements Consumed During Infancy and Toddlerhood and Growth, Size, and Body Composition |
|
|
Vitamin D from Supplements Consumed During Infancy and Toddlerhood and Bone Health |
|
|
Beverages and Added Sugars | ||
Beverage Consumption and Growth, Size, Body Composition, and Risk of Overweight and Obesity |
|
|
Systematic Review | Include | Exclude |
---|---|---|
Beverage Consumption During Pregnancy and Birth Weight |
|
|
Alcohol Consumption and All-Cause Mortality |
|
Studies that exclusively enroll participants diagnosed with a disease or hospitalized with an illness or injury. (For this criterion, studies that exclusively enroll subjects with obesity will not be excluded.) |
Systematic Review | Include | Exclude |
---|---|---|
Added Sugars Consumption and Risk of Cardiovascular Disease |
|
|
Systematic Review | Include | Exclude |
---|---|---|
Dietary Fats and Seafood | ||
Types of Dietary Fat and Cardiovascular Disease |
|
|
Systematic Review | Include | Exclude |
---|---|---|
Seafood Consumption During Pregnancy and Lactation and Neurocognitive Development in the Child |
|
|
Seafood Consumption during Childhood and Adolescence and Neurocognitive Development |
|
|
Systematic Review | Include | Exclude |
---|---|---|
Seafood Consumption During Childhood and Adolescence and Cardiovascular Disease |
|
|
Frequency of Eating | ||
Frequency of Eating and Growth, Size, Body Composition, and Risk of Overweight and Obesity |
|
|
Systematic Review | Include | Exclude |
---|---|---|
Frequency of Eating and Cardiovascular Disease |
|
|
Frequency of Eating and Type 2 Diabetes |
|
|
Systematic Review | Include | Exclude |
---|---|---|
Frequency of Eating During Lactation and Postpartum Weight Loss |
|
|
Frequency of Eating During Pregnancy and Gestational Weight Gain |
|
|
Frequency of Eating and All-Cause Mortality |
|
|
Inclusion Criteria* | Exclusion Criteria** |
---|---|
|
|
* Unless noted otherwise, all systematic reviews included studies that met these criteria.
** Unless noted otherwise, all systematic reviews excluded studies that met these criteria.
a Mendelian randomization studies were included in only one systematic review: Alcohol Consumption and All-Cause Mortality.
b Cross-sectional studies were included in two systematic reviews: (1) Folic Acid from Fortified Foods and/or Supplements During Pregnancy and Lactation and Health Outcomes and (2) The Duration, Frequency, and Volume of Exclusive Human Milk and/or Infant Formula Consumption and Overweight and Obesity. In the review on folic acid, cross-sectional studies were included for outcomes of human milk composition. In this same review, cross-sectional studies were excluded for outcomes of micronutrient status, gestational diabetes, hypertensive disorders, developmental milestones, including neurocognitive health. In the review on human milk and/or infant formula consumption, cross-sectional studies were included for within-family studies of siblings.
c Uncontrolled before-and-after studies were included in one systematic review: Folic Acid from Fortified Foods and/or Supplements during Pregnancy and Lactation and Health Outcomes.
d Obesity treatment studies were excluded in only one systematic review: Beverage Consumption and Growth, Size, Body Composition, and Risk of Overweight and Obesity.
Table C-5 Summary of Approach to Answering Questions in the 2020 DGAC Scientific Reporta
Topic | Question | Approach |
---|---|---|
Current Intakes of Foods, Beverages, and Nutrients | 1-5 | Data analysis |
Food, Beverage and Nutrient Composition During Pregnancy | 1,2,5,6 | Existing NESR systematic reviewb |
3,4,7,8,9,10,11 | NESR systematic reviewc | |
Food Beverage and Nutrition Consumption During Lactation | 1-8 | NESR systematic reviewc |
Human Milk and/or Infant Formula Feeding | 1,3 | NESR systematic reviewc |
2,4 | Existing NESR systematic reviewb | |
Foods and Beverages Consumed During Infancy and Toddlerhood | 1-5 | Existing NESR systematic reviewb |
6-8 | NESR systematic reviewc | |
Nutrients from Dietary Supplements During Infancy and Toddlerhood | 1,2 | NESR systematic reviewc |
USDA Food Patterns for Children Younger than Age 24 Months | 1 | Food Pattern Modeling |
Dietary Patterns | 1-8 | NESR systematic reviewc |
Dietary Fats and Seafood | 1-3 | NESR systematic reviewc |
Beverages | 1 | Data analysis |
2 | NESR systematic reviewc | |
Alcoholic Beverages | 1 | Data analysis |
2 | NESR systematic reviewc | |
Topic | Question | Approach |
---|---|---|
Added sugars | 1 | Data analysis |
2 | NESR systematic reviewc | |
3 | Food Pattern Modeling | |
Frequency of Eating | 1 | Data analysis |
2-5 | NESR systematic reviewc | |
USDA Food Patterns for Individuals Ages 2 Years and Older | 1 | Food pattern modeling |
NESR, Nutrition Evidence Systematic Review
a Information used for this table was extracted from Part D of the 2020 DGAC Scientific Review.
b See 2020 DGAC Scientific Report for further details.
c See 2020 DGAC Scientific Report and nesr.usda.gov for information on these systematic reviews.
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