Addressing misinformation about the Dietary Guidelines for Americans.

The Dietary Guidelines for Americans (DGA) provides science-based advice on dietary intake to promote health, reduce risk of chronic disease, and meet nutrient needs. It is jointly published by the United States Departments of Health and Human Services and Agriculture (USDA) every 5 y. As chronic diseases continue to rise to pervasive levels, helping the United States population follow the DGA is especially important for improving the health of our nation. The DGA is developed using a rigorous and transparent scientific process, and with the advice of an independent, external committee of leading scientists. Career federal nutrition scientists who manage the process ensure that the methods used to develop the DGA remain state of the art. Unfortunately, misinformation about the scientific basis, transparency, and relevance of the DGA for the United States population threatens its credibility. The main objective of this article is to correct this misinformation with factual information about the process used to develop the DGA. The DGA provides guidelines for the general public, and its primary audience includes policymakers and nutrition and health professionals who help individuals and families consume a healthy dietary pattern. Providing accurate information may bolster trust in the recommendations among these audiences while improving implementation across sectors to promote better adherence to the DGA, thereby improving diet quality among the United States population.

A tool to assess risk of bias in non-randomized follow-up studies of exposure effects (ROBINS-E).

BACKGROUND: Observational epidemiologic studies provide critical data for the evaluation of the potential effects of environmental, occupational and behavioural exposures on human health. Systematic reviews of these studies play a key role in informing policy and practice. Systematic reviews should incorporate assessments of the risk of bias in results of the included studies. OBJECTIVE: To develop a new tool, Risk Of Bias In Non-randomized Studies - of Exposures (ROBINS-E) to assess risk of bias in estimates from cohort studies of the causal effect of an exposure on an outcome. METHODS AND RESULTS: ROBINS-E was developed by a large group of researchers from diverse research and public health disciplines through a series of working groups, in-person meetings and pilot testing phases. The tool aims to assess the risk of bias in a specific result (exposure effect estimate) from an individual observational study that examines the effect of an exposure on an outcome. A series of preliminary considerations informs the core ROBINS-E assessment, including details of the result being assessed and the causal effect being estimated. The assessment addresses bias within seven domains, through a series of 'signalling questions'. Domain-level judgements about risk of bias are derived from the answers to these questions, then combined to produce an overall risk of bias judgement for the result, together with judgements about the direction of bias. CONCLUSION: ROBINS-E provides a standardized framework for examining potential biases in results from cohort studies. Future work will produce variants of the tool for other epidemiologic study designs (e.g. case-control studies). We believe that ROBINS-E represents an important development in the integration of exposure assessment, evidence synthesis and causal inference.

Dietary Patterns and Health: Insights From NESR Systematic Reviews to Inform the Dietary Guidelines for Americans.

This perspective article shares unique insights from the extensive experience of the US Department of Agriculture Nutrition Evidence Systematic Review branch in conducting systematic reviews on dietary patterns and health outcomes to inform the Dietary Guidelines for Americans. Methodological approaches for reviewing dietary patterns research are described, including approaches to operationalizing definitions and analyzing labeled dietary patterns. The review also describes techniques for synthesizing dietary patterns research across life stages in systematic reviews that inform food-based, federal dietary guidance. Current research activities and recommendations for how to improve or address gaps in dietary patterns research in the future are also discussed.

An equitable, community-engaged translational framework for science in human lactation and infant feeding-a report from "Breastmilk Ecology: Genesis of Infant Nutrition (BEGIN)" Working Group 5.

Human milk is the ideal source of nutrition for most infants, but significant gaps remain in our understanding of human milk biology. As part of addressing these gaps, the Breastmilk Ecology: Genesis of Infant Nutrition (BEGIN) Project Working Groups 1-4 interrogated the state of knowledge regarding the infant-human milk-lactating parent triad. However, to optimize the impact of newly generated knowledge across all stages of human milk research, the need remained for a translational research framework specific to the field. Thus, with inspiration from the simplified environmental sciences framework of Kaufman and Curl, Working Group 5 of the BEGIN Project developed a translational framework for science in human lactation and infant feeding, which includes 5 nonlinear, interconnected translational stages, T1: Discovery; T2: Human health implications; T3: Clinical and public health implications; T4: Implementation; and T5: Impact. The framework is accompanied by 6 overarching principles: 1) Research spans the translational continuum in a nonlinear, nonhierarchical manner; 2) Projects engage interdisciplinary teams in continuous collaboration and cross talk; 3) Priorities and study designs incorporate a diverse range of contextual factors; 4) Research teams include community stakeholders from the outset through purposeful, ethical, and equitable engagement; 5) Research designs and conceptual models incorporate respectful care for the birthing parent and address implications for the lactating parent; 6) Research implications for real-world settings account for contextual factors surrounding the feeding of human milk, including exclusivity and mode of feeding. To demonstrate application of the presented translational research framework and its overarching principles, 6 case studies are included, each illustrating research gaps across all stages of the framework. Applying a translational framework approach to addressing gaps in the science of human milk feeding is an important step toward the aligned goals of optimizing infant feeding across diverse contexts as well as optimizing health for all.

USDA Nutrition Evidence Systematic Review's collaborative approach for conducting systematic reviews: Promoting diversity of expertise while managing potential conflicts of interest.

U.S. Department of Agriculture's (USDA) Nutrition Evidence Systematic Review (NESR) Branch develops food-and nutrition-related systematic reviews and other evidence synthesis products. NESR has established itself as a key resource for the Federal government when making evidence-informed decisions related to public health nutrition, such as the development of the Dietary Guidelines for Americans. NESR's systematic review methodology is rigorous, protocol-driven, and highly collaborative. NESR's systematic reviews examine the complex interplay between diet and health with input and support from various collaborators, including Federal stakeholders, expert groups, and public stakeholders. Implementing NESR's rigorous methodology ensures that the appropriate steps are taken to minimize conflict of interest, producing systematic reviews that are high-quality, trustworthy, and useful to end users who make decisions based on their findings. This article describes how NESR's systematic review process leverages a diversity of expertise and experience, while managing potential conflicts of interest. It describes the groups who collaborate to conduct NESR systematic reviews, their expertise, and why their involvement is critical for ensuring the rigor and utility of NESR's work.

Strengthening Research that Answers Nutrition Questions of Public Health Importance: Leveraging the Experience of the USDA Nutrition Evidence Systematic Review Team.

The Nutrition Evidence Systematic Review (NESR) team conducts nutrition- and public health-related systematic reviews and is within the USDA's Center for Nutrition Policy and Promotion. NESR has collaborated with scientific experts to conduct systematic reviews on nutrition and public health topics for more than a decade and is uniquely positioned to share recommendations with the research community to strengthen research quality and impact, especially the evidence base that supports public health nutrition guidance, including future editions of the Dietary Guidelines for Americans. Leveraging the expertise of NESR and its systematic review process resulted in the following recommendations for the research community: a) use the strongest study design feasible with sufficient sample size(s); b) enroll study participants who reflect the diversity of the population of interest and report participant characteristics; c) use valid and reliable dietary assessment methods; d) describe the interventions or exposures of interest and use standard definitions to promote consistency; e) use valid and reliable health outcome measures; f) account for variables that may impact the relationship between nutrition-related interventions or exposures and health outcomes; g) carry out studies for a sufficient duration and include repeated measures, as appropriate; and h) report all relevant information to inform accurate interpretation and evaluation of study results. Implementing these recommendations can strengthen nutrition and public health evidence and increase its utility in future public health nutrition systematic reviews. However, implementation will require additional support from the entire research community, including scientific journals and funding agencies.

Perspective: USDA Nutrition Evidence Systematic Review Methodology: Grading the Strength of Evidence in Nutrition- and Public Health-Related Systematic Reviews.

The USDA's Nutrition Evidence Systematic Review (NESR) team conducts food- and nutrition-related systematic reviews used to inform US Federal guidelines and programs, including the Dietary Guidelines for Americans. NESR's systematic review methodology includes a step to grade the strength of the evidence underlying conclusion statements, which is critical for ensuring that end users understand the level of certainty in conclusions when using them to make decisions. Over time, NESR has ensured its grading process not only remains state of the art but is also designed specifically for systematic reviews that inform Federal guidelines and programs on nutrition and public health. The NESR grading process used by the 2020 Dietary Guidelines Advisory Committee included 5 grading elements: risk of bias, consistency, directness, precision, and generalizability. Evidence was grouped by study design and assessed against these elements, and the grade assigned to the entire body of evidence took into consideration the strengths and limitations of each design. Based on this assessment, 1 of 4 grades was assigned: strong, moderate, limited, or grade not assignable. The grade was clearly communicated by integrating specific language into each conclusion statement (e.g., "strong evidence demonstrates" or "limited evidence suggests"), and supported by rationale documented in the review. NESR's grading process aligns with approaches used by other organizations that conduct systematic reviews, while retaining aspects unique to NESR's role in informing Federal nutrition and public health guidelines and programs. It provides a framework that promotes consistency in grading across food- and nutrition-related reviews, while offering flexibility that allows for thorough consideration of the body of evidence underlying an individual conclusion statement. NESR's rigorous and transparent methods for grading the strength of evidence in food- and nutrition-related systematic reviews ensure that decisions related to nutrition and public health are based on the strongest available evidence.

Evaluation of Dietary Patterns and All-Cause Mortality: A Systematic Review.

Importance: The 2020 Dietary Guidelines Advisory Committee conducted a systematic review of existing research on diet and health to inform the current Dietary Guidelines for Americans. The committee answered this public health question: what is the association between dietary patterns consumed and all-cause mortality (ACM)? Objective: To ascertain the association between dietary patterns consumed and ACM. Evidence Review: Guided by an analytical framework and predefined inclusion and exclusion criteria developed by the committee, the US Department of Agriculture's Nutrition Evidence Systematic Review (NESR) team searched PubMed, the Cochrane Central Register of Controlled Trials, and Embase and dual-screened the results to identify articles that were published between January 1, 2000, and October 4, 2019. These studies evaluated dietary patterns and ACM in participants aged 2 years and older. The NESR team extracted data from and assessed risk of bias in included studies. Committee members synthesized the evidence, developed conclusion statements, and graded the strength of the evidence supporting the conclusion statements. Findings: A total of 1 randomized clinical trial and 152 observational studies were included in the review. Studies enrolled adults and older adults (aged 17-84 years at baseline) from 28 countries with high or very high Human Development Index; 53 studies originated from the US. Most studies were well designed, used rigorous methods, and had low or moderate risks of bias. Precision, directness, and generalizability were demonstrated across the body of evidence. Results across studies were highly consistent. Evidence suggested that dietary patterns in adults and older adults that involved higher consumption of vegetables, fruits, legumes, nuts, whole grains, unsaturated vegetable oils, fish, and lean meat or poultry (when meat was included) were associated with a decreased risk of ACM. These healthy patterns were also relatively low in red and processed meat, high-fat dairy, and refined carbohydrates or sweets. Some of these dietary patterns also included intake of alcoholic beverages in moderation. Results based on additional analyses with confounding factors generally confirmed the robustness of main findings. Conclusions and Relevance: In this systematic review, consuming a nutrient-dense dietary pattern was associated with reduced risk of death from all causes.

Omega-3 Fatty Acid Dietary Supplements Consumed During Pregnancy and Lactation and Child Neurodevelopment: A Systematic Review.

BACKGROUND: Maternal nutrition during pregnancy and lactation has profound effects on the development and lifelong health of the child. Long-chain PUFAs are particularly important for myelination and the development of vision during the perinatal period. OBJECTIVES: We conducted a systematic review to examine the relationship between supplementation with omega-3 fatty acids during pregnancy and/or lactation and neurodevelopment in children, to inform the Scientific Report of the 2020 Dietary Guidelines Advisory Committee. METHODS: We identified articles on omega-3 fatty acid supplementation in pregnant and lactating women that included measures of neurodevelopment in their children (0-18 y) by searching PubMed, CENTRAL, Embase, and CINAHL Plus. After dual screening articles for inclusion, we qualitatively synthesized and graded the strength of evidence using pre-established criteria for assessing risk of bias, consistency, directness, precision, and generalizability. RESULTS: We included 33 articles from 15 randomized controlled trials (RCTs) and 1 prospective cohort study. Of the 8 RCTs that delivered omega-3 fatty acid dietary supplements during pregnancy alone (200-2200 mg/d DHA and 0-1100 mg/d EPA for approximately 20 wk), 5 studies reported ≥1 finding that supplementation improved measures of cognitive development in the infant or child by 6%-11% (P < 0.05), but all 8 studies also reported ≥1 nonsignificant (P > 0.05) result. There was inconsistent or insufficient evidence for other outcomes (language, social-emotional, physical, motor, or visual development; academic performance; risks of attention deficit disorder, attention-deficit/hyperactivity disorder, autism spectrum disorder, anxiety, or depression) and for supplementation during lactation or both pregnancy and lactation. Populations with a lower socioeconomic status and adolescents were underrepresented and studies lacked racial and ethnic diversity. CONCLUSIONS: Limited evidence suggests that omega-3 fatty acid supplementation during pregnancy may result in favorable cognitive development in the child. There was insufficient evidence to evaluate the effects of omega-3 fatty acid supplementation during pregnancy and/or lactation on other developmental outcomes.

Breastfeeding and risk of overweight in childhood and beyond: a systematic review with emphasis on sibling-pair and intervention studies.

BACKGROUND: Breastfeeding is associated with a lower risk of subsequent overweight or obesity, but it is uncertain whether this is a causal relation because most studies have not adequately reduced risk of bias due to confounding. OBJECTIVES: The aim of this review was to examine whether 1) ever compared with never consuming human milk and 2) different durations of human milk consumption among infants fed human milk are related to later risk of overweight or obesity, with emphasis on sibling-pair and intervention studies. METHODS: The 2020 Dietary Guidelines Advisory Committee, together with the Nutrition Evidence Systematic Review team, conducted a systematic review of articles relevant to healthy full-term infants in countries with a high or very high level of human development. We searched PubMed, Embase, Cochrane, and CINAHL; dual-screened the results using predetermined criteria; extracted data from and assessed the risk of bias for each included study; qualitatively synthesized the evidence; developed conclusion statements; and graded the strength of the evidence. RESULTS: The review included 42 articles, including 6 cohorts with sibling-pair analyses and 1 randomized controlled trial of a breastfeeding promotion intervention. Moderate evidence suggested that ever, compared with never, consuming human milk is associated with a lower risk of overweight and obesity at ages 2 y and older, particularly if the duration of human milk consumption is >6 mo. However, residual confounding cannot be ruled out. Evidence was insufficient to determine the relation between the duration of any human milk consumption, among infants fed human milk, and overweight and/or obesity at age 2 y and older. CONCLUSIONS: Further research, using strong study designs, is needed to disentangle the complex relation between infant feeding practices and the risk of subsequent overweight or obesity, as well as the biological and behavioral mechanisms if the relation is causal.

Timing of introduction of complementary foods and beverages and growth, size, and body composition: a systematic review.

BACKGROUND: The systematic review described in this article was conducted as part of the USDA and Department of Health and Human Services Pregnancy and Birth to 24 Months Project. OBJECTIVES: The aim was to describe the relationship between timing of introduction of complementary foods and beverages (CFBs) and growth, size, and body-composition outcomes across the life span. METHODS: The literature was searched and selected using predetermined criteria. Data were extracted and risk of bias assessed for each included study. Evidence was qualitatively synthesized, conclusion statements were developed, and the strength of the evidence was graded. RESULTS: Eighty-one articles were included in this systematic review that addressed timing of CFB introduction relative to growth, size, and body-composition outcomes from infancy through adulthood. Moderate evidence suggests that introduction of CFBs between the ages of 4 and 5 mo compared with ∼6 mo is not associated with weight status, body composition, body circumferences, weight, or length among generally healthy, full-term infants. Limited evidence suggests that introduction of CFBs before age 4 mo may be associated with higher odds of overweight/obesity. Insufficient evidence exists regarding introduction at age ≥7 mo. CONCLUSIONS: Although several conclusions were drawn in this systematic review, additional research is needed to address gaps and limitations in the evidence on timing of introduction of CFBs and growth, size, and body composition, such as randomized controlled trials that examine multiple outcomes and/or CFB introduction between the ages of 4 and 6 mo, and research that accounts for potential confounders such as feeding practices and baseline growth status and considers issues of reverse causality.

Complementary feeding and food allergy, atopic dermatitis/eczema, asthma, and allergic rhinitis: a systematic review.

BACKGROUND: Nutrition during infancy and toddlerhood may influence health and disease prevention across the life span. Complementary feeding (CF) starts when human milk or infant formula is complemented by other foods and beverages, beginning during infancy and continuing to age 24 mo. OBJECTIVES: The aim of this study was to describe systematic reviews conducted for the USDA and the Department of Health and Human Services Pregnancy and Birth to 24 Months Project to answer the following question: What is the relationship between the timing of the introduction of complementary foods and beverages (CFBs), or types and amounts of CFBs consumed, and the development of food allergy, atopic dermatitis/eczema, asthma, and allergic rhinitis? METHODS: The literature was searched using 4 databases (CINAHL, Cochrane, Embase, PubMed) to identify articles published from January 1980 to February 2017 that met predetermined inclusion criteria. For each study, data were extracted and risk of bias was assessed. The evidence was qualitatively synthesized to develop a conclusion statement, and the strength of the evidence was graded. RESULTS: Thirty-one included articles addressed the timing of CFB introduction, and 47 articles addressed the types and amounts of CFBs consumed. CONCLUSIONS: Moderate evidence suggests that there is no relationship between the age at which CF first begins and the risk of developing food allergy, atopic dermatitis/eczema, or childhood asthma. Limited to strong evidence, depending on the specific food, suggests that introducing allergenic foods in the first year of life (after 4 mo) does not increase the risk of food allergy and atopic dermatitis/eczema but may prevent peanut and egg allergy. There is not enough evidence to determine a relationship between diet diversity or dietary patterns and atopic disease. Research is needed to address gaps and limitations in the evidence on CF and atopic disease, including research that uses valid and reliable diagnostic measures and accounts for key confounders and potential reverse causality.

Types and amounts of complementary foods and beverages consumed and growth, size, and body composition: a systematic review.

BACKGROUND: Systematic reviews (SRs) were conducted by the Nutrition Evidence Systematic Review (NESR) team for the USDA's and the Department of Health and Human Services' Pregnancy and Birth to 24 Months Project. OBJECTIVES: The aim was to describe the SRs examining the relationship between types and amounts of complementary foods and beverages (CFBs) and growth, size, and body-composition outcomes. METHODS: The NESR team collaborated with subject matter experts to conduct this SR. The literature was searched and screened using predetermined criteria. For each included study, data were extracted and risk of bias was assessed. The evidence was qualitatively synthesized to develop a conclusion statement, and the strength of evidence was graded. RESULTS: This SR includes 49 articles that examined type, amount, or both of CFBs consumed and growth, size, and body-composition outcomes. Moderate evidence suggests that consuming either different amounts of meat, meat instead of iron-fortified cereal, or types of CFBs with different fats or fatty acids does not favorably or unfavorably influence growth, size, or body composition. In relation to overweight/obesity, insufficient evidence is available with regard to the intake of meat or CFBs with different fats or fatty acids. Limited evidence suggests that type and amount of fortified infant cereal does not favorably or unfavorably influence growth, size, body composition, or overweight/obesity. Limited evidence suggests that sugar-sweetened beverage consumption during the complementary feeding period is associated with increased obesity risk in childhood but is not associated with other measures of growth, size, or body composition. Limited evidence showed a positive association between juice intake and infant weight-for-length and child body mass index z scores. Insufficient evidence is available on other CFBs or dietary patterns in relation to outcomes. CONCLUSIONS: Although several conclusions were drawn, additional research is needed that includes randomized controlled trials, examines a wider range of CFBs, considers issues of reverse causality, and adjusts for potential confounders to address gaps and limitations in the evidence.

Complementary feeding and micronutrient status: a systematic review.

BACKGROUND: Proper nutrition during early life is critical for growth and development. OBJECTIVES: The aim was to describe systematic reviews conducted by the Nutrition Evidence Systematic Review team for the USDA and the Department of Health and Human Services Pregnancy and Birth to 24 Months Project to answer the following: What is the relation between 1) timing of introduction of complementary foods and beverages (CFBs) or 2) types and/or amounts of CFBs consumed and micronutrient status (iron, zinc, vitamin D, vitamin B-12, folate, and fatty acid status)? METHODS: A literature search identified articles from developed countries published from January 1980 to July 2016 that met the inclusion criteria. Data were extracted and risk of bias assessed. Evidence was qualitatively synthesized to develop a conclusion statement, and the strength of the evidence was graded. RESULTS: Nine articles addressed the timing of CFB introduction and 31 addressed types or amounts or both of CFBs. Moderate evidence suggests that introducing CFBs at age 4 mo instead of 6 mo offers no advantages or disadvantages in iron status among healthy full-term infants. Evidence is insufficient on the timing of CFB introduction and other micronutrient status outcomes. Strong evidence suggests that CFBs containing iron (e.g., meat, fortified cereal) help maintain adequate iron status or prevent deficiency in the first year among infants at risk of insufficient iron stores or low intake. Benefits for infants with sufficient iron stores (e.g., infant formula consumers) are less clear. Moderate evidence suggests that CFBs containing zinc (e.g., meat, fortified cereal) support zinc status in the first year and CFB fatty acid composition influences fatty acid status. Evidence is insufficient with regard to types and amounts of CFBs and vitamin D, vitamin B-12, and folate status, or the relation between lower-iron-containing CFBs and micronutrient status. CONCLUSIONS: Several conclusions on CFBs and micronutrient status were drawn from these systematic reviews, but more research that addresses specific gaps and limitations is needed.

Complementary feeding and developmental milestones: a systematic review.

BACKGROUND: Systematic reviews were conducted as part of the USDA and the US Department of Health and Human Services Pregnancy and Birth to 24 Months Project to examine the relation between complementary feeding and developmental milestones. OBJECTIVES: The aim of this study was to describe systematic reviews examining the relationship between timing of introduction of complementary foods and beverages (CFB), and the types and amounts of CFB consumed, and developmental milestones. METHODS: The literature was searched using 4 databases (PubMed, Cochrane, Embase, and CINAHL) to identify articles that met predetermined criteria for inclusion. Data extraction and risk of bias assessment were conducted for each included study. The body of evidence for each systematic review was qualitatively synthesized to develop a conclusion statement, and the strength of evidence was graded. RESULTS: Three included articles (1 randomized controlled trial; 2 observational studies) examined timing of introduction of CFB. Eight included articles (3 randomized controlled trials; 5 observational studies) examined types and amounts of CFB. There was insufficient evidence to draw conclusions about the relation between either timing of CFB introduction or types and amounts of CFB, and developmental milestones. CONCLUSIONS: The ability to draw conclusions about the relationship between complementary feeding and developmental milestones was restricted by an inadequate amount of evidence with potential for issues with reverse causality and wide variation in design, type/age of outcome assessment, exposure assessment, and reported results. Additional research to address these gaps and limitations would be useful.

Complementary feeding and bone health: a systematic review.

BACKGROUND: Proper nutrition during infancy and toddlerhood is crucial for supporting healthy growth and development, including bone health. Complementary feeding is the process that starts when human milk or infant formula is complemented by other foods and beverages, beginning during late infancy and continuing to 24 mo of age. OBJECTIVES: This article aims to describe systematic reviews (SRs) conducted by the Nutrition Evidence Systematic Review team for the USDA and the Department of Health and Human Services Pregnancy and Birth to 24 Months Project to answer these questions: what is the relationship between 1) timing of introduction of complementary foods and beverages (CFBs) or 2) types and/or amounts of CFBs consumed and bone health? Methods: The literature was searched with the use of 4 databases (CINAHL, Cochrane, Embase, and PubMed) to identify articles published from January 1980 to July 2016 that addressed these topics and met predetermined criteria for inclusion. For each study, data were extracted and risk of bias was assessed. The evidence was qualitatively synthesized to develop a conclusion statement, and the strength of the evidence was graded. RESULTS: Three articles addressed the timing of introduction of CFBs and bone health during childhood (through 18 y of age), and 2 addressed the types and/or amounts of CFBs consumed relative to bone health. CONCLUSIONS: Insufficient evidence was available to draw conclusions about the relationships between the timing of CFB introduction and types and/or amounts of CFBs consumed and bone health. Therefore, a grade was not assignable for these SRs. The ability to draw conclusions was limited by an overall lack of research, failure to adjust for several key confounding factors, and heterogeneity in studies with regard to methodology, subject populations, and results. Additional research is needed that addresses these gaps and limitations.

Systematic review methods for the Pregnancy and Birth to 24 Months Project.

The USDA's Nutrition Evidence Systematic Review (NESR) team specializes in conducting systematic reviews (SRs) to inform federal nutrition policy and programs. The NESR's dedicated staff collaborate with leading scientists to answer important food- and nutrition-related public health questions by objectively reviewing, evaluating, and synthesizing research using state-of-the-art methodology. NESR uses a rigorous, protocol-driven methodology that is designed to minimize bias; to ensure availability of SRs that are relevant, timely, and high quality; and to ensure transparency and reproducibility of findings. This article describes the methods used by NESR to conduct a series of SRs on diet and health in infants, toddlers, and women who are pregnant as part of the Pregnancy and Birth to 24 Months Project.

Executive summary: Evaluating the evidence base to support the inclusion of infants and children from birth to 24 mo of age in the Dietary Guidelines for Americans--"the B-24 Project".

The Dietary Guidelines for Americans (DGA) are the cornerstone of US government efforts to promote health and prevent disease through diet and nutrition. The DGA currently provides guidelines for ages ≥ 2 y. In an effort to determine the strength of the evidence to support the inclusion of infants and children from birth to age 24 mo, the partner agencies led by the Department of Health and Human Services Office of Disease Prevention and Health Promotion and the USDA Center for Nutrition Program and Policy initiated the project entitled "Evaluating the evidence base to support the inclusion of infants and children from birth to 24 months of age in the Dietary Guidelines for Americans--the B-24 Project." This project represents the first step in the process of applying systematic reviews to the process of deciding whether the evidence is sufficient to include this age group in future editions of the DGA. This supplement includes the B-24 Executive Summary, which describes the B-24 Project and the deliberations of the 4 working groups during the process of developing priority topics for the systematic review, and a research agenda to address the critical gaps. Also included in this supplement issue is an article on the Nutrition Evidence Library methodology for developing systematic review questions and articles from the invited content presenters at the B-24 Prime meeting.

USDA Nutrition Evidence Library: methodology used to identify topics and develop systematic review questions for the birth-to-24-mo population.

The USDA's Nutrition Evidence Library (NEL) specializes in conducting food- and nutrition-related systematic reviews that are used to inform federal government decision making. To ensure the utility of NEL systematic reviews, the most relevant topics must be addressed, questions must be clearly focused and appropriate in scope, and review frameworks must reflect the state of the science. Identifying the optimal topics and questions requires input from a variety of stakeholders, including scientists with technical expertise, as well as government policy and program leaders. The objective of this article is to describe the rationale and NEL methodology for identifying topics and developing systematic review questions implemented as part of the "Evaluating the evidence base to support the inclusion of infants and children from birth to 24 months of age in the Dietary Guidelines for Americans--the B-24 Project." This is the first phase of a larger project designed to develop dietary guidance for the birth to 24-mo population in the United States.