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Introduction

BACKGROUND FOR THE STUDY

The Dietary Guidelines for Americans

The Dietary Guidelines for Americans (DGA) serve as the cornerstone of federal nutrition policy and nutrition education activities. The first edition to the DGA was published in 1980 with the pamphlet Nutrition and Your Health: Dietary Guidelines for Americans (USDA and HHS, 1980). In 1990, Congress passed the National Nutrition Monitoring and Related Research Act,¹ which mandated that the U.S. Department of Agriculture (USDA) and the U.S. Department of Health and Human Services (HHS) jointly publish the DGA at least every 5 years (DGA, n.d.-a). The law further required that the guidelines be “based on the preponderance of scientific and medical evidence, which is current at the time the report is prepared” (DGA, n.d.-b). The most recent edition is the Dietary Guidelines for Americans, 2020–2025 (2020–2025 DGA) (USDA and HHS, 2020).²

The DGA provides food-based recommendations to promote health, help prevent diet-related disease, and meet nutrient needs for all Americans (DGA, n.d.-a). It also serves as a fundamental resource to the federal government to maintain the currency of its food and nutrition programs

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¹ National Nutrition Monitoring and Related Research Act of 1990, Public Law 101-445, 101st Cong. (October 22, 1990), 7 U.S.C. 5341, 104 Stat. 1042–1044.

² See https://www.dietaryguidelines.gov (accessed December 7, 2021).

and initiatives.³ The DGA further inform the development of science-based nutrition education materials for both the general public and specific audiences, such as pregnant and lactating individuals, infants, children, and older adults (DGA, n.d.-a). Private organizations use the DGA for program guidance and development as well as education. Industry uses the guidelines in various ways, including product development and consumer messaging.

Since the 1985 edition of the DGA, a discretionary federal advisory committee has been re-established every 5 years to provide advice to USDA and HHS for their use in developing the next edition of the Dietary Guidelines.⁴ This group is known as the Dietary Guidelines Advisory Committee (DGAC), which is convened under the Federal Advisory Committee Act. The committee’s role is to review the body of evidence on topics relevant to the guidelines and to provide science-based advice to the secretaries of USDA and HHS to be used in developing the next edition of the DGA (DGA, n.d.-a). As a part of its work, the DGAC convenes public meetings and receives public comments. The product of the DGAC’s work is a scientific report that is submitted to the secretaries of USDA and HHS. The DGAC Scientific Report is a synthesis of the evidence supporting the committee’s recommendations to the federal government for the development of the next edition of the DGA (DGA, n.d.-a). Following submission of the report to the departments, the public has opportunities to provide both written comments and oral testimony to USDA and HHS. As subsequent editions of DGA are developed, USDA and HHS consider collectively the previous DGAC Scientific Report, input from federal agencies, public comments, and existing resource documents, such as the Dietary Reference Intakes.

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³ Nutrition assistance programs offered by USDA include the Supplemental Nutrition Assistance Program; the Special Supplemental Nutrition Program for Women, Infants, and Children; the National School Lunch and School Breakfast (School Meals) Programs, including summer food service; the Child and Adult Care Food Program; Food Assistance for Disaster Relief; the Emergency Food Assistance Program; the Food Distribution Program on Indian Reservations; and food distribution programs such as the Commodity Supplemental Food Program. See https://www.fns.usda.gov/programs (accessed December 7, 2021).

⁴Discretionary advisory committee means any advisory committee that is established under the authority of an agency head or authorized by statute. An advisory committee referenced in general (nonspecific) authorizing language or congressional committee report language is discretionary, and its establishment or termination is within the legal discretion of an agency head. Other types of advisory committees include independent Presidential advisory committees, nondiscretionary advisory committees, and Presidential advisory committees. See http://www.gsa.gov/portal/mediaId/218007/fileName/FACAFinalRule_R2E-NZ_0Z5RDZ-i34K-pR.action (accessed December 7, 2021).

Redesigning the Process for Establishing the Dietary Guidelines for Americans

The 2015 DGAC Scientific Report concluded that

The report also noted that “a diet higher in plant-based foods … and lower in calories and animal-based foods is more health-promoting and is associated with less environmental impact than is the current U.S. diet” (DGAC, 2015, p. 5). Together these conclusions and findings elicited a strong response, particularly from the beef industry, as recounted by Nestle (Nestle, 2018). The 2015–2020 DGA did not include a recommendation to limit meat or include the term “sustainability” (HHS and USDA, 2015). Particular issues at that time also included how the members of the DGAC were selected, how dietary patterns were modeled, the transparency and trustworthiness of the DGA and their acceptance by the public.

To address these issues, Congress—after a lobbying effort (Nestle, 2018)—in 2016, appropriated funds to USDA to engage the National Academies of Sciences, Engineering, and Medicine (the National Academies) to conduct a comprehensive study of the process used by USDA and HHS to develop the DGA.⁵ The National Academies convened the Committee on Redesigning the Process for Establishing the Dietary Guidelines for Americans (2017 committee) to undertake the study. The study produced two reports that provided recommendations for updating the process to develop future editions of the DGA (NASEM, 2017a,b). In the second report, which is the focus of this study, the 2017 committee was asked to make recommendations for how the Nutrition Evidence Library (NEL) could include more rigorous and objective scientific standards, how systematic reviews should be conducted on long-standing DGA recommendations, and how the DGA’s recommendations can better prevent chronic disease, ensure nutritional sufficiency for all Americans, and accommodate age, gender, metabolic health, and other factors (NASEM, 2017b). The 2017 committee’s review of evidence included examination of the processes of other guideline-forming bodies, literature reviews, USDA and HHS listening sessions, invited speakers, and public comments. This

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⁵ Consolidated Appropriations Act, 2016, Public Law 114-113, 114th Cong. (December 18, 2015), 129 Stat. 2280–2281.

evidence led the 2017 committee to three overarching conclusions, shown in Box 1-1. In forming its recommendations, the 2017 committee envisioned a process that is continuous from the end of the previous cycle to the beginning of the next.

Recommendation 1: The secretaries of the U.S. Department of Agriculture (USDA) and the U.S. Department of Health and Human Services (HHS) should redesign the Dietary Guidelines for Americans (DGA) process to prioritize topics to be reviewed in each DGA cycle, and redistribute the current functions of the Dietary Guidelines Advisory Committee to three separate groups:

1. Dietary Guidelines Planning and Continuity Group to monitor and curate evidence generation, to identify and prioritize topics for inclusion in the DGA, and to provide strategic planning support across DGA cycles;
2. Technical expert panels to provide content and methodological consultation during evaluation of the evidence; and
3. Dietary Guidelines Scientific Advisory Committee to interpret the scientific evidence and draw conclusions.

Recommendation 2: The secretaries of the U.S. Department of Agriculture and the U.S. Department of Health and Human Services should provide the public with a clear explanation when the Dietary Guidelines for Americans omit or accept only parts of conclusions from the scientific report.

Recommendation 3: The secretary of U.S. Department of Agriculture (USDA) should clearly separate the roles of USDA Nutrition Evidence Library (NEL) staff and the Dietary Guidelines Scientific Advisory Committee (DGSAC) such that

1. The NEL staff plan and conduct systematic reviews with input from technical expert panels, perform risk of bias assessment of individual studies, and assist the DGSAC as needed.
2. The NEL systematic reviews are externally peer reviewed prior to being made available for use by the DGSAC.
3. The DGSAC synthesizes and interprets the results of systematic reviews and draws conclusions about the entire body of evidence.

Recommendation 4: The secretary of the U.S. Department of Agriculture should ensure all Nutrition Evidence Library (NEL) systematic reviews align with best practices by

1. Enabling ongoing training of the NEL staff;
2. Enabling engagement with and learning from external groups on the forefront of systematic review methods;
3. Inviting external systematic review experts to periodically evaluate the NEL’s methods; and
4. Investing in technological infrastructure.

Recommendation 5: The secretaries of the U.S. Department of Agriculture and the U.S. Department of Health and Human Services should enhance food pattern modeling to better reflect the complex interactions involved, variability in intakes, and range of possible healthful diets.

Recommendation 6: The secretaries of the U.S. Department of Agriculture and the U.S. Department of Health and Human Services should standardize the methods and criteria for establishing nutrients of concern.

Recommendation 7: The secretaries of the U.S. Department of Agriculture and the U.S. Department of Health and Human Services should commission research and evaluate strategies to develop and implement systems approaches into the Dietary Guidelines for Americans (DGA). The selected strategies should then begin to be used to integrate systems mapping and modeling into the DGA process.

U.S. Department of Agriculture Response to Recommendations for Redesigning the Dietary Guidelines for Americans Process

As an outcome of the 2017 National Academies report recommendations, public feedback, and the agencies’ commitment to a transparent, inclusive, and science-driven process, USDA and HHS took steps to refine the process for the 2020–2025 DGA (USDA and HHS, 2020). This included a request by the agencies for public comments on the topics and scientific questions to be examined in the 2020–2025 edition. In addition, DGAC members were identified following a public nomination process; membership expertise was based on the selected topics and supporting scientific questions identified by USDA and HHS. In addition, the Nutrition Evidence Systematic Review (NESR), formerly NEL, supported the 2020 DGAC.

THE COMMITTEE’S TASK

The 2021 Agriculture Appropriations Bill, SEC 783, required that not later than 1 year after the date of enactment of the act (by December 28, 2021),

In response to this congressional request, the USDA Food and Nutrition Service asked the National Academies to carry out a study comparing the process to develop the Dietary Guidelines for Americans, 2020–2025 (USDA and HHS, 2020) to the seven recommendations included in the report Redesigning the Process for Establishing the Dietary Guidelines for Americans (NASEM, 2017b). The Health and Medicine Division of the National Academies established a committee with expertise in nutrition; dietary assessment; food pattern modeling; systematic review standards and methodologies; clinical nutrition research; systems science; epidemiology; program design and evaluation; life cycle nutrition; public health nutrition; statistics/biostatistics; nutrition education; nutrition policy research and development; federal nutrition program planning; health impact analysis; and continuous process improvement methodologies. The committee held an open meeting with subject-matter experts (see

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⁶ Agriculture, Rural Development, Food and Drug Administration, and Related Agencies Appropriations Act, 2020, H.R.3164, 116th Cong. (2019). See https://www.congress.gov/bill/116th-congress/house-bill/3164 (accessed December 6, 2021).

Appendix B) and worked in closed sessions and by conference calls to deliberate on its task (see Box 1-2). This report represents the outcome of the committee’s research and deliberations, findings, and conclusions informed by evidence, including that presented in the open session. The committee was not asked to provide recommendations.

ORGANIZATION OF THE REPORT

This midcourse report is organized into five chapters. In this chapter, the background for the study and the statement of task are described. In Chapter 2, the committee describes its interpretation of the task and its methodological approach to it. In Chapter 3, the committee discusses its analysis of the scientific methodologies, review protocols, and evaluation processes used to develop the 2020–2025 DGA, and specifically addresses each of the seven 2017 National Academies recommendations. Chapter 4 discusses the committee’s analysis of practices used by NESR to obtain the scientific studies used to develop the dietary guidelines relevant to diet-related metabolic disease compared to the committee-identified practices and rigorous standards in current peer-reviewed published studies. The committee’s overall conclusions are presented in Chapter 5. The committee may address additional elements for the first and second tasks and will address task 3, its analysis of how full implementation of the 2017 National Academies recommendations would have affected the 2020–2025 DGA, in the final report.

REFERENCES