The Dietary Guidelines for Americans (DGA) have been produced collaboratively by the U.S. Departments of Agriculture (USDA) and the U.S. Department of Health and Human Services (HHS) since 1980. Nine editions have been produced to date, and federal law directs the DGA’s publication at least every five years. The Departments use “a highly prescribed process” to develop these guidelines, which represent many person-years of effort by federal staff members and the external experts who serve on the Dietary Guidelines Advisory Committee (DGAC). The DGA are “designed for policymakers and nutrition and health professionals to help all individuals and their families consume a healthy, nutritionally adequate diet” and this guidance forms the basis for federal nutrition policies and programs. Given its reach, this foundational document must meet the highest standards for scientific rigor and integrity.
The release of the Scientific Report of the 2015 DGAC elicited many public comments and questions about the process by which the DGA are created. These comments and a concern about the public’s trust in the DGA prompted Congress in 2016 to request USDA to engage the National Academies of Sciences, Engineering, and Medicine (the National Academies) to conduct a comprehensive study of the process used to establish the DGA. The National Academies convened the Committee on Redesigning the Process
1 This Summary does not include references. Citations for findings presented in the Summary appear in the subsequent chapters of the report.
for Establishing the Dietary Guidelines for Americans (2017 report committee), which produced two reports that together provided recommendations for updating the process to develop the DGA. The first report provided recommendations for selecting members of the DGAC. The second report, titled Redesigning the Process for Establishing the Dietary Guidelines for Americans (2017 National Academies report), provided seven recommendations (Box S-1) for changes to the process used to develop the DGA. The 2017 National Academies report stated values for improving the integrity of the process, which were to enhance transparency, manage overall bias and conflict of interest, promote diversity of expertise and experience, support a deliberative process, and adopt state-of-the-art processes and methods. The recommendations were designed to assist the Departments in maintaining success and preparing for the future.
THE COMMITTEE’S TASK AND APPROACH
In 2021, the Congressional Appropriations Act cited continued interest in the decision-making process leading to the development of the 2020–2025 DGA, particularly the extent to which USDA implemented the 2017 National Academies report recommendations. The overall task given to the Committee on Evaluating the Process to Develop the Dietary Guidelines for Americans, 2020–2025, was described by Congress, then the Departments created specific questions associated with each sub-task (see Box 1-2 for the full Statement of Task):
- A comparative analysis of methods, review protocols, and evaluation processes to develop the 2020–2025 DGA to the recommendations included in 2017 National Academies report.
- How did the process to develop the 2020–2025 DGA compare to the seven recommendations?
- A comparative analysis of the scientific studies used to develop the 2020–2025 DGA to the most current and rigorous scientific studies available.
- Did the criteria used to include scientific studies in the 2020–2025 DGA evidence base ensure that the evidence was current, rigorous, and generalizable?
- An analysis of how full implementation of the 2017 National Academies report recommendations would have affected the 2020–2025 DGA.
- How would the process with full implementation of the recommendations compared to the process used to develop the 2020-2025 DGA have affected the timeline, cost, and/or integrity of the most recently issued guidelines?
A noteworthy feature of this task is that it excludes providing recommendations, which the committee interpreted to include any expert opinion or advice regarding future implementation. To approach its task, the committee considered each recommendation as well as the 2017 National Academies report’s stated values. The committee issued its midcourse report, Evaluating the Process to Develop the Dietary Guidelines for
Americans, 2020–2025: A Midcourse Report, which described the committee’s research methodology and preliminary findings and conclusions for Tasks 1 and 2. The overarching conclusions for Task 2 are provided in Box S-2. Given that Task 3 built on Task 1, the evidence and the committee’s findings and conclusions for Task 3 presented in this final report include and supersede those for Task 1 presented in the midcourse report.
The committee interpreted Task 3 as a request to analyze how the 2020–2025 DGA would have differed in terms of timeline, cost, and integrity if the 2017 National Academies report recommendations had been fully implemented. Some recommendations were not implemented as recommended (even though the Departments might have taken steps to address them in other ways) and some were essentially fully implemented. For the remaining recommendations, the committee distinguished between those that were partially and those that were substantially implemented to indicate those that needed more or less additional work, respectively, to achieve full implementation. To approach Task 3, the committee developed a diagram (Figure S-1) to guide its analysis. It considered the DGA timeline and the cost to implement each recommendation as constraints to the process. The committee identified scientific rigor as necessary to achieve integrity as an outcome of the DGA process, and both are essential to the trustworthiness of the DGA process and product. When a recommendation was not implemented, the committee used its scientific expertise and judgment to reach its conclusions because implementation could have taken many forms.
The committee used information gathered during its response to Tasks 1 and 2, as well as additional evidence including federal reports and websites, scientific literature, and dialogue with the Departments through open sessions and written responses.
FINDINGS AND CONCLUSIONS FOR TASK 3
Recommendation 1 Findings
The committee found that the components of recommendation 1 were not implemented as proposed in the 2017 National Academies report. As a result, the duties of the DGAC were not redistributed to three new groups nor was a process for monitoring and curating scientific evidence established. However, the Departments made changes to distribute some of the functions of the DGAC, consistent with the intent
of recommendation 1 for the DGAC to focus on interpretation and integration of the data.
Improving the deliberative process used to create the DGA was a central theme of the 2017 National Academies report. The only substantial input from scientific experts outside of the federal government to the 2020–2025 DGA process was provided by the members of the DGAC. The committee found that such input is not currently available in the strategic planning process or the prioritization of systematic reviews, as the committee does not view the public comments that were solicited by the Departments as providing input equivalent to that obtained from greater involvement with external, subject-matter experts.
The committee found that there were not only barriers related to the timing and cost of implementing this recommendation during the process to develop the 2020–2025 DGA, but also non-trivial barriers to creating an additional federal advisory committee (i.e., the DGPCG). The alternative options considered by the 2017 report committee and discussed by the Departments would provide input that is neither continuous nor deliberative. As a result, new options are needed to create a process that operates continuously and involves deliberation with subject-matter experts external to the federal government. Thus, the committee finds it essential that strategic planning for the DGA and prioritization of the systematic reviews include the perspectives of experts from outside of the federal government to maximize benefits to all end users.
For recommendation 1a, the committee found that if there had been no other constraints, the process to create the DGPCG could have been in place for the process to create the 2025-2030 DGA. The committee had no information to determine whether different topics would have been chosen for review in the process of creating the 2020–2025 DGA if it had been possible to create the DGPCG. However, if this had been possible, strategic planning for the 2025–2030 DGA could have begun with the additional insights of external scientific experts as part of the DGPCG.
For recommendation 1b, the committee found that the recommendation was received too late for the technical expert panels (TEPs) to provide advance services for the DGAC. The committee determined that it was neither too late nor too costly to create TEPs for other uses. Nonetheless, the committee had no information to determine whether findings or conclusions would have differed if TEPs had been used.
For recommendation 1c, the committee had no information to determine whether the DGSAC would have evaluated the evidence differently and come to different conclusions than those developed for the 2020 DGAC Scientific Report if key responsibilities of the DGAC had been redistributed as recommended between the proposed TEPs and the DGSAC.
Recommendation 1 Conclusions
The major elements of recommendation 1, namely to redistribute the functions of the DGAC to three separate groups, were not implemented. The committee concluded that the Departments implemented changes to their process during the cycle to develop the 2020–2025 DGA that partially met the intent of redistributing some of the functions of the DGAC, and that the barriers to the creation of the DGPCG have not yet been overcome. As a result, full implementation of the redesign to create a more deliberative process has not yet been achieved. The committee concluded that there was no information to determine how full implementation of this foundational recommendation would have affected the 2020–2025 DGA. Moreover, not having created the DGPCG during the process of developing the 2020–2025 DGA means that the 2025–2030 DGA process has begun without strategic planning and insights from external scientific experts.
Recommendation 2 Findings
The committee found that recommendation 2 was substantially implemented. The great majority of recommendations by DGAC were followed; the number of differences was small relative to the large number of recommendations that did align.
The committee determined that two actions follow from recommendation 2. The first is to describe criteria for deciding whether DGAC Scientific Report and DGA recommendations are sufficiently different to require a public explanation. The second is to provide this explanation for each instance of sufficient differences, including a detailed description of how the “preponderance of scientific evidence” is both defined and interpreted in each case. For the process to develop the 2020–2025 DGA, no criteria were provided for deciding whether 2020 DGAC Scientific Report and DGA recommendations were sufficiently different to require a public explanation. Moreover, no detailed description of a “preponderance of scientific evidence” was provided.
The committee found that a full explanation of all differences between the 2020 DGAC Scientific Report and the 2020–2025 DGA would not have affected the content of the 2020–2025 DGA because these actions would have taken place after the establishment of the DGA.
Recommendation 2 Conclusions
The committee concluded that recommendation 2 was substantially implemented as the 2020–2025 DGA were largely aligned with the 2020 DGAC Scientific Report and the differences between the recommendations
for alcohol and added sugars were explained. However, full implementation of this recommendation would have contributed to improved transparency and, thus, integrity of the DGA.
Recommendation 3 Findings
The committee found that recommendation 3 was partially implemented. To separate the functions of the Nutrition Evidence Library (NEL) and DGSAC, the Departments made changes to the work of Nutrition Evidence Systematic Review (NESR [formerly NEL]) and the DGAC to address the recommended separation of roles.
For recommendation 3a, NESR and the 2020 DGAC were comprised of experts in both systematic reviews and topics relevant to the 2020–2025 DGA. The committee found that explicitly constituted TEPs were not created for systematic reviews performed after 2017 but the functions of a TEP were instead performed by the DGAC. This was possible because members of the DGAC were chosen for their expertise in the topics relevant to the 2020–2025 DGA. The committee did not have information to determine how the use of explicitly constituted TEPs would have changed the systematic review process.
For recommendation 3b, the committee found that peer review of the systematic reviews occurred for the first time, but it did not have information to identify constraints that would explain why experts external to the federal government were not included in the peer review as recommended, nor how including them would have changed the results of the systematic reviews.
For recommendation 3c, the committee found that, although the DGSAC was not created, the DGAC synthesized and interpreted the results of systematic reviews and drew conclusions independently of NESR. The committee did not have information to determine how the conclusions about the body of evidence would have differed if the proposed DGSAC had been created instead of the DGAC performing those functions.
Recommendation 3 Conclusions
The committee concluded that recommendation 3 was partially implemented. The 2017 National Academies report called for a clear separation of tasks between NESR and the DGSAC. While the roles of both NESR and DGAC were defined, the sharing of some tasks between groups indicates that some elements of this recommendation were not implemented as envisioned. The committee concluded that it was not possible to ascertain if or how the conclusions drawn from the systematic reviews, as well as the 2020–2025 DGA, would have differed if explicitly constituted TEPs
were used, external peer review was conducted, and the DGSAC had been created.
Recommendation 4 Findings
The committee found that, as part of the process to develop the 2020–2025 DGA that occurred before the DGAC was formed, improvements were made to align NESR with the best practices identified in the 2017 National Academies report. The committee found that NESR’s Continuous Quality Advancement (CQA) process engaged several leading systematic review organizations to evaluate nearly every component of the systematic review process. The committee found some methodological differences between practices of NESR and of these organizations, particularly the method to use and/or update existing systematic reviews, continuous evidence monitoring, and the methodology to assess the quality of evidence. The information about the CQA program did not document the criteria used to determine whether refinements to NESR’s processes are needed and what decisions had or had not been made. It is unclear if the differences between NESR practices and the committee-identified practices in its midcourse report had been previously identified or explored.
For recommendation 4a, the committee found that NESR has a strong CQA program, including both initial training for NESR staff and ongoing learning through participation in CQA interest groups (CQA-IGs) involving “landscape analysis” and assessment of methods and training materials for each component of the systematic review process from other leading organizations.
For recommendation 4b, the committee found that NESR listed many leading organizations that NESR had previously or were currently engaged with as part of the CQA-IGs.
For recommendation 4c, the committee found that, as part of the CQA-IG process, USDA invites experts to provide input on specific topics that NESR has identified. The committee had limited evidence to determine whether these experts are invited to evaluate overall NESR methods to identify other topics to explore.
The committee found that the current process for selecting CQA topics appears internally driven, with NESR staff identifying the topics based on input from key stakeholders. In contrast, the National Academies 2017 report recommended that both federal and non-federal experts should accomplish strategic planning and topic identification.
For recommendation 4d, the committee found that USDA invested in new software that facilitates data collection from and analysis of research used in the systematic review. The Departments also enhanced the DGA
website to promote public comment and transparency during the DGAC deliberations.
Recommendation 4 Conclusions
The committee concluded that recommendation 4 was substantially implemented. The strong CQA initiative to align NESR processes with best practices led to significant refinements, but other potential refinements were not addressed. The committee could not ascertain whether there would have been implications for the 2020–2025 DGA if the remaining NESR refinements or different refinements had been implemented. Both full implementation of this recommendation and maintaining best practices for conducting systematic reviews for population-level nutrition guidelines are critical for sustaining the rigor and integrity, and thus the trustworthiness, of the DGA.
Recommendation 5 Findings
The committee found that some refinements were made to the food pattern modeling used to develop the 2020–2025 DGA but that the analytic methods used did not change and TEPs were not employed to support the food pattern modeling. Enhancement of food pattern modeling is still needed to account for the heterogeneity of the population and its dietary patterns, specifically by incorporating systems modeling. The committee had limited information to determine how the recommended food patterns and the 2020–2025 DGA would have changed had methods designed to address the complexity of food intake patterns been applied.
Recommendation 5 Conclusions
The committee concluded that, although some refinements were made to the food pattern modeling used to develop the 2020–2025 DGA, the analytic methods used did not change. The committee had limited information to determine how the 2020–2025 DGA would have been affected by the full implementation of this recommendation. However, the lack of full implementation limits the capacity of the food patterns to reflect the heterogeneity of the population and variability of food patterns, with implications for the rigor of the DGA.
Recommendation 6 Findings
The committee found that the 2020 DGAC Scientific Report and a later peer-reviewed publication documented a framework that standardized the
terminology, thresholds, analytic methods, and interpretation related to nutrients of concern. The arbitrary thresholds proposed to identify nutrients of concern require further evaluation, including their consequences for different uses. The committee also found that the Departments have not yet publicly documented the descriptive data analyses commonly used across previous DGACs. Additionally, TEPs have not yet been employed to supplement the expertise of groups conducting descriptive data analyses. The descriptions in the 2017 National Academies report of analyses used in prior DGA cycles may have served as a partial documentation of these analyses in the interim.
This recommendation was almost fully implemented, with no effect expected on the 2020–2025 DGA. Documenting the descriptive data analyses used across previous cycles to inform the DGAC’s initial discussion may have improved the efficiency of the process to develop the 2020–2025 DGA.
Recommendation 6 Conclusions
The committee concluded that recommendation 6 was almost fully implemented through the development of a framework that standardized the terminology, thresholds, analytic methods, and interpretation related to nutrients of concern. The committee further concluded that the gaps in the implementation of recommendation 6 are unlikely to have substantially affected the content or perceived rigor of the 2020–2025 DGA.
Recommendation 7 Findings
The committee found that none of recommendation 7 was implemented as proposed. Full implementation of recommendation 7 was not expected to occur within this cycle. It is difficult to determine how initial partial implementation may have affected the 2020–2025 DGA because such implementation could have come in many different forms and to many different degrees.
Recommendation 7 Conclusions
The committee concludes that the full implementation of recommendation 7 could have significantly affected the rigor and integrity of the 2020–2025 DGA. Ultimately, the use of systems approaches and methods could substantially improve the rigor, integrity, and thus trustworthiness of future editions of DGA.
TASK 3 CROSS-CUTTING CONCLUSIONS
The committee concluded that additional non-federal expertise was not sought during the 2020–2025 DGA process. As a result, the objective of the 2017 report committee to achieve a more deliberative process has not yet been achieved.
Except for refinements made to the systematic review process and to standardizing the process for identifying nutrients of concern, the committee concluded that the proposed analytic and methodologic improvements to the DGA process had not yet been achieved. The DGA process still lacks an overall analytic framework.
TASK 3 OVERALL CONCLUSIONS
Overall, the committee concluded that it is not yet possible to evaluate the full potential of the proposed redesign of the DGA process to support its continued improvement. Given the expectations of the 2017 National Academies report committee, an important implication of these conclusions is that opportunities remain to improve the deliberative nature, transparency, rigor, and integrity of the DGA process as well as the ability of the DGA to address the needs of the diverse U.S. population.
The DGA are a foundational element of federal nutrition policy. The DGA process is time-restricted and complicated to administer. Creating the DGA is also intellectually complex, as it uses many types of data together to answer complex questions. Dietary intake is multidimensional, dynamic, and complex to measure, and the DGA process considers intake related to a range of health outcomes. Moreover, because much of the available studies of associations between dietary exposures and health outcomes are observational (as opposed to randomized controlled trials), development of dietary guidelines is challenging. The DGA may, at times, contain controversial recommendations. Such recommendations, or the ensuing debates, may threaten the perception by the public and scientific experts that the guidelines are trustworthy.
The process to develop the 2020–2025 DGA was extraordinary because the 2017 National Academies report was released after the process had begun. It was also the first DGA cycle to include chapters dedicated to guidelines for infants, toddlers, and pregnant and lactating persons, and a government shutdown delayed the beginning of the DGAC’s work. It is therefore understandable that the Departments were unable to implement all seven recommendations made by the 2017 report committee.
Approach by the Departments to Meet the 2017 Report Recommendations
The Departments communicated to the committee that their existing approaches “satisfy goals” or have accomplished by other means the recommendations of the 2017 National Academies report that they should create the DGPCG, TEPs, and the DGSAC. Moreover, they cite substantial barriers of cost, difficulty, and possible unintended consequences involved in creating these groups as additional reasons for not creating them.
The committee acknowledges that these barriers are real. All additions to a budget require justification and consideration of possible trade-offs, as would the addition of a new federal advisory committee. The committee further acknowledges that it is difficult to justify an additional expenditure toward reaching a goal when the entities requesting additional funds (i.e., the Departments) perceive the goal to have been substantially accomplished. Moreover, the 2017 National Academies report notes that other mechanisms may exist to address these recommendations.
Importantly, the Departments introduced and documented numerous changes to their procedures that addressed the values underlying some of the recommendations, even when they did not implement the recommendation as written. An example of this was structuring the DGAC and its work to serve the functions described in recommendation 1 for both the DGSAC and the TEPs. The Departments described many benefits to their approach.
Implementation of the Values from the 2017 National Academies Report
As noted above, the 2017 report committee identified five values that would improve the integrity of the process and lead to the development of credible and trustworthy guidelines. These values provided an additional lens through which the committee viewed its tasks, and are important because they were essential to the redesign of the process and are shared by the Departments.
To improve the transparency of the 2020–2025 DGA process, the Departments made important changes, such as increasing the use of public comments and improving the DietaryGuidelines.gov website to meet the needs of the public. Opportunities remain for further improvements in transparency, such as providing a public-facing, overall description of the framework for how the DGA process works, from conception to publication; a clear roadmap of who participates and how the various inputs are blended and harmonized, including an analytic framework; a
description of how public comments fit into the process; where external scientific input is engaged; and all the sources of information that go into the process. In the committee’s opinion, a more systematic, structured, and bidirectional communication process with experts, other stakeholders, and the public is required to reach the full benefit of the overall process redesign described in the 2017 National Academies report.
To promote diversity of experience and expertise, the Departments provided a federal-level, peer review of new systematic reviews. They also increased the size of the DGAC to include the external expertise needed to match the planned topics. Opportunities remain for further improvements in the involvement of external expertise. These include strategic planning and generation of topics for inclusion in the DGA, which includes creation of the DGPCG, or a group including experts external to the federal government, and relevant TEPs; peer review of the systematic reviews by experts external to the federal government, and the involvement of experts to bring systems-science approaches into the DGA process.
To support a deliberative process, the 2017 National Academies report committee recognized the need to obtain input from multiple stakeholders. It envisioned a deliberative process as “supporting adaptability, continuity, and continuous learning” and sought a process that “is adaptive to dynamic shifts in the system in which it operates.” Many federal agencies are already active participants in various aspects of the process to develop the DGA. The additional opportunities provided for public comment in the process to develop the 2020–2025 DGA were thought by the Departments to be an effective way of receiving input from several of these groups of stakeholders. However, in the committee’s opinion, providing input is not sufficient for a full “deliberative” process, which in common usage refers to a two-way discussion. This is why the 2017 National Academies report recommended that scientists from outside the federal government with subject-matter expertise be included in multiple roles in the redesigned process. Opportunities remain for further involvement of external scientific input.
To manage bias and conflicts of interest (COI), the Departments have policies that operate throughout the systematic review process and elsewhere in the production of the DGA. The Departments have policies that govern the COI of individual employees as well as for individuals involved in performing the systematic reviews. Opportunities remain for the Departments to manage the assessment of any relevant COI.
To adopt state-of-the-art processes and methods, NESR made numerous improvements to the processes and protocols used to create the systematic reviews. Opportunities remain to improve the process used for updating them and assessing the quality of evidence. In addition, the
framework developed to support the identification of nutrients of concern makes appropriate use of the available data and robust methods are used in related analyses of dietary data. Given that the Departments were unable to introduce the recommended systems-science approaches before the release of the 2020–2025 DGA, the opportunity to make these investments remains and first steps were taken in 2022. These investments are essential to support the ability of the DGA process to provide guidelines that make full use of the available data and address the diversity of dietary needs and preferences of the U.S. population.
The Committee’s Overall Perspective
This report provides an assessment of the implementation of the 2017 report recommendations in the spirit of making a strong process even better. Notably, several of the issues identified by the 2017 report committee still exist and will only become more challenging with each edition of the DGA. The committee acknowledges that implementing the higher-leverage recommendations is difficult and will require strategic planning by the Departments as well as staff effort and funding. Nonetheless, the committee regards such investments as crucial given that the DGA are foundational for nutrition-related federal programs and the nation’s health.
These investments in continuing to redesign the structure and process used to create the DGA can still be made and, in the committee’s opinion, are essential because the recommendations are expected to be effective and impactful when fully implemented. Moreover, as noted in the 2017 National Academies report, “Redesigning the process is an essential first step, but evaluation will also be needed to understand whether the public trusts the process and, in the long-term, whether adherence to the DGA recommendations actually improves.”
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