Summary¹

INTRODUCTION

In 1990, Congress passed the National Nutrition Monitoring and Related Research Act, which mandates that the U.S. Department of Agriculture (USDA) and the U.S. Department of Health and Human Services (HHS) publish the Dietary Guidelines for Americans (DGA) at least every 5 years. The law requires that these guidelines are based on the weight of current, published scientific and medical evidence. The DGA serve as the cornerstone of federal nutrition policy and nutrition education activities. They are a central source of guidance that the government uses to inform federal food and nutrition programs and initiatives and to tailor them to address program-specific audiences. The DGA also support the development of science-based nutrition education and consumer information for both the general public and special audiences that are used in the private sector.

To update the DGA, USDA and HHS jointly convene a Dietary Guidelines Advisory Committee (DGAC) to review the body of relevant evidence. In conducting its work, the DGAC examines the evidence in systematic reviews, food pattern modeling activities, and analysis of federal data sets; holds public meetings; and receives public comments. The DGAC’s work culminates with the submission of a DGAC Scientific Report to the secretaries of USDA and HHS. The report synthesizes the

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¹ This Summary does not include references. Citations for findings presented in the Summary appear in the subsequent chapters of the report.

current scientific evidence on topics relevant to the DGA and provides recommendations to the federal government for the development of the next edition of the DGA. After the DGAC Scientific Report is released, the public has opportunities to provide written comments and oral testimony to USDA and HHS on the report. As USDA and HHS develop the next edition of the DGA, they consider the current DGAC Scientific Report together with input from the federal agencies and public comments.

The release of the 2015 DGAC Scientific Report elicited a public response about reducing consumption of red and processed meat as well as the environmental sustainability of the U.S. diet. No recommendation to limit meat was included in the 2015–2020 DGA, and the term sustainability was excluded. The controversy that this situation created prompted Congress, in 2016, to appropriate funds to USDA and HHS for engagement with the National Academies of Sciences, Engineering, and Medicine (the National Academies) to conduct a comprehensive review of the process used to establish the DGA. This study published two reports in 2017 that provided recommendations for updating that process. In response to the 2017 National Academies recommendations, public feedback, best practices for reviewing nutrition science and developing guidance, and the departments’ desire to have a transparent, inclusive, and science-driven process, USDA and HHS implemented refinements to the process to develop the 2020 edition of the DGA (2020–2025 DGA). In December 2020, in section 796 of the Consolidated Appropriations Act, 2021, Congress mandated that USDA contract with the National Academies for a study to compare the process to develop the 2020–2025 DGA to the seven recommendations included in the 2017 National Academies report Redesigning the Process for Establishing the Dietary Guidelines for Americans.

Briefly, these 2017 recommendations were that the secretaries of USDA and HHS should

1. Redesign the DGA process to prioritize topics to be reviewed in each DGA cycle, and redistribute the current functions of the DGAC to three separate groups:
   1. A Dietary Guidelines Planning and Continuity Group (DGPCG) 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 (TEPs) to provide content and methodological consultation during the evaluation of the evidence; and
   3. A Dietary Guidelines Scientific Advisory Committee (DGSAC) to interpret the scientific evidence and draw conclusions.

2. Provide the public with a clear explanation when the DGA omit or accept only parts of conclusions from the scientific report.
3. Separate the roles of USDA Nutrition Evidence Library (NEL) staff and the DGSAC so that
   1. The NEL staff plan and conduct systematic reviews with input from technical expert panels, perform the risk-of-bias assessment of individual studies, and assist the DGSAC as needed;
   2. The NEL systematic reviews are externally peer reviewed before being made available for use by the DGSAC; and
   3. The DGSAC synthesizes and interprets the results of systematic reviews and draws conclusions about the entire body of evidence.
4. Ensure all 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.
5. Enhance food pattern modeling to better reflect the complex interactions involved, the variability in intakes, and the range of possible healthful diets.
6. Standardize the methods and criteria for establishing nutrients of concern.
7. Commission research and evaluate strategies to develop and implement systems approaches into the DGA. The selected strategies should then begin to be used to integrate systems mapping and modeling into the DGA process.

THE COMMITTEE’S TASK AND APPROACH

The task given to the Committee on Evaluating the Process to Develop the Dietary Guidelines for Americans, 2020–2025, is shown in Box S-1. The committee interpreted the task within the context of the background information for each recommendation in the 2017 National Academies report as well as the guiding principles articulated in that report. To approach its task, the committee developed key questions and gathered evidence on the responses to each recommendation, which was provided to the committee by USDA and HHS. This included the Scientific Report of the 2020 Dietary Guidelines Advisory Committee (2020 DGAC Scientific Report), the 2020–2025 DGA, website links, and documents provided in response to dialogue with the committee in two open sessions.

To inform its analysis in response to task 1, the committee developed a flowchart (see Figure S-1) to guide its assessment of the implementation of the seven 2017 National Academies recommendations. It then formulated a timeline for comparing the steps in the process to develop the 2015–2020 DGA and the 2020–2025 DGA with the 2017 National Academies recommendations.² This allowed the committee to identify when and where changes were made to existing steps in the process that were consistent with those recommendations.

The committee interpreted task 2 as a request to compare the “scientific studies used to establish the DGA” to the “most current and rigorous studies on this topic” (see Box S-1). The committee assessed the quality of the systematic review process used to select the studies included in the systematic reviews conducted for the 2020 DGAC Scientific Report. The committee developed a flowchart (see Figure S-2) to guide its assessment of the Nutrition Evidence Systematic Review (NESR) methodology that informed the search plan and inclusion and exclusion criteria. They then

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² This text, and similar text throughout the report, was modified after release of a prepublication version of the report to the sponsor to clarify references to the 2015–2020 DGA and 2020–2025 DGA, the development of which occurred between 2010–2015 and 2015–2020, respectively.

assessed whether the resulting body of evidence considered individuals with diet-related metabolic disease and included the most current and rigorous studies available.

The committee used its framework (described under task 1 above) together with information from the systematic review matrix summary (see Appendix C) to develop decision criteria relevant to task 2. The final decision criteria for specific recommendations germane to task 2 included

1. Evaluation of the appropriateness of the NESR approach to the search strategy, including date range, types of research included, and health status of individuals; and
2. Evaluation of the application of the search strategy to specific systematic review questions examined and published to inform the 2020 DGAC Scientific Report.

The decision criteria were then applied across the NESR systematic reviews used in the process to develop the 2020–2025 DGA to determine if and to what extent the committee’s compilation of identified practices were consistently implemented.³ The analyses carried out for task 1 and task 2 were used to formulate the committee’s findings and conclusions.

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³ This text was modified after release of a prepublication version of the report to the sponsor to clarify that the practices identified were the committee’s compilation of identified practices from selected authoritative groups, such as the Agency for Healthcare Research and Quality, the Institute of Medicine, and Cochrane. Further discussion of the committee’s methods can be found in Chapter 2. Similar clarifications have been made throughout the report.

PRIMARY FINDINGS AND CONCLUSIONS FOR TASK 1

The overarching goal of the 2017 National Academies recommendations was that the DGA process should be universally viewed, in particular by the general U.S. population, as valid, evidence based, and free of bias to the extent possible. The committee views these recommendations for the improvement of future versions of the DGA as a continuation of this ongoing process.

Recommendation 1 Findings

The committee focused on topic prioritization in its analysis of recommendation 1. It found that prioritizing topics for the process to develop the 2020–2025 DGA included topics developed as part of the Pregnancy and Birth to 24 Months (P/B-24) project as well as topics from prior DGA cycles. USDA and HHS prioritized the list of topics with input from other federal agencies as well as public comments before the DGAC was established. Following the public comment period, USDA and HHS released the final list of topics. It also found that the DGAC provided recommendations for topics to be considered by future advisory committees.

Recommendation 1a

Given the time frame for the process to develop the 2020–2025 DGA, recommendation 1a was issued too late in the process for implementation of the DGPCG as envisioned,⁴ which, if a federal advisory committee, requires approval under the Federal Advisory Committee Act.

Recommendation 1b

The committee found that instead of using TEPs, NESR conducted its systematic reviews directly with the 2020 DGAC. The committee’s analysis further revealed that the process used by USDA and HHS⁵ did not provide “consultation during the evidence evaluation” in the way described in the 2017 National Academies report, which proposed that the TEPs could assist with developing the systematic reviews.

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⁴ This text, and similar text throughout the report, was modified after release of a prepublication version of the report to the sponsor to clarify that a new charter would only be required if this DGPCG were a federal advisory committee.

⁵ This text, and similar text throughout the report, was modified after release of a prepublication version of the report to the sponsor to clarify that USDA and HHS jointly oversee the process to develop the Dietary Guidelines.

Recommendation 1c

The committee found that the 2017 National Academies recommendation to create the DGSAC, which also would have required action under FACA, occurred too late in the process to create the 2020–2025 DGA. Instead, the committee found that NESR and DGAC interpreted the scientific evidence and drew conclusions, but their efforts were not partitioned as described in the 2017 National Academies report. Recommendation 1⁶ was addressed by USDA and HHS redistributing some of the current functions of the DGAC to “federal nutrition scientists, existing federal committees, and NESR technical expert collaboratives.”

Recommendation 1 Conclusions

The committee concluded that prioritization of the topics for systematic reviews used in the 2020–2025 DGA was completed by federal staff, with input from public comments, before the DGAC began its deliberations. Furthermore, the reorganization and separation of the functions of the DGAC into three separate groups (DGCPG, DGSAC, and TEPs) was not implemented. Overall, the committee concluded that full implementation of recommendation 1 is essential if the guiding principles of the 2017 National Academies report are to be achieved. This would provide improved transparency and reduce possible conflicts of interest, which are needed to establish public trust in the DGA.

Recommendation 2 Findings

Recommendation 2 focused on transparency when the 2020 DGAC Scientific Report and the 2020–2025 DGA differ, as well as when USDA and HHS describe whether and why the DGA recommendations differed from those of the DGAC Scientific Report. The committee found that, for added sugars and alcohol, USDA and HHS provided a clear, transparent, and public account that the 2020–2025 DGA recommendations differed from the recommendations in the 2020 DGAC Scientific Report and why. Consistent with federal law, the agencies highlighted the “preponderance of scientific evidence” as their basis for decision making. The committee also found that further explanation of other differences was needed to enhance transparency.

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⁶ This text, and similar text throughout the report, was modified after release of a prepublication version of the report to the sponsor to clarify that the response by USDA/HHS of redistributing current functions of the DGAC was in response to all of recommendation 1 and not just 1c.

Recommendation 2 Conclusions

The committee concluded that though the 2020 DGAC Scientific Report and the 2020–2025 DGA differed in some instances, efforts were made by the secretaries of USDA and HHS to explain their reasons for these differences. However, these explanations were not fully transparent. Consistent identification and justification for all differences between the 2020 DGAC Scientific Report and the 2020–2025 DGA would further enhance transparency.

Recommendation 3 Findings

Recommendation 3 focused on separating the roles of the NESR staff and the DGSAC to ensure that the process follows best practice principles and a rigorous approach to the conduct of systematic reviews. The recommendation also outlined an approach to assigning tasks between the NESR staff and the DGSAC and emphasized the importance of peer review in the systematic review process.

Recommendation 3a

The committee found that TEPs were not implemented for any of the systematic reviews conducted following the release of the 2017 National Academies recommendations. This was because USDA and HHS did not have sufficient time and resources.

The committee found that the risk-of-bias assessments were conducted by NESR using appropriate standard tools for randomized controlled trials (RCTs), non-RCTs, and observational studies.

The 2017 National Academies recommendation that NESR assist the DGAC was implemented as the two groups worked collaboratively on many aspects of the systematic process outside of data extraction and assembling of the evidence tables. Although each step of the systematic review process is described in the 2020 DGAC Scientific Report, the committee found that the procedure does not provide for “a clear delineation of roles in order to minimize the introduction of bias and allow for an objective, evidence-based review” consistent with the 2017 National Academies recommendations.

Recommendation 3b

The committee found that each systematic review for the 2020–2025 DGA underwent a type of peer review, in contrast to previous DGA cycles in which no peer review was used. The committee noted that the NESR systematic review process began before the release of the 2017 National

Academies report. For systematic reviews conducted subsequently, NESR systematic reviews were reviewed internally by the federal government (HHS, USDA, Department of Defense, and Department of Veteran Affairs) and the results of the systematic reviews were posted on the USDA website.⁷

Recommendation 3c

Recommendation 3c specified that the DGSAC should synthesize and interpret the results of systematic reviews and draw conclusions about the entire body of evidence. The committee found that NESR contributed to organizing the synthesis of the evidence as well as drafting the text for the synthesis of the evidence before it was submitted to the DGAC. However, the committee was unable to determine whether the process was consistent across the systematic reviews. Furthermore, drafting of the conclusion statement and grading⁸ assignments appear to have been completed solely by the DGAC. It is also unclear whether this process was consistent across systematic reviews.

Recommendation 3 Conclusions

The committee concluded that the recommended use of TEPs was not implemented as specified in recommendation 3. The process of external peer review and the DGAC synthesizing and interpreting the results were only partially implemented. Moreover, a clear separation of function between NESR and the DGAC was not evident in the 2020 DGAC Scientific Report. This raises serious concerns about both transparency and conflict of interest. Further progress on this recommendation requires the formation of the three separate groups as described in recommendation 1.

Recommendation 4 Findings

Recommendation 4 focused on ensuring and enhancing the training of NESR staff, promoting continuous quality improvement, engaging

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⁷ Text in this paragraph, and similar text in the report, was modified after release of a prepublication version of the report to the sponsor to clarify that some systematic reviews—for example, the P/B-24 systematic reviews—were initiated before the release of the 2017 National Academies report and to correct a technical inaccuracy and clarify who was involved in the review process for the systematic reviews.

⁸ This text, and similar text throughout the report, was modified after release of a prepublication version of the report to the sponsor to clarify that NESR does not use the Grading of Recommendations Assessment, Development and Evaluation system for grading evidence.

external experts in a periodic review of the NESR review process, and introducing new advances in technology as they become available.

Recommendation 4a

Although the objectives of the 2017 National Academies report were posted on the NESR website, the committee found that this information did not describe a systematic approach intended to identify innovations in systematic reviews continuously. Overall, the committee was unable to assess the extent of the implementation of recommendation 4a.

Recommendation 4b

The committee found that, although USDA stated it routinely interacts with other agencies that conduct and use systematic reviews, this connection and the work completed by the Continuous Quality Advancement (CQA) program to refine NESR methods continually were unclear.

Recommendation 4c

Although updates to NESR practices occurred between the 2015–2020 DGA and 2020–2025 DGA cycles, it was unclear to the committee whether NESR training practices are sufficient to ensure updating of these practices. The committee found that further documentation of protocols and the accomplishments of USDA’s CQA program and the findings of their after-action report are needed to evaluate progress.

Recommendation 4d

The committee found that technological infrastructure changes between 2015 and 2020 included the shift to using the DistillerSR program. The committee found only limited evidence of other investments or requests for funding for technological infrastructure.

Recommendation 4 Conclusions

The committee concluded that the NESR systematic review processes were generally aligned with the committee-identified practices. Although the committee was unable to assess the effectiveness of the training fully, the NESR practices included recent improvements. Notably, there are opportunities to enhance the transparency and, thus, the perceived integrity of the systematic review through external peer review as well

as to improve the management of systematic review protocols. Updating these processes is also essential for ensuring the integrity of the DGA.

Recommendation 5 Findings

The aim of recommendation 5 is to enhance food pattern modeling to reflect the complex interactions involved, the variability in intakes, and the range of possible healthful diets. These include translating nutrient requirements into food combinations and estimating how well various eating patterns align with the Dietary Reference Intakes and inform the DGA.

The committee found that food pattern modeling was used to assess the ability to meet nutrient recommendations for each life stage through variations in USDA food patterns. The committee also found that refinements were made to account for variability in intakes and to address a range of possible healthy dietary patterns and that the 2020 DGAC Scientific Report explored the need to add or modify the USDA food patterns based on systematic reviews. The committee further found that the assumptions for the food pattern modeling were made transparent through the protocols and analytic frameworks posted online and discussed at DGAC meetings, as well as by the inclusion of key definitions. Lastly, however, the committee found that the analytic methods used for food pattern modeling in the process to develop the 2020–2025 DGA did not change substantially from the food pattern modeling methods used to create the 2015–2020 DGA.

Recommendation 5 Conclusions

The committee concluded that some enhancements were made to the food pattern modeling process, particularly to address variability in intakes. However, the analytic methods used in the food modeling process did not change from the prior DGA cycle and thus partial implementation of this recommendation presents serious concerns about adequate rigor of the guidelines given the diversity of food patterns in the U.S. population. Moreover, this is an important missed opportunity to create a better informed and more useful product.

Recommendation 6 Findings

Recommendation 6 states that the methods and criteria for establishing nutrients of concern, which are based on the prevalence of inadequate and excess intakes in the population, should be standardized. The 2017 National Academies report noted that “consistency would facilitate com-

parisons of descriptive data analyses over time, benefiting practitioners, consumers, and the food sector.”

The committee found that there were some enhancements to the process to develop the 2020–2025 DGA. Specifically, the 2020 DGAC Scientific Report and a later peer-reviewed publication documented a framework that standardized the terminology,⁹ thresholds, analytic methods, and interpretation related to nutrients or food components (NFCs) of public health relevance. The committee further found that the DGAC, working with federal partners, initiated the identification of potential NFCs of public health concern before examining data. However, the federal agencies have not publicly documented the descriptive data analyses commonly used across previous DGACs. Lastly, the committee found that, with regard to transparency, a protocol was developed with the 2020 DGAC and posted before any data were reviewed and synthesized.

Recommendation 6 Conclusions

The 2020 DGAC Scientific Report and a later peer-reviewed publication documented a framework for standardizing the terminology, thresholds, analytic methods, and interpretation related to nutrients of concern, building on the approach used by the 2015 DGAC and proposing an approach for future committees. The 2020–2025 DGA initiated data analyses early in the process and showed greater transparency. Therefore, the committee concluded that recommendation 6 was nearly completely implemented with only minor remaining concerns.

Recommendation 7 Findings

Recommendation 7 focuses on integrating more systems approaches into the DGA process. It is overarching and crosscutting, because multiple complex systems affect diets, dietary behaviors, and dietary intake. The 2017 National Academies report acknowledged that it may require time for systems approaches to be incorporated into the DGA process and that this process could be gradual and iterative. However, the 2017 National Academies report also suggested starting as soon as possible to integrate systems approaches and methods into the DGA process. Although the DGAC, USDA, and HHS acknowledged the importance of the 2017 National Academies recommendation to integrate systems science into

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⁹ This text, and similar text throughout the report, was modified after release of a prepublication version of the report to the sponsor to clarify that the framework and method described was first documented in the 2020 DGAC Scientific Report and later documented in a peer-reviewed journal article.

the nutrition evidence base and the DGAC processes, the committee found no discernable planning or implementation activities other than requests for additional funding.

Recommendation 7 Conclusions

The committee concluded that recommendation 7 was not implemented. The committee notes that steps need to be initiated soon, as the implementation of recommendation 7 is critical to the expansion of the DGA for developing guidelines that capture the heterogeneity of the American population.

OVERARCHING CONCLUSIONS FOR TASK 1

Overall, the committee found that USDA and HHS took steps toward implementing the 2017 National Academies recommendations. However, the extent of implementation was not uniform within and across these recommendations. The changes that have been made have focused on those 2017 National Academies recommendations and subcomponents that could most readily be implemented from the time of the release of the report to that of the DGA. Further changes will be needed during the preparation of the 2025–2030 DGA to implement the seven 2017 National Academies recommendations completely.

PRIMARY FINDINGS AND CONCLUSIONS FOR TASK 2

The second task of the committee was to respond to the question: Did the criteria for including scientific studies in the evidence base used to inform the DGA ensure that the evidence base was current, rigorous, and generalizable or applicable to public health nutrition guidance?

Findings for Committee-Identified Practices

The 2017 National Academies report recommended that the procedure for using existing DGAC systematic reviews and updating them should incorporate advances in systematic review methodology using a multi-pronged approach. This includes employing an established method for ongoing surveillance to identify and evaluate the research as it is being published, along with the determination of what types of updates may be needed before including existing systematic reviews.

The committee found that the systematic review process identified was unclear about when the systematic review protocol was “approved” and when subsequent modifications were made. Thus, the committee was

unable to determine the effect of protocol changes on the identification and synthesis of evidence.

For the process to develop the NESR search protocols, the committee found that NESR made improvements relative to prior editions of the DGA, which included posting protocols and modifications to protocols for public comment. The committee found that the updated process enhanced transparency. At the stage of a priori review of the systematic review protocol, the committee-identified practice is to have a peer review completed by reviewers with expertise in the content area of the review and systematic review methodology. It is, however, unclear if what NESR did was equivalent to the committee-identified practice. The committee was unable to determine if any of the comments from the new peer review after the systematic reviews addressed the search plans. The committee was also unable to compare the earlier versions of the protocol to the final. Therefore, the committee was unable to assess if changes made in response to the peer-review affected the body of evidence in the systematic review.

For the design and conduct of systematic reviews, the committee found that the process of establishing systematic review questions, the analytical framework, search strategy, and examination of how closely the existing systematic review mirrored their current question was in accord with committee-identified practices. However, the committee was unable to discern which systematic reviews included updates and, if so, which prior systematic reviews were updated for the cycle to develop the 2020–2025 DGA. The committee found that the current methodology for deciding if an existing systematic review needed a full update appeared to be based only on conclusion statements that had been rated with lower grades of evidence. The system for ongoing surveillance of published research recommended in the 2017 National Academies report, not yet implemented, would provide invaluable input on whether to update existing systematic reviews. These deviations from committee-identified practices decrease the transparency and rigor of the decision-making process.

Conclusions for Committee-Identified Practices

The committee concluded that the process to identify questions and create analytical frameworks was implemented. The addition of posting portions of the search protocol for public comment enhanced transparency. The internal peer review of the search strategy and terms by a second NESR librarian enhanced the rigor of the process. The addition of agency-level peer review after the systematic review was completed also enhanced perceived integrity. However, the committee was unable

to determine whether these processes together would be equivalent to committee-identified practices. The lack of consistent and thorough documentation of the protocol modifications, which led to changes in the studies selected for review, decreases transparency and increases the potential for bias. Similarly, the lack of decision guides for determining the need for and type of updates contributed to inconsistent documentation of how existing systematic reviews were updated. The absence of the ongoing surveillance system for published research recommended in the 2017 National Academies report makes it difficult to determine the need for and type of updates to be done. Taken together, these remaining obstacles compromise the integrity, transparency, and deliberative process, and leave open the possibility for the introduction of bias into the NESR systematic review process.

Findings for Search Plan Inclusion and Exclusion Criteria

For NESR’s systematic review search strategy and inclusion and exclusion criteria, the committee identified two overall search-strategy components that would affect the generalizability of the body of evidence for creating public health nutrition guidance. By excluding secondary-prevention interventions and studies from countries not classified with a high Human Development Index (HDI), the body of evidence may be limited.

The committee’s assessment of the DGAC methodology found that the NESR search strategies were tailored to match some aspects of the questions and analytical framework. The committee further found that how the general search strategy for addressing chronic diseases was tailored varied by search question, but was unable to find specific justification for these modifications. The committee noted that the modifications of the search strategy often supported the goal of including rather than excluding individuals with chronic health conditions or risk factors for such conditions. The committee also found that the body of evidence was current up to the date of the systematic review search. Finally, the committee found that the NESR systematic reviews were based on the most rigorous study designs available. There were few exceptions and, in these cases, the additional types of research designs included were appropriate to the questions being addressed.

Conclusions for Search Plan Inclusion and Exclusion Criteria

The committee concluded that the overall search strategy was well described and justified and was generally implemented as proposed in the 2017 National Academies report. It also concluded that, in many cases,

NESR systematic reviews were tailored to include populations with some chronic health conditions, such as obesity.

The committee further concluded that the process of establishing systematic review questions, the analytical framework, and search strategy and examining how closely the existing systematic review mirrored the current question was a sound approach. However, the committee was unable to discern which systematic reviews included updates and, if so, which prior systematic reviews were updated for the cycle to produce the 2020–2025 DGA.

The committee concluded that the appropriate date range was implemented, the evidence base included in the systematic reviews was current, and the appropriate study designs for the specific questions were implemented. Lastly, the committee concluded that the exclusion of prevention-intervention research and research from countries not classified with a high HDI may reduce the generalizability of the outcomes of the systematic reviews to the U.S. population.

OVERARCHING CONCLUSIONS FOR TASK 2

The committee concluded that the overall search strategy was well described and justified and was generally implemented as proposed in the 2017 National Academies report. The methodology for new systematic reviews was more carefully developed than the methodology for using existing systematic reviews. The absence of the recommended ongoing surveillance system for published research hampers the ability to determine the need for and type of updates that are required. Finally, the exclusion of prevention-intervention research and research from countries not classified with a high HDI may reduce the generalizability of the outcomes of the systematic reviews to the U.S. population.

CONCLUDING REMARKS

From the committee’s analysis, findings, and conclusions in this midcourse report, the following overarching conclusions have been reached.

First, the committee concluded that significant progress has been made toward the implementation of these recommendations, although progress has been uneven. The 2017 National Academies recommendations with the longest lead time and/or the greatest bureaucratic hurdles were least likely to have been implemented.

Second, the committee recognized that implementation of all seven 2017 National Academies recommendations would take time, resources, training, and perhaps some reorganization of functions within the agencies.

Third, the recommendations with the least progress toward implementation are those that are most necessary to address the principles of the 2017 National Academies report.

Fourth, the committee acknowledged that the timing of the release of the 2017 National Academies report within the 5-year DGA cycle was a key factor in the ability of the federal agencies to implement some of the recommendations. The timing was problematic for the creation of the two new recommended committees.

Fifth, the recommendations to strengthen food pattern modeling and to introduce systems-science approaches to the DGA process were difficult to implement because of challenges with lead time. Both these recommendations will require investments in specially qualified personnel and new scientific approaches.

Sixth, the committee concluded that the overall search strategy for the systematic reviews was well described and justified and was generally implemented as proposed in the 2017 National Academies report. Expanding the generalizability of these systematic reviews to all Americans remains a challenge.

Finally, the committee identified many instances of partial implementation of the recommendations of the 2017 National Academies report. Some of these were minor concerns. Many other concerns might, individually, seem minor but represent a more substantial concern when considered together. Moreover, the combined effect of recommendations for which there were substantial concerns with those that were not implemented represents a continuing risk to the integrity of the DGA process.

It remains the case that the processes used to produce DGA must be based on strong bodies of evidence, careful decision making, and communications about the DGA process to be trusted by the scientific community, health professionals, and the public.