Assessing the Potential Implications of Fully Implementing the 2017 Recommendations to Redesign the Process to Establish the Dietary Guidelines for Americans: Committee Findings and Conclusions
This chapter describes the findings and conclusions of the Committee on Evaluating the Process to Develop the Dietary Guidelines for Americans, 2020–2025 (2020–2025 DGA) for Task 3, which was to assess how full implementation of the seven recommendations in the report Redesigning the Process for Establishing the Dietary Guidelines for Americans (2017 National Academies report) (NASEM, 2017a) would have affected the timeline, cost, and integrity of the process used to create the 2020–2025 DGA (USDA/HHS, 2020).
The 2017 National Academies report included a set of seven recommendations that, when implemented together, were designed to enhance the process to create the DGA by “improving transparency, promote diversity of expertise and experience, support a deliberative process, promote independence in decision making, and strengthen scientific rigor” (NASEM, 2017a).
“A principal finding” of the 2017 National Academies report was that the current 5-year cycle of the process used to create the DGA would benefit from greater continuity and efficiency (NASEM, 2017a). This would “not only provide the opportunity for a more thorough evaluation of the science, but also allow the DGA process to become more agile,
flexible, and effective—and address more topics of interest to the public” (NASEM, 2017a).
The first recommendation, which is a “central recommendation” in the 2017 National Academies report, was to “allow for more focused and tailored groups of experts to undertake each of the functions [of the DGAC] by dividing them among several groups during the 5-year cycle” (NASEM, 2017a). Not only would this reduce the high level of effort required by the DGAC during its 2-year life span, but it would also “provide many more opportunities for stakeholder and public participation, and thus serve to insert greater transparency into the process” (NASEM, 2017a).
The 2017 National Academies report also noted that using the whole 5-year cycle would provide opportunities for improving transparency. Improved transparency was especially needed when there was a discrepancy between the DGAC Scientific Report conclusions and the DGA recommendations, as occurred in the 2015–2020 DGA (NASEM, 2017a). This situation led to the second recommendation in the 2017 National Academies report (NASEM, 2017a).
Given the importance of scientific rigor to the integrity of the DGA, the 2017 report committee thought that it was “critical that the methods used to inform the DGA be validated and appropriate to the questions being asked” (NASEM, 2017a). The 2017 report committee also found that the methods used in the DGA process were indeed appropriate, but they could be strengthened in ways that are enumerated through recommendations 3 through 7 (NASEM, 2017a). The 2017 report committee recommended “strengthening and adopting appropriate and strategic methodologies to align with current best practices,” related to systematic reviews, food pattern modeling, descriptive data analyses, and the integration of systems approaches (NASEM, 2017a). The 2017 National Academies report also noted that “DGACs have yet to use an analytic framework to guide topic selection, synthesis, and interpretation of evidence on topics of the relationships of diet, health, and chronic disease” (NASEM, 2017a). The identified needs for the use of improved methodologies and an analytic framework are critical as the DGA have recently expanded to cover “all Americans”—not just those who are healthy—as well as several population subgroups for the first time, namely children under 2 years of age as well as individuals who are pregnant and lactating.
The 2017 report committee envisioned that implementing these seven recommendations “would contribute to a higher degree of integrity and thus enhance the trustworthiness of the process to develop the DGA” (NASEM, 2017a). It is noteworthy that although the 2017 National Academies report provided a sequence of activities that covered the whole
For each recommendation in the 2017 report, relative to the 2020–2025 DGA process, the committee provides background information, evidence of the Departments’ implementation, evidence of constraints to implementation (namely, timeline and cost as described in Chapter 3), findings with respect to the committee’s assessment of whether and to what extent implementation occurred, and findings with respect to the expected effect of full implementation on the DGA. The chapter ends with the committee’s conclusions for each recommendation, its conclusions from considering two or more recommendations together, and its overall conclusions for Task 3.
The evidence, findings, and conclusions presented here for Task 3 are inclusive of and supersede those for Task 1 as presented in the committee’s report Evaluating the Process to Develop the Dietary Guidelines for Americans, 2020–2025: A Midcourse Report (NASEM, 2022a). This is because these two tasks overlap and the material presented here reflects new information gathered and analyses conducted since the midcourse report was prepared.
The committee views recommendation 1 from the 2017 National Academies report as a key, cross-cutting recommendation for redesigning the process for establishing the Dietary Guidelines for Americans. That recommendation proposed a redesign of the DGA process to prioritize topics to be reviewed in each cycle and to redistribute the current functions of the DGAC into three new groups (Box 4-1). In this recommendation, the 2017 report committee incorporated aspects of many of the critical elements of its proposed redesign.
The 2017 report committee suggested that the 5-year DGA cycle time could “be leveraged more effectively by redistributing the tasks of the Dietary Guidelines Advisory Committee (DGAC) to other entities,” but that doing so would add “additional components and potentially more cost to the overall process” (NASEM, 2017a). Nonetheless, the 2017 report committee concluded that such redistribution would enable more targeted expertise to
be dedicated to completing a specific task, resulting in higher-quality inputs into the synthesis of evidence, and more time for deliberations,
stakeholder engagement, and transparency-related activities…[and] also permits much of the context setting and evidence development to be accomplished early on in the process. (NASEM, 2017a)
The current committee recognizes that there were constraints to fully implementing recommendation 1 during the process to create the 2020–2025 DGA, such as the timing of the 2017 report’s publication relative to the then-ongoing DGA cycle (i.e., the 2017 report was published more than a year after the 2020–2025 DGA process had begun), the expected financial costs to implement parts of the recommendation, and the need for action at the highest levels of the Departments.
Recommendation 1 was directed to the Secretaries of USDA and HHS because the new committee it would establish—the Dietary Guidelines Planning and Continuity Group (DGPCG)—would be subject to the Federal Advisory Committees Act (FACA) (NASEM, 2017a). Recommendation 1 would also require revising the charter of the DGAC, which is subject to the FACA, to transition it into a new committee called the Dietary Guidelines Scientific Advisory Committee (DGSAC). Creating these two new committees would incur both one-time and continuing costs, and result in redistributing federal staff activities across the entire 5-year DGA cycle, which may require changes in the timing of staff work on the DGA.
Evidence of Implementation
Recommendation 1a was to create the 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. The DGPCG was not created as part of the process to develop the 2020–2025 DGA, which meant there was no process (or group) created for monitoring and curating the scientific evidence. Prioritizing topics for inclusion in the systematic reviews and providing strategic planning across cycles continued to be provided by federal staff members. According to USDA and HHS:
USDA’s Center for Nutrition Policy and Promotion [CNPP] and HHS’s Office of Disease Prevention and Health Promotion [ODPHP] have staff who continuously support the Dietary Guidelines process and plan for future editions. These staff work with other Federal nutrition scientists in standing committees, including the Interagency Committee on Human Research Subcommittee on Dietary Guidance and the Dietary Guidance Review Committee to identify and prioritize topics for inclusion in the Dietary Guidelines process, and to provide strategic planning support across Dietary Guidelines cycles. (DGA, 2021)
The Departments further noted that:
The list of topics and questions was informed by experts from across the Federal government including scientists, nutritionists, and program specialists from USDA, HHS, the Department of Veterans Affairs, and the Department of Defense. To finalize the list, public and agency comments were requested and considered based on the predetermined and publicly stated criteria listed online and in the Federal Register notice. (DGA, 2021)
The Departments explained that part of the rationale for relying on government experts to prioritize topics to be reviewed in the 2020–2025 DGA is that the two Departments consider the federal programs to be the “primary end users of the Dietary Guidelines” (NASEM, 2022b).
Monitoring of evidence was not conducted during the process to develop the 2020–2025 DGA. USDA and HHS explained that to conduct such monitoring, the Departments needed to have questions with corresponding monitoring protocols, which were not available at the time that the 2017 report was received (NASEM, 2022b).
The Departments also identified several benefits of their approach to the 2020–2025 DGA. These were that:
[it] supports [the] goals of [this recommendation] (e.g. diversity of expertise and separation of roles); [the] public comments process [was] successful and well-received; CNPP/ODPHP staff are uniquely positioned to support strategic planning (e.g. monitor nutrition science and international guidance, lead [the] ICHNR [(Interagency Committee on Human Nutrition Research) subcommittee] on [the DGA], support implementation of [the] DGA). (NASEM, 2022b)
Recommendation 1b was to create TEPs to provide content and methodological consultation during evaluation of the evidence. Although explicitly constituted TEPs were not created as part of the process to develop the 2020–2025 DGA, USDA and HHS noted that this role was played by “DGAC subcommittees, with review and input from the full [DGAC] committee” (NASEM, 2022b). They also identified other entities that provided content and methodological consultation during evaluation of the evidence, including “Federal [subject-matter experts], as needed; previous DGACs and TECs [Technical Expert Collaboratives] (by using/updating their existing NESR [Nutrition Evidence Systematic Review] reviews); USDA/HHS food pattern modeling and data teams, [and] public comments.”
The Departments identified the benefits of their approach to the 2020–2025 DGA, noting that it:
ensures that … the DGAC’s review and integration of the evidence to advise the government is really an independent work of an external expert committee, which we think enhances its trustworthiness. [This] then also reduces that perception of bias or conflict of interest, but at the same time [the DGAC is] able to leverage our trained and qualified NESR team to really help execute that big scope of work that has to be done in such a tight timeline. (NASEM, 2022b)
The Departments also stated that this approach promotes diversity by “considering input from federal SMEs [subject-matter experts]… input from previous advisory committees, our TECs [technical expert collaboratives]… and public comments” in addition to allowing “NESR to focus on conducting CQA [Continuous Quality Advancement] and assessing research availability” (NASEM, 2022b).
Recommendation 1c was to create the DGSAC to interpret the scientific evidence and draw conclusions. The DGSAC was not created as part
of the process to develop the 2020–2025 DGA, therefore the functions of the DGAC were not redistributed as proposed in recommendation 1.
The Departments stated that they:
provided substantial staff and contractor support before and during the process to support the Advisory Committee’s [DGAC’s] scientific review. This support allowed the Advisory Committee to focus on: (1) drawing conclusions and (2) integrating the evidence to provide advice to the Departments. While staff supported analyses, the conclusions presented in the Advisory Committee’s report are those of the Advisory Committee. Additionally, the Departments requested that the Advisory Committee provide advice to the agencies in the “summary” sections of each of the science-based chapters of its report. Also, for the first time in the Dietary Guidelines process, the Advisory Committee’s final meeting focused on its draft report. This meeting allowed for discussion and deliberation by the full Advisory Committee before submitting its report to the Secretaries of USDA and HHS. In these ways, the Departments supported the separation of roles and responsibilities to allow the Advisory Committee to focus on drawing conclusions and preparing advice for the Departments. (DGA, 2021)
The Departments identified the benefits of their approach to the 2020–2025 DGA, stating that they believe it accomplished the separation of roles of the DGAC roles from those of the federal staff and contractors had “quite a bit more transparency and public deliberation and public participation than we would be able to accomplish with TEPs and the DGSAC as defined in the 2017 report” (NASEM, 2022b).
Evidence of Constraints to Implementation
The implementation of recommendation 1 was constrained by timing, bureaucratic hurdles, and financial costs. The 2017 National Academies report was delivered to USDA in July 2017, the middle of the second year of the 5-year DGA cycle. At this point, it was too late to create an explicitly constituted TEP to conduct advance preparation for the DGAC, create a new FACA-governed committee, and re-charter an existing FACA-governed committee (see Chapter 2, Appendix B) because the FACA process takes several months to 1 year (Appendix D).
It is noteworthy that FACA-regulated committees “can only be created when they are essential to the performance of a duty or responsibility conveyed upon the Executive Branch by law or Presidential Directive” (GSA, 2019). Moreover, there are additional constraints involved in re-chartering or creating a committee subject to FACA approval, which includes agency ceilings on their number, a concern in both Departments
(NASEM, 2022b). The 2017 report committee considered three options for creating the DGPCG: (1) as a federal advisory committee subject to the FACA regulations with its charter renewed every 2 years, (2) as a federal group consisting of both federal and non-federal members but not governed by FACA, which could meet continually but not issue consensus recommendations to the secretaries of USDA and HHS, and (3) as a group convened by a non-governmental organization, which would neither be subject to FACA regulations but also not as influential as the first option (NASEM, 2017a). Given these options, the 2017 report committee believed that “establishing the DGPCG as a federal advisory committee to be the most likely option to yield a trustworthy, dependable evaluation of the science, without causing undue burden on any particular agency” (NASEM, 2017a). Federal agencies can obtain information or advice from external subject-matter experts in a variety of other avenues (Personal communication, GAO, July 20, 2022), but such avenues are ad hoc and could not provide the continuous advice envisioned of the DGPCG, nor do they provide an opportunity for deliberation between external subject-matter experts and the Departments.
The Departments identified “staff availability, limited transparency, and timeliness of work” as barriers to implementation of the TEPs (Appendix D). Specifically, additional staff would be needed to support the activities of a TEP; TEPs are not subject to FACA requirements for transparency; and the systematic reviews that they might support would be undertaken sooner than they are at present, rendering them less timely by the time the DGA are published. These views consider only one possible use of a TEP—to share the work of the current DGAC with the proposed DGSAC. In the committee’s view, similar to the view of the 2017 report committee, TEPs could be used to support “the scientific needs of the [DGA] process” in numerous other ways that do not have these drawbacks (NASEM, 2017a). USDA emphasized to the committee that the creation of the DGA is an “unfunded mandate,” which requires USDA and HHS to seek funding for each individual DGA cycle (Appendix D). Therefore, the additional staff time and funding needed to cover the costs of recruiting and supporting the DGPCG, as well as any costs associated with rechartering the DGAC to create the DGSAC, were unavailable at the time recommendation 1 was published. The Departments elaborated that they have a budget ceiling for federal advisory committees:
We can only spend a certain amount of money on federal advisory committees. … Even if we had the funds we need to have conversations to see if USDA or HHS [could] actually implement another federal advisory committee. It is difficult to justify [creating another federal advisory com-
mittee] if we are able to accomplish the goals in a forum without a federal advisory committee. (NASEM, 2022b)
The Departments estimated that the cost of administering the DGPCG and DGSAC would each be similar to that of the current DGAC, which they expected would double the cost of this aspect of the DGA process, which is already a major driver of the process’s overall costs (Appendix D). USDA and HHS also identified the “communications challenge of changing it from the dietary guidelines advisory committee to the dietary guidelines scientific advisory committee. We’re concerned that it gives an implication that is not intended” as a barrier to the implementation of recommendation 1c (NASEM, 2022b).
The committee found that the three components of recommendation 1 were not implemented as proposed in the 2017 National Academies report. As a result, the functions of the DGAC were not redistributed to three new groups as proposed, nor was a process for monitoring and curating scientific evidence established. Nonetheless, USDA and HHS made changes described above to redistribute some of the functions of the DGAC, consistent with the intent of recommendation 1 for the DGAC to focus on interpretation and integration of data.
A central theme of the 2017 National Academies report was improving the deliberative process to create the DGA. During the 2020–2025 DGA process, the only substantial input from scientific experts external to the federal government was provided by the members of the DGAC. The committee found that such external expert input is not currently available in the strategic planning process or the prioritization of systematic reviews because the committee does not view public comments as providing input equivalent to that obtained from greater engagement with external subject-matter experts.
The committee found that there were barriers related to the timing and cost of implementing this recommendation during the process to develop the 2020–2025 DGA, as well as other, non-trivial barriers to creating an additional federal advisory committee (i.e., the DGPCG). However, the alternative to creating the DGPCG considered by the 2017 report committee and discussed by USDA and HHS (Appendix D) would provide input that is neither continuous nor deliberative. As a result, new options are needed for developing a process that engages subject-matter experts who are external to the federal government, can operate continuously, and provide a forum for deliberation.
In addition, although the federal agencies are important—and essential—end users of the DGA, they are not the only important or essential users. The legislation1 that created the DGA mandates that they contain “nutritional and dietary information and guidelines for the general public” (USDA/HHS, n.d.).2 Reaching the general public also calls for the support of many different kinds of scientists and healthcare providers. Thus, the committee finds it essential that strategic planning for the DGA and prioritization of the systematic reviews include the perspective of experts who are external to the federal government.
For recommendation 1a, the committee found that if there had been no constraints, the process to create the DGPCG could have begun during the 2020–2025 DGA process and been fully in place by the beginning of the 2025–2030 DGA process. For recommendation 1b, the committee found that it was too late for the TEPs to provide advance services for the DGAC but it was neither too late nor too costly to create TEPs to provide additional scientific expertise to other elements of the process to develop the 2020–2025 DGA, should such expertise had been needed. For recommendation 1c, the committee found that the cost of administering two FACA-governed committees would be about twice that of administering the DGAC, and that FACA-governed committees are subject to additional constraints (e.g., the need for a strong justification to create a new federal advisory committee and agency-level ceilings on the number of such committees permitted to operate at a given time).
Expected Effect of Full Implementation on the 2020–2025 DGA
The committee could not ascertain how the full implementation of recommendation 1 would have affected the process to create the 2020–2025 DGA. The committee did not have information to determine whether different topics would have been chosen for review if a DGPCG had been created. But if it had been created, strategic planning for the 2025–2030 DGA could have begun with the additional insights of scientific experts who are external to the federal government.
The committee found that if TEPs had been needed, they could have been created for uses other than advance preparation for the DGAC. However, the committee had no information to determine if the DGAC
1 National Nutrition Monitoring and Related Research Act of 1990, Public Law 101-445, 101st Cong. (October 22, 1990). https://www.govinfo.gov/content/pkg/STATUTE-104/pdf/STATUTE-104-Pg1034.pdf
2 National Nutrition Monitoring and Related Research Act of 1990, Public Law 101-445, 101st Cong. (October 22, 1990). https://www.govinfo.gov/content/pkg/STATUTE-104/pdf/STATUTE-104-Pg1034.pdf
would have reached different findings or conclusions if TEPs had been used in this part of the process.
Finally, the committee did not have information to determine if a DGSAC would have evaluated the evidence differently and come to different conclusions than those developed for the 2020 DGAC Scientific Report, had key functions of the DGAC been redistributed between TEPs and the DGSAC.
The intent of recommendation 2 was to ensure that the public is provided information at the time of the DGA public release to explain any deviations between the conclusions in the DGAC Scientific Report and the recommendations in the DGA (Box 4-2). Responsibility for the implementation of this recommendation lies with the Secretaries of USDA and HHS, per the 2017 National Academies report, as they are the designated recipients of the DGAC Scientific Report and the issuers of the DGA.
Before the 2017 National Academies report, stakeholders (e.g., the public, the scientific community, and Congress) expressed concern about the differences between the DGAC Scientific Report and the DGA. The controversies surrounding the 2015 DGAC Scientific Report and the 2015–2020 DGA are examples of this (see Chapters 1 and 2). The committee acknowledges that some controversy is inevitable given the differences in interests and priorities of stakeholder groups, but the implementation of recommendation 2 is one way to promote transparency and enhance the trustworthiness of the DGA. The 2017 report committee noted:
To enhance the integrity of the process, every effort needs to be made to ensure that the DGA Policy Report is transparent about what decisions were made about the DGSAC’s conclusions, and the secretaries should explain why any deviations exist. (NASEM, 2017a)
Based on the suggestion from the 2017 report committee that deviations between the two reports should be explained, 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.
Evidence of Implementation
Nearly all of the recommendations in the 2020–2025 DGA align with the 2020 DGAC Scientific Report’s conclusions (USDA/HHS, 2020; DGAC, 2020). However, USDA and HHS clearly and publicly acknowledged that the DGA did not include all of the DGAC’s advice related to added sugars and alcohol intake:
The Dietary Guidelines emphasizes the importance of limiting intakes of added sugars and alcoholic beverages, but [it] does not include the changes to quantitative limits recommended by the Committee [DGAC]. … There was not a preponderance of evidence in the Committee’s review of studies since the 2015–2020 edition to substantiate changes to the quantitative limits for either added sugars or alcohol. (DGA, n.d.)
The Departments interpreted recommendation 2 to cover instances when the DGA omitted or accepted only parts of conclusions from the DGAC Scientific Report (NASEM, 2022b). The committee’s midcourse report highlighted a few additional areas where discrepancies might be interpreted as existing between the 2020 DGAC Scientific Report and the 2020–2025 DGA beyond intakes of added sugars and alcohol (NASEM, 2022a). These areas include instances where the DGA made a recommendation on a topic but the DGAC Scientific Report did not (e.g., vitamin and mineral supplementation during pregnancy; use of donor breast milk), areas where the DGAC Scientific Report, but not the DGA, cited limited evidence in support of advice (e.g., omega-3 fatty acid supplements in pregnancy), and instances where the DGAC Scientific Report made a recommendation that did not appear to be clearly presented in the DGA (e.g., choice of fish that is high in omega-3 fatty acids at multiple life stages). Hess (2022) noted an additional area of difference between the 2020 DGAC Scientific Report and the 2020–2025 DGA, which was whether vegan diets can be sufficient for toddlers.
Evidence of Constraints to Implementation
The committee did not identify any evidence of significant constraints to implementation of recommendation 2. The 2020–2025 DGA were accompanied by an explanation for two differences between the DGA and the DGAC Scientific Report (DGA, n.d.). Federal staff on the Dietary Guidelines writing team would need to do some additional work to identify and justify the remaining differences (NASEM, 2022b). As a result, the committee estimates that the constraints to fully implement this recommendation would be relatively minimal.
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.
For the process to develop the 2020–2025 DGA, no criteria were provided by the Departments for deciding whether DGAC Scientific Report and DGA recommendations were sufficiently different to require a public explanation. Moreover, no detailed description of “preponderance of scientific evidence” was provided. Additional differences (i.e., beyond the text of the recommendation that refers to “omit or select only parts of conclusions”) between the DGAC Scientific Report and the DGA other than alcohol and added sugars were not highlighted or explained.
Expected Effect of Full Implementation on the 2020–2025 DGA
The committee concluded that 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, particularly because such explanations are provided after the establishment of the DGA.
The committee interpreted recommendation 3 (Box 4-3) as guidance to separate the roles of NESR (formerly Nutrition Evidence Library [NEL]) and the proposed DGSAC, the new committee that would have a more focused role than the current DGAC. The committee also interpreted this recommendation as a call for the NESR systematic reviews to be conducted with input from experts (i.e., in the form of TEPs as needed) and peer-reviewed by experts who are external to the federal government.
The 2017 report committee had a specific vision about the roles of the TEPs, NEL (now NESR), and the proposed DGSAC. For recommendation 3a, the 2017 report committee envisioned that TEP members would be subject-matter experts in the specific research method being considered and that multiple TEPs may be needed, but that they would not need to convene in person (NASEM, 2017a). For recommendation 3b, the 2017 report committee emphasized the importance of external peer review in the systematic review process before submission to the DGSAC and suggested that:
the NEL explore existing infrastructures, such as collaborating with nutrition-focused scientific journals, to facilitate implementation of a peer-review process. (NASEM, 2017a)
For recommendation 3c, the 2017 report committee specified the role of the proposed DGSAC to
be focused on integrating results derived from multiple types of analyses (e.g., original systematic reviews; existing systematic reviews, meta-analyses, and reports; food pattern modeling; and descriptive data analyses) to develop conclusions about the totality of evidence relating diet and health. (NASEM, 2017a)
Recommendation 3 was directed to the Secretaries of USDA and HHS, who would be responsible for full implementation. As discussed in recommendation 1, this level of authority is needed because revising the charter of the FACA-governed DGAC to evolve this entity into the
proposed DGSAC will result in at least one-time and possibly continuing costs.
Evidence of Implementation
Recommendation 3a is that NEL staff plan and conduct systematic reviews with input from technical expert panels (TEPs), perform a risk-of-bias assessment of individual studies, and assist the DGSAC as needed. As noted in recommendation 1, explicitly constituted TEPs were not created as part of the 2020–2025 DGA cycle. In response to the 2017 National Academies report, USDA and HHS stated that:
NESR (formerly known as NEL) reviews were completed in a collaborative manner between the NESR team and the [Dietary Guidelines] Advisory Committee. The NESR team of scientists has expertise both in systematic review methodology and in nutrition, public health, epidemiology, psychology, library science, or a related field. The Advisory Committee members hold advanced degrees in medicine or science and included experts that are nutrition scientists, physicians, dietitians, epidemiologists, and clinicians. (DGA, 2021)
According to the two Departments, the TEP function was undertaken by “DGAC subcommittees with review and input from the full committee” (NASEM, 2022b).
For the risk-of-bias assessment for individual studies, “NESR used a dual, independent process for risk-of-bias assessments” (DGAC, 2020). Additionally,
for each article included, two NESR analysts independently completed the risk-of-bias tool appropriate for the study’s design and if a disagreement between analysts could not be resolved, an additional member of the NESR staff was asked to provide a third-party consultation. (DGAC, 2020)
Recommendation 3b is for NEL systematic reviews to be externally peer reviewed prior to being made available for use by the DGSAC. Each systematic review for the 2020–2025 DGA underwent an internal peer review, in contrast to previous DGA cycles, during which no peer review was conducted (DGAC, 2020; DGA, 2021). USDA and HHS stated that:
Each systematic review was peer reviewed by two Federal scientists. In total, 47 Federal scientists from USDA, HHS (including NIH [National Institutes of Health], CDC [Centers for Disease Control and Prevention], and FDA [Food and Drug Administration]), [the] Department of Defense, and the Department of Veterans Affairs participated in the process…. Peer reviewer comments were provided to the Advisory Committee [DGAC] and to the NESR team. NESR reviewed the comments, addressed editorial comments, and proposed edits for the Advisory Committee to review in response to substantive comments. (DGA, 2021)
Recommendation 3c is that the DGSAC synthesizes and interprets the results of systematic reviews and draws conclusions about the entire body of evidence. As noted in recommendation 1, the DGSAC was not created. As a result, the DGAC synthesized and interpreted the results of the systematic reviews and drew conclusions from them. Each step of the systematic review process is described in the 2020 DGAC Scientific Report (DGAC, 2020; USDA, n.d.b). The Departments stated:
The NESR team and the 2020 [Dietary Guidelines] Advisory Committee had distinct roles in the systematic review process. The NESR team facilitated all aspects of planning, conducting, and documenting the work necessary for timely execution of the systematic reviews in accordance with NESR methodology. The role of the 2020 Advisory Committee was to develop systematic review protocols, synthesize evidence, and develop and grade conclusions. (DGA, 2021)
In addition, the Departments stated that the DGAC, without support from NESR,
Integrated the evidence by looking across all of its conclusions—from systematic reviews, data analysis, and food pattern modeling—to develop overarching advice for USDA and HHS to consider as the Departments developed the next edition of the Dietary Guidelines. (NASEM, 2022b)
Evidence of Constraints to Implementation
The Departments stated that the reason for not establishing TEPs for the systematic reviews coordinated by NESR for the 2020–2025 DGA was not having sufficient time and resources (Stoody, 2019). This meant that it was too late for a TEP to provide assistance in advance of the DGAC’s needs. As noted in recommendation 1, additional barriers to using TEPs identified by the Departments were staff availability, limited transparency, and timeliness of work (NASEM, 2022b).
Although the Departments implemented a new peer-review process for the systematic reviews, the committee did not have information to determine why the peer-review process was restricted to internal federal scientists versus external scientists with subject-matter and methodological expertise. As discussed for recommendation 1, the 2017 National Academies report arrived too late in the DGA cycle to recharter the DGAC to the DGSAC, and USDA emphasized that because the creation of the DGA is an “unfunded mandate” for USDA and HHS (Appendix D), there was not sufficient funding to support changing the charter (see recommendation 1 for additional details).
The committee found that recommendation 3 was partially implemented, and that the Departments made progress toward fulfilling recommendation 3. Fully implementing the recommendation would have required creation of the DGSAC and use of TEPs.
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 to develop the 2020–2025 DGA, but TEP functions were undertaken by the DGAC (NASEM, 2022b). This was possible because members of the DGAC had expertise in topics relevant to the 2020–2025 DGA. For recommendation 3b, the committee found that peer review of the systematic reviews occurred for the first time (in the history of the DGA), but it did not have information to identify constraints that would explain why experts external to the Federal government were not included in the review as recommended by the 2017 National Academies report. Finally, 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.
Expected Effect of Full Implementation on the 2020–2025 DGA
Overall, the committee could not ascertain how the full implementation of recommendation 3 would have affected 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. The committee did not have information to determine how peer review that included experts external to the federal government would have changed the results of the systematic reviews. Finally, 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.
The committee views recommendation 4 as critical for developing trustworthy DGA. Recommendation 4 outlined several strategies for achieving ongoing alignment of NESR methodology with best practices (Box 4-4).
Alignment with best practices does not mean that NESR must align all practices with those of other leading systematic review groups, as NESR systematic reviews are created for a unique purpose. However, this unique purpose requires transparency around why the various best practices used by leading systematic review organizations were or were not relevant and feasible for the NESR process (Appendix D; NASEM, 2017a).
Recommendation 4 was directed to the Secretary of USDA because the Secretary’s support is required to provide resources for incorporating external systematic review experts into the strategic planning to identify best practices and to implement refinements to those practices (NASEM, 2017a). However, responsibility for addressing alignment of NESR practices with best practices currently lies with NESR staff and was accomplished during the 2020–2025 DGA process through a strong Continuous Quality Advancement (CQA) initiative. (Appendix D; DGA, 2021).
Evidence of Implementation
Alignment with Best Practices
USDA briefly describes CQA on its website (USDA, n.d.b) and explained to the committee that CQA work was accomplished through
self-directed interest groups (Appendix D). The CQA interest groups focus on
topics [that] are identified and selected by NESR based on after-action input from experts and NESR staff following the completion of each NESR review project, monitoring of evolutions occurring in the fields of systematic review and nutrition science, and from other key resources, such as the 2017 National Academies report. (DGA, 2021)
USDA reported that, when appropriate and feasible, refinements to NESR methodology are carefully planned and tested between DGAC cycles (Appendix D; NASEM, 2022b). USDA identified examples of refinements implemented during the short time period between when the 2017 report was released and the 2020 DGAC was convened (Appendix D; NASEM, 2022b; Spill et al., 2022). The Departments further stated:
Examples of process improvements that NESR made prior to supporting the 2020 Advisory Committee related to (1) tools and processes for assessing the risks of bias of primary research, (2) criteria for grading the strength of evidence underlying the conclusion drawn in NESR systematic reviews, and (3) technology to support efficient and accurate searching for and screening of studies, as well as data extraction. (DGA, 2021)
When selecting topics to pursue, USDA indicated that priority was given to “topics that enhance the rigor and transparency of NESR’s work, promote diversity of expertise and a deliberative process, while managing potential biases and conflicts of interest” (Appendix D).
Recommendation 4a is enabling ongoing training of the NEL staff. The USDA website describes the training of NESR personnel as:
Staff also receives extensive hands-on training, which occurs over a period of months and continues with ongoing professional development, to be able to independently perform each step involved in NESR methodology. (USDA, n.d.a)
In addition to formal training, between 2017 and 2020 the CQA Interest Groups (CQA-IG) completed projects related to meta-analysis, risk-of-bias, grading methodology, scoping methodology, and literature screening (Box 4-5; Appendix D). The full list of activities is in Appendix D. As shown in Box 4-5, some but not all, of the topics identified in the 2017
National Academy’s report (denoted with asterisks) were addressed prior to development of the 2020–2025 DGA.
Recommendation 4b is enabling engagement with, and learning from, external groups on the forefront of systematic review methods. CQA-IGs are a primary avenue for engaging external systematic review
organizations. USDA assembled a list of more than 50 different resources or collaborators engaged in systematic reviews (Appendix D). In addition, USDA engages in a long-standing, after-action evaluation process that includes input from the DGAC on the various aspects of the process, including NESR methodology (Schneeman et al., 2021; Snetselaar et al., 2021).
Recommendation 4c is inviting external systematic review experts to evaluate the NEL’s methods periodically. As described above, USDA indicated that the CQA program includes “periodic evaluation of NESR’s methods by systematic review experts and nutrition scientists, specifically the two NASEM Committees examining the Dietary Guidelines process” (DGA, 2021; Appendix D). As part of the CQA-IG topic activities, a wide variety of resources and experts may be invited to provide insight on these specific topics. The NESR systematic review methodology was also evaluated by external systematic review experts as part of peer review for publication of NESR systematic reviews in scientific journals.
Recommendation 4d is investing in technological infrastructure. USDA implemented several changes to its technological infrastructure during the process to develop the 2020–2025 DGA. Changes included the use of a new software program, DistillerSR, for managing search results and extracting data from systematic reviews (DGAC, 2020). In addition, USDA made considerable investment to refine the DGA website to promote transparency during the DGAC’s active period and to gather public comments on the systematic review process (Appendix D). In addition, NESR indicated that
We have not identified any improvements or technologies through our CQA program that could not be implemented. That means…we have evaluated our methodology and that of others, and adopted the refinements our team determined necessary to enhance NESR’s methodology. (Appendix D)
Evidence of Constraints to Implementation
Given that the CQA work is primarily accomplished between DGAC cycles, the timing of the release of the 2017 National Academies report (NASEM, 2017a) may have limited NESR’s ability to explore and refine
all the systematic review improvements identified in the 2017 National Academies report (NASEM, 2022b).
The committee found that, before the 2020 DGAC was convened, USDA made improvements to further align NESR with best practices identified in the 2017 National Academies report (Box 4-5; NASEM, 2022a). The committee found that the NESR CQA process has engaged several leading groups with systematic review expertise to evaluate nearly every component of the systematic review process (Appendix D). However, the committee found methodological differences between NESR practices and those of some leading systematic review organizations, particularly in the method to use and/or update existing systematic reviews, continuous evidence monitoring, and methodology for assessing evidence quality (NASEM, 2022a). The information about the CQA program did not document criteria used to determine whether refinements to NESR processes are needed and what decisions USDA made (Appendix D). It is unclear if the differences identified in the committee’s midcourse report had been previously identified, explored, and decisions made that no refinements were necessary, or that they had not yet been identified for exploration (NASEM, 2022a).
For recommendation 4a, the committee found that NESR engaged in a strong CQA program, including both initial training for NESR staff and ongoing learning through participation in CQA-IGs involving “landscape analysis” and assessment of methods and training materials for each component of the systematic review process from other leading organizations; many of these initiatives are ongoing (Appendix D).
For recommendation 4b, the committee found that NESR listed a wide variety of leading systematic review organizations that NESR had previously or were currently engaging as part of the CQA-IGs (Appendix D).
For recommendation 4c, the committee found that as part of the CQA-IG process, USDA invites experts to provide input on 25 example topics that NESR identified (Box 4-5; Appendix D). 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 to be pursued appears internally driven, with NESR staff identifying the topics from input from key stakeholders. In contrast, the National Academies 2017 report recommendation indicated that strategic planning and topic identification should be accomplished by both federal and nonfederal experts (i.e., the proposed DCGPG) (NASEM, 2017a).
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. USDA also refined the DGA website to support many of the enhancements to promote public comment and transparency during the DGAC deliberations.
Expected Effect of Full Implementation on the 2020–2025 DGA
The committee found that recommendation 4 was substantially implemented. The committee also concluded that several refinements were made between the DGAC’s work for the 2015–2020 DGA process and the DGAC’s work for the 2020–2025 DGA process to align NESR processes with best practices. Some notable differences remain, such as updating systematic reviews and adapting grading methodology. The committee did not have information to determine whether additional NESR refinements or different refinements would have changed any of the systematic review findings such that they would have affected the 2020–2025 DGA.
The committee views recommended enhancements to food pattern modeling (Box 4-6) as an important step toward capturing the complexity of dietary intake and ensuring that the food patterns developed are appropriate for the diverse U.S. population. The 2017 report committee recognized that the food pattern modeling used in the DGA process was generally appropriate and useful for informing decision-making by the DGAC and federal writing team but thought that the modeling could be strengthened (NASEM, 2017a).
The food pattern modeling that has been used in the DGA process focuses on representing the overall population using population average energy and nutrient requirements, typical food choices, and a traditional American diet. It also has not accounted for the heterogeneity of food groups consumed. Thus, the modeling addresses a limited number of
questions. Moreover, the applicability of the resulting food patterns to population groups that follow a different consumption pattern has been limited.
The committee concurs with the 2017 report committee’s recommendation to apply complex systems models to represent the mechanisms by which diet affects health and to enable consideration of a greater array of food combinations. The intended result of using such models is “making dietary recommendations as transparent, applicable, and robust as possible” (NASEM, 2017a). The 2017 National Academies report noted the need for a stepwise approach by examining how changes in modeling affect the resulting food patterns (NASEM, 2017a). Such changes might be based on other data sources, such as systematic reviews. Accordingly, while some modeling might be conducted in advance of the first meeting of the DGAC, the food pattern modeling might be iterative throughout the development of the DGAC Scientific Report and the DGA.
The 2017 National Academies report recommended that TEPs be used to supplement the expertise of individuals who make decisions about food pattern modeling groups, specifically to help verify key assumptions in the development of food patterns. The report also noted that the assumptions should be transparent, structured to use current evidence, and sufficiently flexible to adjust to reflect new research (NASEM, 2017a).
Recommendation 5 was directed to the Secretaries of USDA and HHS and has implications for staff and other stakeholders. Enhancing the food pattern modeling will require advancing capabilities, including systems modeling, as identified in the 2017 National Academies report, and such expertise could be supplemented through the use of TEPs. Other stakeholders, including members of the DGAC (or the proposed DGSAC), have a role to play in informing the analysis (e.g., identifying required sensitivity analyses) and interpreting the food pattern modeling. This addresses the potential need for systems science expertise on the DGAC (or the proposed DGSAC).
Evidence of Implementation
As noted in the committee’s midcourse report, food pattern modeling employed in the process to develop the 2020–2025 DGA used the same top-down approaches as in previous DGA cycles (NASEM, 2022a). The modeling was used to assess the ability to meet nutrient recommendations for each life stage through variations in USDA food patterns and the relationship between consumption of added sugars and intake recommendations. Additionally, the modeling informed the development of two new food patterns for infants 12 to 24 months of age (DGAC, 2020).
According to the 2020 DGAC Scientific Report, a life-stage approach was used to test how proposed changes to food pattern components affect the food group amounts and amounts of added sugars, oils, and saturated fat, as well as nutrient adequacy across the lifespan (DGAC, 2020). Nutrient profiles for food groups used in the modeling were based on a weighted average of nutrient-dense forms of foods (DGAC, 2020) tailored to each life-stage group. Modifications that were tested included the number of servings from the food groups, food group nutrient profiles, and inclusion and exclusion of certain foods or food groups (DGAC, 2020). According to information from the Departments, the food patterns offer flexibility for tailoring to cultural and taste preferences (DGAC, 2020) because, although the food group and subgroup amounts are prescriptive, the types of foods to be consumed are not. For each food pattern modeling question, the DGAC developed and made available a protocol with an analytic framework that described the scope, approach, data, and analyses to be conducted. The protocols were posted online, discussed at public meetings of the DGAC, and made publicly available on the DGA website (DGA, n.d.).
According to information from the Departments:
USDA and HHS plan to continue advancing the food pattern modeling process through a variety of activities, including engagement with external experts. These efforts will ensure that the Dietary Guidelines food pattern modeling process stays current with best practices, provides evidence-based dietary patterns for Americans, and demonstrates USDA and HHS’s commitment to process advancement. (DGA, 2021)
The two Departments further noted that they are:
accomplishing CQA in food pattern modeling and related methodologies through the work of the Food Pattern Modeling Interest Group (FPM IG). This self-directed workgroup includes staff from HHS and USDA and was tasked with determining what enhancements can be made to further advance the food pattern modeling methodology to better reflect the complex interactions involved, variability in intakes, and range of possible healthful diets. (Appendix D)
the FPM IG has also evaluated the analytic methods and development of data inputs and constraints for food pattern modeling and are in the process of completing landscape and comparative analyses to compare methods used in the development of guidance in other countries, as well as other modeling exercises described in scientific publications and the recommendations in the 2017 NASEM report. (Appendix D)
Evidence of Constraints to Implementation
To implement this recommendation fully, including the use of systems modeling, advances in modeling capabilities are needed, which suggests a continuous and long-term process. While any allocation of resources (e.g., staff time or training) would allow some adoption of systems approaches, the degree to which these approaches can be implemented is a function of the resources allocated. Thus, given the timing of the release of the 2017 National Academies report, there were constraints on what was possible to implement during the development of the 2020–2025 DGA. Nonetheless, it may have been possible to begin to explore systems science approaches by engaging expertise within and outside the federal agencies.
The committee found that some refinements were made to the food pattern modeling during the process to develop the 2020–2025 DGA to account for variability in intakes and address a range of possible healthy dietary patterns. However, the analytic methods did not change and TEPs were not employed to support the food pattern modeling. There remains a need to enhance the food pattern modeling to account for the heterogeneity of the population and its dietary patterns, specifically by incorporating systems modeling. Ongoing evolution in capabilities and application is needed as methods advance, with transparent criteria to determine when changes are made to the methods used to shape the USDA food patterns.
Expected Effect of Full Implementation on the 2020–2025 DGA
The committee had limited information to determine how the recommended food patterns and the broader 2020–2025 DGA would have changed had methods been applied that were designed to address the complexity of food intake patterns. However, the lack of full implementation of this recommendation is expected to have implications for the capacity of the food pattern models to reflect the heterogeneity of the population and variability of food patterns and thus, the rigor of the DGA.
The 2017 National Academies report called for standardizing the methods and criteria for establishing nutrients of concern both within and across DGA cycles (NASEM, 2017a). The current committee views it as important to standardize the methods used to identify nutrients of
concern, given the relevance of identified nutrients of concern to policies, programs, and future research (NASEM, 2017b; O’Neil, 2018; Cashman and Hayes, 2017). The 2017 National Academies report noted that
Standardization would lead to consistent development of quantitative thresholds of inadequacy or excess and the integration of other supportive evidence to identify a nutrient of concern. This consistency would facilitate comparisons of descriptive data analyses over time, benefiting practitioners, consumers, and the food sector. (NASEM, 2017a)
Differences noted in identifying nutrients of concern in prior DGA cycles related to not only the thresholds used but also “the degree to which biochemical and chronic disease-related data were available and used to justify the designation” (NASEM, 2017a). The report also recommended documenting the descriptive data analyses commonly used across previous DGACs.
The 2017 National Academies report suggested that TEPs could be employed to supplement the expertise of groups conducting descriptive data analyses (e.g., to refine research questions so that results would be available for the DGAC [or proposed DGSAC] when it first convenes (NASEM, 2017a). The DGAC (or proposed DGSAC) would then independently evaluate the evidence and develop conclusions in consultation with appropriate methodologists as needed (NASEM, 2017a).
Recommendation 6 (Box 4-7) was directed to the Secretaries of USDA and HHS and requires the involvement of USDA and HHS staff and members of the DGAC (or the proposed DGSAC and TEPs). Further, the descriptive data used are collected by different federal agencies, and analytic methods—such as those for estimating distributions of usual intake—have been developed by the National Cancer Institute (Tooze et al., 2006, 2010), which suggests the need for coordination across agencies.
Evidence of Implementation
As outlined in the 2020 DGAC Scientific Report (DGAC, 2020) and the subsequent peer-reviewed paper by Bailey et al. (2021), the DGAC employed a framework that standardized the terminology, thresholds, analytic methods, and interpretation related to nutrients of concern. The DGAC acknowledged that the thresholds for identifying inadequate or potentially excess intake were arbitrary. However, Bailey et al. determined the thresholds to be sufficiently low to have adequate sensitivity as screening criteria (Bailey et al., 2021). The framework used to identify nutrients of public health concern builds on the integration of biochemical and health-related data, though the 2017 report committee and the DGAC noted that biochemical data are lacking (NASEM, 2017a; DGAC, 2020).
Data analyses related to nutrients of concern were initiated early in the process. Further, a protocol that included the framework used to identify nutrients of public health concern and detailed the data and subsequent analysis to be conducted was made available before any data were reviewed and synthesized.
Evidence of Constraints to Implementation
Given that a framework related to nutrients of concern was developed and published, it is evident that the timeline and cost were not constraints to the implementation of this recommendation. However, while standardization of terminology, definitions, and thresholds for nutrients of concern for the subsequent DGA cycle was amenable to rapid implementation, other aspects of the recommendation require a serial application and the expansion of research to identify biomarkers that better reflect nutrient intake and chronic disease outcomes (NASEM, 2017a). In addition, the 2017 report committee noted that recommendation 6 pertained to actions to be taken within and between cycles, but the committee’s assessment was limited to the process of developing the 2020–2025 DGA.
As noted in the committee’s report, Evaluating the Process to Develop the Dietary Guidelines for Americans, 2020–2025: A Midcourse Report (NASEM, 2022a), the committee found that the 2020 DGAC Scientific Report (DGAC, 2020) and a later peer-reviewed publication (Bailey et al., 2021) 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. However, within the 2017 National Academies report, approaches to examining the evidence, including descriptive data analyses considered by the 2015 DGAC, were covered in Chapter 6 and approaches to assessing nutritional adequacy by the 2005, 2010, and 2015 DGACs were covered in Chapter 7 (NASEM, 2017a). Therefore, the 2017 National Academies report may have served as partial documentation of descriptive data analyses used in prior DGA cycles in the interim. Additionally, TEPs have not yet been employed to supplement the expertise of groups conducting descriptive data analyses.
Expected Effect of Full Implementation on the 2020–2025 DGA
This recommendation was almost fully implemented, therefore no further effect on the 2020–2025 DGA is expected to have occurred. 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. However, the descriptions of analyses used in prior DGA cycles within the 2017 National Academies report may have served as partial documentation in the interim.
The committee views recommendation 7 (Box 4-8) as a key, cross-cutting recommendation for the redesign of the process for establishing the Dietary Guidelines for Americans (NASEM, 2017a). In this recommendation, the 2017 report committee provided the rationale for implementing a systems approach, indicating that
It is recommended to account for and understand the interrelated factors at play in both population and individual health. The DGA can play a key role in advancing the understanding of the role of diet within the larger body of evidence on factors that affect health. (NASEM, 2017a)
The 2017 report committee described how systems methods (e.g., systems maps and models) can “lead to new insights and advance knowledge of the pathways connecting diet and health.” It also described how systems approaches can be adopted for the entire DGA process, writing that
Systems thinking, when fully integrated into the DGA process and supported with systems mapping and modeling, has the potential to influence the DGA recommendations based on comprehensive knowledge of
the relationships of interest between diet and health. Systems thinking can also inform the translation of the guidelines to maximize impact and identify relevant connections across stakeholders. (NASEM, 2017a)
The committee also noted that “previous DGACs have recognized the potential value and discussed the need to move toward the use of systems approaches” (NASEM, 2017a).
This recommendation represents a significant shift in how the entire DGA process would proceed. The 2017 report committee wrote that it “envisions the nutrition systems mapping and modeling endeavor to be an ongoing process… either built into an agency or outsourced to an organization with a proven track record in systems approaches” (NASEM, 2017a). The 2017 report committee did not anticipate that all available systems approaches and methods would be incorporated immediately and instead recognized “that the development and implementation of systems approaches will be gradual, iterative, and occur over a number of years, the foundation for the process will ideally begin with the 2020–2025 DGA cycle” (NASEM, 2017a). Given the breadth of potential applications of systems science to nutrition science and the development of the DGA, the 2017 report committee targeted its recommendation to both Secretaries of USDA and HHS:
To initiate the process, the secretaries of USDA and HHS ought to consider convening a group of experts to develop a strategy for the implementation of systems approaches and systems mapping and modeling in the DGA. This National Academies committee envisions a workshop, which includes relevant federal and nonfederal expertise, to discuss the options for integrating systems approaches into the DGA and result in strategic short and long-term plans. (NASEM, 2017a)
Given that the implementation of systems science represents a shift in the overall process of developing the DGA, support from the Secretaries
of USDA and HHS is needed. Necessary support may include convening experts to provide guidance on the implementation of systems science, securing resources to facilitate the process changes, and providing funding to develop new systems science approaches, methods, and tools.
Evidence of Implementation
The Departments stated that they:
recognize the importance of exploring how to integrate systems approaches into the Dietary Guidelines process. CNPP [Center for Nutrition Policy and Promotion] has sought funding to do so each fiscal year since 2018, but had yet to secure any funds. Contingent on funding, the Departments plan to start the important process of examining best practices for adapting the complex methodology of systems approaches and applying it to the Dietary Guidelines as effectively as possible, while ensuring that the Dietary Guidelines continues to reflect the highest scientific integrity and contain information adaptable for public health and consumer use. (DGA, 2021)
As noted in the committee’s midcourse report, neither the convening of experts nor the workshop occurred (NASEM, 2022a). However, USDA and HHS stated in 2022 that:
USDA recently secured funding to start the process of examining best practices for adapting the complex methodology of systems approaches and applying it as effectively as possible, while ensuring that the Dietary Guidelines continues to reflect the highest standard of scientific integrity and contain information adaptable for public health and consumer use. (Appendix D)
Evidence of Constraints to Implementation
The Departments stated that timing and costs may have prevented extensive implementation of the recommendation within the 2020–2025 DGA cycle. However, these two constraints likely would not have prevented some movement toward implementation. For example, the expert convening and workshop recommended by 2017 National Academies report should not have been too costly or time consuming to implement.
As noted in the committee’s midcourse report, the committee found that none of recommendation 7 was implemented as proposed.
Expected Effect of Full Implementation on the 2020–2025 DGA
Full implementation of recommendation 7 was not expected to occur within this cycle. It is difficult to determine specifically how initial, partial implementation may have affected the 2020–2025 DGA because such implementation could have occurred in many different forms and to many different degrees.
Conclusions for Recommendation 1
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 a change to their process during the cycle to develop the 2020–2025 DGA that partially met the intent of redistributing of some of the functions of the DGAC, but that there were important barriers to the creation of the DGPCG that 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 available to assess how full implementation of this foundational recommendation would have affected the 2020–2025 DGA. The committee also concluded that not having created a DGPCG during the process of developing the 2020–2025 DGA means that the subsequent DGA process has begun without the strategic planning and insights from external scientific experts that could be valuable for the 2025–2030 DGA edition.
Conclusions for Recommendation 2
The committee concluded that recommendation 2 was substantially implemented, as the 2020–2025 DGA were largely aligned with the 2020 DGAC Scientific Report. However, full implementation of this recommendation would have contributed to improved transparency and thus, the improved integrity of the DGA.
Conclusions for Recommendation 3
The committee concluded that recommendation 3 was partially implemented. While the roles of both NESR and the DGAC were defined, the sharing of some tasks between groups indicated that some elements of this recommendation were not implemented as envisioned by the 2017
report committee, which called for a clear separation of tasks between NESR and the DGSAC. 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.
Conclusions for Recommendation 4
The committee concluded that recommendation 4 was substantially implemented. The strong CQA initiative to align NESR processes with best practices led to significant refinements prior to conducting the 2020 DGAC systematic reviews. However, other potential refinements, such as updating systematic reviews and adapting grading methodology, were not addressed. The committee could not ascertain whether there would have been implications for the 2020–2025 DGA if the remaining suggested NESR refinements or different refinements had been implemented. Full implementation of this recommendation and ongoing effort to maintain best practices for conducting systematic reviews for population-level nutrition guidelines are critical for maintenance of the rigor and integrity and thus, the trustworthiness of the DGA.
Conclusions for Recommendation 5
The committee concluded that recommendation 5 was partially implemented. Some refinements were made to the food pattern modeling used to develop the 2020–2025 DGA, but the analytic methods used did not change. The committee had limited information to determine how the 2020–2025 DGA would have been affected by 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’s food patterns, with implications for the rigor of the DGA.
Conclusions for Recommendation 6
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 implementation of recommendation 6 are unlikely to have substantially impacted the 2020–2025 DGA, either with respect to their content or their perceived rigor.
Conclusions for Recommendation 7
The committee concluded that none of recommendation 7 was implemented as proposed, although full implementation of recommendation 7 was not expected to occur within this cycle. The committee concludes that 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 DGA.
The seven recommendations of the 2017 National Academies report form a plan for redesigning the process for developing the DGA in a way that is expected to increase the rigor and integrity of the DGA and result in a more transparent and trustworthy process. Some of the seven recommendations are mutually dependent, while others focus on strengthening methods. Recommendation 1 is viewed as overarching for the entire redesign.
Mutually Dependent Recommendations to Strengthen the DGA Process
Although these seven recommendations were discussed above as separate entities, the committee acknowledges that many are mutually dependent. For example, recommendation 1 endorsed creating the DGPCG, rechartering the DGAC to become the DGSAC, and using TEPs. Not creating or using these groups not only affects the success of recommendation 1 but also affects the redesign of the process as a whole and makes implementing the subsequent recommendations challenging. The committee identified three situations in which the mutual dependency of the recommendations was important. All three of these situations involve the addition of external scientific expertise to the DGA process to make the process more deliberative.
First, the creation of the DGPCG would serve several functions. It would add external scientific expertise to the process of providing oversight and planning for the next edition of the DGA and full implementation of recommendation 3. The DGPCG could also contribute to recommendations that require more than one cycle to implement. These include working with NESR staff members to identify needs for updating NESR’s methods and provide oversight of updating of systematic reviews (NASEM, 2017a). In addition, the DGPCG might contribute to the implementation of systems methods, which will require a long-term, sustained
effort (NASEM, 2017a), and the standardization of the criteria for identifying nutrients of concern across cycles.
Second, the 2017 National Academies report recommended the inclusion of experts who are external to the federal agencies in several of these recommendations (NASEM, 2017a). The purpose of including external experts was to provide the agencies with additional, informed perspectives and permit them to access technical expertise that was not available within the federal government. Moreover, it was thought that the inclusion of such expertise would improve the quality and transparency of the 2020 DGAC Scientific Report (NASEM, 2017a). However, these specific uses of external expertise were not involved in the 2020–2025 DGA cycle. The primary input from external expertise in that cycle was from the members of the DGAC.
Third, the use of TEPs was described in recommendation 1 as a way to provide content and methodological consultation by federal and nonfederal experts during the evaluation of the evidence (see Box 4-1). These expert panels would not only be advantageous for evaluation of the evidence but also serve “as a mechanism to supplement the technical insights in the beginning stages of any type of analysis” (NASEM, 2017a). The use of TEPs could also provide an efficient way to speed up the implementation of recommendations 3, 4, and 5 and allow the proposed DGSAC to focus on evidence synthesis and conclusions.
The committee concluded that no additional non-federal expertise was added to the 2020–2025 DGA process. Therefore, the 2017 report committee’s objective to achieve a more deliberative process has not yet been achieved.
Strengthening Analysis and Advancing Methods
Improving the methods used to create the DGA was a major focus of the proposed redesign of the process. This pertained to the methods used for developing the systematic reviews (recommendation 4), food pattern modeling (recommendation 5), and descriptive data analyses and identification of nutrients of concern (recommendation 6).
Incorporating systems methods into the process to develop the DGA (recommendation 7) is important, as such methods would help facilitate “comprehensive knowledge of the relationships of interest between diet and health” (NASEM, 2017a), inform connections across stakeholders, and inform translation of the DGA for maximum impact. As discussed in Chapter 2, advancing systems methods has implications for the capacity of the DGA to reflect the heterogeneity of the population. This has follow-on effects on the integrity of the DGA, as well as their perceived relevance to the diverse population. As also discussed in Chapter 2, the process to
develop the DGA involves complex data and methods. Systems methods could be advantageous for creating and implementing an analytic framework to capture the complexity of working with the many data sources and considerations. The application of systems modeling to food pattern modeling (recommendation 5) might be seen as a pathway to the use of systems methods more broadly.
With the exception of making refinements to the systematic review process and some enhancements to the food pattern modeling as well as standardizing the process of identifying the nutrients of concern, the committee concluded the proposed analytic and methodologic improvements to the DGA process had largely not yet been achieved. As noted in Chapter 2, the DGA process still lacks an overall analytic framework.
The recommendations developed by the 2017 National Academies report committee were designed to improve the rigor and integrity of the process to create the DGA and, thereby, the trustworthiness of the guidelines (NASEM, 2017a). In Task 3, the committee considered both if and to what extent the recommendations had been implemented under the known constraints of the timing of the recommendations within the process to develop the 2020–2025 DGA and the cost to implement them. The committee also considered how full implementation of these recommendations, if they had not been fully implemented, would have affected the rigor, integrity, and perceived trustworthiness of the 2020–2025 DGA.
Recommendations 2, 4, and 6 were substantially implemented. These recommendations were intended to provide the public with a clear explanation when the DGA differed from the DGAC Scientific Report (recommendation 2), ensure that the systematic reviews created for the DGA align with best practices (recommendation 4), and standardize the methods and criteria for establishing nutrients of concern (recommendation 6). The implementation of these recommendations was not constrained by timeline or cost. The committee concluded that further implementation of these recommendations would not likely have affected the content of the 2020–2025 DGA, but the gaps in implementation of recommendations 2 and 4 could have affected their integrity and perceived trustworthiness.
Recommendations 1 (to prioritize topics to be reviewed in each DGA cycle and redistribute the functions of the DGAC to three separate groups) and 7 (to develop and implement systems approaches into the DGA) were not implemented. The Departments made important changes in their processes that addressed some of the rationale for their response
to recommendation 1. No changes toward implementation of recommendation 7 were made during the 2020–2025 DGA process. The implementation of these two recommendations was constrained by timeline and cost. The 2017 report committee expected that full implementation of these recommendations would take time, so it is not surprising that they were not fully implemented within a single, ongoing DGA cycle. That committee expected that implementation of recommendation 1 would contribute to the development of a more deliberative process, as well as increased transparency, rigor, and integrity of the DGA. The 2017 report committee expected that implementation of recommendation 7 would substantially improve the transparency, rigor, and integrity of the DGA as well as the ability of the DGA to address the needs of the diverse U.S. population.
Recommendation 3 (to separate the roles of NESR [formerly NEL] and the DGSAC [still operating as the DGAC] relative to the systematic reviews) and recommendation 5 (to enhance food pattern modeling), which were designed to strengthen the analyses and advance the methods used to develop the DGA, were partially implemented. The 2017 report committee expected that these enhancements to the DGA process would reduce the risk of bias and improve the rigor of the process. The Departments made important changes in their processes that addressed some of rationale for recommendation 3. The elements of recommendations 3 and 5 that were implemented were not dependent on the implementation of recommendations 1 and 7. The committee concluded that further implementation of these recommendations could have affected the content of the 2020–2025 DGA as well as the rigor, integrity, and generalizability of these guidelines.
The committee used its scientific expertise and judgment for those recommendations that were not implemented, as data were absent or limited for predicting the form that implementation of these recommendations would have taken and, therefore, the possible effects of their full implementation on the DGA. Overall, the committee concluded that it was not possible to ascertain the possible effects of full implementation of these recommendations on the rigor, integrity, and perceived trustworthiness of the 2020–2025 DGA. The committee further 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 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.
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