5

Concluding Remarks

In this chapter, the Committee on Evaluating the Process to Develop the Dietary Guidelines for Americans, 2020–2025 (USDA and HHS, 2020) provides overall conclusions from its work to date and some reflections about it.

ADDRESSING THE FIVE VALUES

To achieve the goal of trustworthiness, the National Academies of Sciences, Engineering, and Medicine (the National Academies) report Redesigning the Process for Establishing the Dietary Guidelines for Americans (2017 National Academies report) (NASEM, 2017) identified five values to improve the integrity of the process to develop credible and trustworthy guidelines. These were to

• Enhance transparency,
• Promote diversity of expertise and experience,
• Support a deliberative process,
• Manage biases and conflicts of interest, and
• Adopt state-of-the-art processes and methods.

The committee endorses these five values as providing an essential starting point for identifying ongoing systematic improvements that can be made to the process to develop the Dietary Guidelines for Americans (DGA). It is noted that some of the organizational challenges that led to

criticisms in the past and to the articulation of these five values by the 2017 committee still exist. Indeed, it is the current committee’s consensus that future versions of the DGA will remain vulnerable to the kinds of critiques that they have received previously until these five values are firmly embedded in the DGA process.

OVERARCHING CONCLUSIONS

In this midcourse report, the committee first focused on addressing task 1 (see Chapter 3) to provide the U.S. Department of Agriculture (USDA) and the U.S. Department of Health and Human Services (HHS) with timely feedback on their progress toward redesigning and improving the processes used to establish the DGA in response to the seven 2017 National Academies recommendations. Based on the committee’s analysis, findings, and conclusions provided in Chapters 3 and 4, several overarching conclusions have been reached.

First, the committee concluded that there has been significant progress toward the implementation of these recommendations as a group, as discussed in detail, recommendation by recommendation, in Chapter 3. Nonetheless, progress toward full implementation has been uneven. The 2017 National Academies recommendations with the longest lead time and/or the greatest bureaucratic hurdles were the ones least likely to have been implemented. There are several understandable reasons for this. The recommendations in the 2017 National Academies report were, to varying degrees, aspirational and provided long-term directions that could strengthen the entire DGA process (NASEM, 2017).

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. The committee believes that these recommendations are essential for enhancing the integrity of the DGA. As a result, those recommendations or components thereof that were not fully implemented remain important, and work toward them should be continued or initiated. These recommendations include the reorganization of committees and their functions to achieve a transparent, deliberative, and unbiased process (recommendation 1) and the introduction of systems science and innovative technologies across essentially all of the DGA processes (recommendation 7) to provide the infrastructure necessary to advance the scientific development of the DGA (NASEM, 2017).

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. In particular, these include fuller development of transparency, which is necessary to demonstrate a lack

of bias, ensure accountability, and enhance perceived integrity (NASEM, 2017). All of these contribute to public acceptance of the DGA, which is essential for their adoption and use by the U.S. population.

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 (see Chapter 2, Figure 2-2). Timing created the most problems for the creation of the two new recommended committees, the Dietary Guidelines Planning and Continuity Group (DGPCG) and the Dietary Guidelines Scientific Advisory Committee (DGSAC), as the creation of two new committees has to be approved through the Federal Advisory Committee Act (see Appendix B). Unfortunately, this has meant that both the strategic planning for the DGA cycle that was to be carried out by the DGPCG and the realignment of functions that was to be created between the Nutrition Evidence Library (now Nutrition Evidence Systematic Review [NESR]) and the DGSAC has not yet occurred.

Fifth, two other 2017 National Academies recommendations that were difficult to implement had challenges with lead time, namely the recommendations to strengthen food pattern modeling and to introduce systems-science approaches to the DGA process. Both of these recommendations will require investments in specially qualified personnel and new scientific approaches. Thus, both will require additional financial support, which USDA and HHS indicate they have requested for several years but have not yet received (see Appendix B). These investments remain essential if USDA is to retain its position as a leader in food pattern modeling and to be able to bring appropriate technology to bear on one of the most difficult challenges of the DGA process, namely the diversity of the U.S. population in terms of characteristics related to dietary patterns and health status.

Sixth, systematic reviews were a major focus of the committee’s effort for this midcourse report as they appeared in both recommendation 4 (see Chapter 3) and task 2 (see Chapter 4). To address this task and recommendation, the committee created a set of identified practices and used this set to help determine the extent to which the specific aspects of systematic reviews named in these tasks had been implemented (see Appendix E). Relative to recommendation 4, the committee concluded, as a result of what NESR was already doing and the enhancements made in response to the 2017 National Academies report, the systematic review processes were generally aligned with committee-identified practices. Relative to task 2, which was focused on the subset of systematic reviews with chronic disease outcomes, 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. Further enhancements

in the methods to use and update existing systematic reviews represent an important opportunity for development, as does the implementation of ongoing surveillance of published research. Perhaps the most challenging of these is developing an evidence base that is generalizable or applicable with regard to the health status of study participants to public health guidance (task 2 question, see Chapter 1, Box 1-2). The evidence base is currently limited by the exclusion of research on secondary prevention and the strategy for choosing studies from other countries for inclusion in systematic reviews. This is potentially problematic because the U.S. population is diverse in many characteristics related to both diet and health. It is noteworthy that this challenge is not limited to creating the DGA, as the U.S. government faces this challenge for many of its policies and programs.

Finally, the committee identified many instances of partial implementation of the recommendations from the 2017 National Academies report. Some of these (e.g., recommendation 6) were minor concerns. Many other concerns that might, individually, seem minor represent a more substantial concern when considered together. For example, the many seemingly small deviations from committee-identified practices for systematic reviews together reduce the quality and utility of this important element of the evidence used to develop the DGA. Moreover, the combined effect of recommendations for which there were substantial concerns with those that were not implemented at all represents a continuing risk to the integrity of the DGA process.

FINAL REMARKS

The committee concentrated on the specific recommendations contained in the 2017 National Academies report about the process for creating the DGA and has begun its examination of the role of systematic reviews in the development of recommendations for diet-related chronic disease. The 2017 National Academies report’s proposed improvements to the processes for establishing the DGA were designed to create a process that is more effective and trustworthy. The current committee’s analysis indicates that USDA and HHS have implemented many of the recommendations related to trustworthiness. In addition, the improvements proposed in the 2017 National Academies report would enhance the ability of DGA to address more complex problems, such as those required to make dietary recommendations for a population diverse in health status and other personal characteristics. There is room for improvement here as the proposed investments in food-pattern modeling and in systems science have not been implemented. These investments are essential for providing the DGA process with the capacity to make recommendations

that address the high proportion of individuals in the U.S. population who are at risk of or are living with diet-related chronic disease, as well as to address the diversity of eating patterns that characterize the U.S. population. The committee’s analyses to date indicate that the evidence base used for the systematic reviews conducted for the Scientific Report of the 2020 Dietary Guidelines Advisory Committee (DGAC, 2020) was current and remains “thorough” as noted in the 2017 National Academies report. Nonetheless, there is room for improvement in the systematic-review process. This would involve attending to some of the fine details noted by this committee as well as creating a framework within which the systematic reviews are developed, as described in the 2017 National Academies report (NASEM, 2017). It would also involve improving the generalizability of the systematic reviews. Expanding the generalizability of these systematic reviews to all Americans is a difficult undertaking but one envisioned as the result of the implementation of recommendations made in the 2017 National Acadmies report.

The committee noted explicitly what is often implicit: the DGA are highly public facing, as they provide advice on good nutrition that is used by consumers and professionals throughout the health sector to make personal health decisions. In addition, the DGA are also government facing because they are integral, indeed required, underpinnings to other federal nutrition programs, which must design their programs to meet the DGA. Therefore, 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.

REFERENCES

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