WASHINGTON, Sept. 14, 2017 - The process used to develop the Dietary Guidelines for Americans every five years needs an overhaul to increase efficiency and transparency, and enhance credibility, says a new report from the National Academy of Sciences.
Specifically, the NAS committee that issued the report recommended establishing three separate groups to replace the current Dietary Guidelines Advisory Committee, which produces the advisory report used by USDA and the Department of Health and Human Services to develop the DGA.
In the DGAC’s place would be a new Dietary Guidelines Planning and Continuity Group that would prioritize topics to include in the DGA and conduct strategic planning, the Dietary Guidelines Scientific Advisory Committee (DGSAC), which would interpret scientific evidence and draw conclusions, and technical expert panels to provide support during evaluation of the evidence.
“The Dietary Guidelines for Americans have the promise to empower Americans to make informed decisions about what and how much they eat to improve health and reduce the risk of chronic disease,” said Robert Russell, professor emeritus of nutrition and medicine at Tufts University and NAS committee chair.
“Despite this potential, fewer than 10 percent of Americans consume a diet fully consistent with the DGA.”
Russell said that “a more trustworthy, agile, and effective process can improve the relevance and usefulness of the DGA, which may ultimately improve adherence to the guidelines. The new process advanced by the committee would “allow for the appropriate expertise and time to focus on each step of the process, which can be achieved by reallocating the steps to a balanced and expanded set of multidisciplinary experts,” he said.
The Center for Science in the Public Interest said the report “makes two critical points. First, while the process of evaluating scientific evidence could be strengthened, the Dietary Guidelines for Americans are based on solid scientific methods. Second, improvements to make the process more transparent will bolster trust in the government’s advice to consumers."
"Of course, what the country really needs are policies that help Americans eat according to the sensible, science-based advice in the guidelines," CSPI said. "Contrary to much reporting of pendulums swinging back and forth, the advice in the guidelines has been rather consistent over the years."
The report said that one way to make the process more efficient is to use the entire five years.
“Within a five-year cycle, the current process allots two years for evaluation of the science and for making conclusions by the DGAC, and one year for developing the DGA Policy Report by the government,” the report said. “The remaining two years of the five-year cycle is a period of relative inactivity.” The committee “believes that using the entire five years for work on the DGA will 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 general public.”
NAS contends the way the DGA works now puts too much pressure on the DGAC, which exists for about two years in the middle of the five-year DGA process. “The DGAC conducts all tasks associated with scientific review, limiting opportunities for a truly deliberative process with the nutrition community, technical experts, and the public,” NAS said in a news release on the report.
Another problem with the current system is the lack of a clearly stated purpose. The committee said it found more than 10 different statements of purpose for the 2015-2020 guidelines, released in early 2016.
The committee proposed the following language: “The purpose of the DGA is to provide science-based ‘nutritional and dietary information and guidelines for the general public’ that form the basis for ‘any federal food, nutrition, or health program’ (based on the National Nutrition Monitoring and Related Research Act).”
In addition to redesigning the process, the committee recommended that the secretaries of USDA and HHS clearly explain to the public when the guidelines “omit or accept only parts of conclusions from the scientific report.”
Other recommendations include:
- The USDA secretary “should clearly separate the roles of USDA Nutrition Evidence Library (NEL) staff and the DGSAC. The NEL staff would plan and conduct systematic reviews with input from technical expert panels, perform risk-of-bias assessment of individual studies, and assist the DGSAC as needed. In addition, the NEL systematic reviews should be externally peer reviewed before being made available for use by the DGSAC, which would synthesize and interpret the results of systematic reviews and draw conclusions about the entire body of evidence.”
- The USDA secretary “should ensure all NEL systematic reviews align with best practices” through training of NEL staff, engagement with external groups “on the forefront of systematic review methods,” and “inviting external systematic review experts to periodically evaluate the NEL’s methods.”
- The USDA and HHS secretaries “should enhance food pattern modeling to better reflect the complex interactions involved, variability in intakes, and range of possible healthful diets.”
- They also “should standardize the methods and criteria for establishing nutrients of concern” and “commission research and evaluate strategies to develop and implement systems approaches into the DGA. The selected strategies should then begin to be used to integrate systems mapping and modeling into the DGA process.”
“Food pattern modeling has traditionally focused on representing the overall population through use of population average energy and nutrient requirements, typical food choices, and a traditional American diet set of food groups,” the report said. “However, the heterogeneity of the population is largely not accounted for, such as the distribution of requirements for energy and all nutrients, widely varying food choices by numerous demographic factors, and some food groups not being consumed by all Americans.”
The committee recommended more use of Systems Science Approaches. “Systems approaches and methods aim at elucidating the interactions and pathways (e.g., biological, behavioral, social, and environmental) involved in complex relationships, such as the relationship between diet and health,” the report notes.
“Systems approaches (now in their infancy in the nutrition field) will help us to more clearly define the roles and limitations of diet in reducing chronic disease risk,” the report said. On a webinar Thursday morning to discuss the report, committee member Bruce Lee, a professor at Johns Hopkins who is the executive director of the Global Obesity Prevention Center, said a systems approach recognizes that “the pathway between nutrients and health and health outcomes is not a direct one,” in part because of all the factors that affect health – environmental, socioeconomic, and behavioral factors, for example.
Also on the webinar, Russell said a systems approach “brings some reality into the whole thing of what can be expected from diet.”
The report was sponsored by USDA, which will review it with HHS before deciding which of the recommendations to adopt. The latest DGA process has been underway since the last one was issued.
One thing the departments could do now, the committee members said, is to adopt the values laid out in the report:
- Enhance transparency
- Promote diversity of expertise and experience
- Support a deliberative process, in order to be adaptive and flexible
- Manage biases and conflicts of interest
- Adopt state-of-the-art processes and methods.
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