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Approaches to Examine the Science

Updating the Dietary Guidelines for Americans (Dietary Guidelines) is a scientifically rigorous, multi-year process. The U.S. Departments of Health and Human Services (HHS) and Agriculture (USDA) identify proposed scientific questions with input from Federal experts and the public and then appoint a Dietary Guidelines Advisory Committee (Committee). The Committee members refine and prioritize their questions, collaborate to develop protocols that describe how they plan to review the science, review and synthesize the evidence based on their protocols, present their scientific findings, and consider public comments. The Committee’s work culminates in a comprehensive scientific report on the current state of nutrition science and provides independent recommendations to HHS and USDA. Upon delivery of its report to the Secretaries or when its 2-year charter expires, whichever comes first, the activities of the Committee will finish, and the Departments will develop the next edition of the Dietary Guidelines, informed by the work of the Committee, existing evidence-based federal guidance, federal agency input, and public comments. 

The Committee uses three approaches to examine the evidence:  Data analysis, food pattern modeling, and systematic reviews. Each of these approaches has its own rigorous, protocol-driven methodology, and plays a unique, complementary role in examining the science. For each approach, staff from HHS and USDA support the Committee's review of the evidence.

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Data analysis: A collection of analyses that uses national data sets to describe the current health and dietary intakes of Americans. These data help make the Dietary Guidelines practical, relevant, and achievable.

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Food pattern modeling:  A methodology used to illustrate how changes to the amounts or types of foods and beverages in a dietary pattern might affect meeting nutrient needs and to develop quantitative dietary patterns that reflect health-promoting patterns identified in systematic reviews and meet energy and nutrient needs. 

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Systematic reviews: Gold-standard evidence synthesis projects that answer nutrition questions of public health importance using systematic, transparent, rigorous, and protocol-driven methods to search for, evaluate, synthesize, and grade the strength of the eligible body of evidence.

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Learn more about how the 2025 Dietary Guidelines Advisory Committee will use these approaches to inform the next edition of the Dietary Guidelines.