The Rigorous Process Behind U.S. Dietary Guidelines
The development of the Dietary Guidelines for Americans (DGA) is a multi-stage process led by the U.S. Department of Agriculture (USDA) and the U.S. Department of Health and Human Services (HHS). A cornerstone of this process is the evidence review, a systematic and transparent method for evaluating the body of nutritional science.
Stage 1: Identifying Topics and Scientific Questions
The DGA process begins with identifying high-priority topics and scientific questions determined by USDA and HHS, considering public comments, federal agency input, and emerging research. This differs from older methods where the Advisory Committee set its own agenda. The 2020-2025 cycle notably included guidelines for infants, toddlers, and pregnant women.
Stage 2: Appointing the Dietary Guidelines Advisory Committee (DGAC)
A Dietary Guidelines Advisory Committee (DGAC) of nonfederal nutrition and public health experts is appointed. Members are selected for their expertise and to manage conflicts of interest. This committee reviews evidence and reports findings to USDA and HHS. The formal committee structure was established following past controversies.
Stage 3: The Evidence Review and Data Analysis
The DGAC uses the Nutrition Evidence Systematic Review (NESR), a USDA team specializing in systematic reviews, along with data analysis and food pattern modeling.
The DGAC reviews evidence using three approaches:
- NESR Systematic Reviews: NESR conducts rigorous, protocol-driven reviews, which are externally peer-reviewed.
- Data Analysis: The DGAC analyzes data from national surveys like NHANES to understand U.S. dietary habits and health status.
- Food Pattern Modeling: This technique assesses how different dietary patterns meet nutrient needs within specific calorie levels.
Evidence Sources for the Review Process
The review process relies on robust national data. Key sources include:
- What We Eat In America, NHANES (WWEIA, NHANES): Provides detailed dietary intake data.
- USDA Food and Nutrient Database for Dietary Studies (FNDDS): Converts reported foods into nutrient profiles.
- USDA Food Patterns Equivalents Database (FPED): Translates foods into USDA food patterns components.
- Medical and Public Health Surveys: Offers broader context on health trends.
Modern vs. Older DGA Review Methods
The review methods have become more structured and transparent.
| Feature | Older Method (pre-2005) | Modern Method (since 2010) |
|---|---|---|
| Basis | Collective knowledge, informal reviews. | Systematic reviews (NESR), data analyses, modeling. |
| Structure | Less formal, DGAC set questions. | Structured, USDA/HHS identify topics upfront. |
| Transparency | Limited public input. | Increased public comment, peer review. |
| Scope | Ages 2 and older. | Entire lifespan. |
Stage 4: Developing and Implementing the Final Guidelines
The DGAC's report informs the final Dietary Guidelines for Americans document, but the Secretaries of USDA and HHS make the final policy decisions, also considering public and federal agency comments. The guidelines are used by various stakeholders and are available at DietaryGuidelines.gov.
Conclusion
The evidence review for Dietary Guidelines is a critical, evolving process ensuring U.S. public health recommendations are scientifically sound and current. Through systematic reviews, data analysis, and expert input, complex science is translated into actionable advice. This process adapts to new research and informs federal nutrition policies.
