Drawing attention to: US Dietary Guidelines: Science is "Subpar," Cannot be Replicated
Article by science journalist Nina Teicholz
Summary be ChatGPT 4.0
A new paper published in the American Journal of Clinical Nutrition (AJCN) exposes significant methodological shortcomings in the systematic reviews (SRs) underpinning the U.S. Dietary Guidelines for Americans (DGA), calling into question their scientific reliability. These guidelines, issued by the USDA and HHS, have shaped national nutrition policy since 1980. However, according to the study led by Alexandra M. Bodnaruc and David Moher, the SRs are "suboptimal" and of "critically low quality."
Key findings include:
Irreproducible Search Results: Attempts to replicate the USDA's literature search revealed major errors, yielding 10,201 papers compared to 3,550 in the USDA's results—a threefold discrepancy caused by flawed search strategies.
Lack of Quantitative Analysis: The USDA opted for narrative reviews rather than rigorous meta-analyses, which are considered more reliable.
Non-Transparent Practices: The USDA did not pre-register protocols with independent bodies, use open materials, or complete standard checklists for systematic reviews.
Potential for Bias: The absence of methodological rigor exposes the process to biases, potentially undermining the guidelines' credibility.
Despite these issues, most nutrition experts continue to support the guidelines' fundamental recommendations—emphasizing fruits, vegetables, whole grains, nuts, seafood, and low-fat dairy—while ignoring systemic criticisms. Critics, such as Chirag Patel of Harvard, highlight the influence of biases in the USDA's process, warning that it limits the generalizability and trustworthiness of findings.
The USDA has faced similar critiques before, including a 2017 National Academies of Sciences, Engineering, and Medicine (NASEM) report that recommended substantial reforms to the review process, none of which were fully implemented. Critics like Nina Teicholz argue that the guidelines remain "untrustworthy," yet nutritionists broadly dismiss challenges to their validity, prioritizing continuity over addressing methodological flaws.
This ongoing controversy raises concerns about the scientific integrity of a policy meant to guide public health, particularly as diet-related diseases continue to rise.