"What did you eat yesterday and should we believe you?" The answer to that question, and others like it, are part of a continuing controversy about U.S. government-issued dietary recommendations presented in The Dietary Guidelines for Americans 2015-2020, which was released on January 7. Two Letters to the Editor of Mayo Clinic Proceedings follow up on a recent study and the accompanying editorial about data from the National Health and Nutrition Examination Survey (NHANES), a widely-cited source within the nutrition community.
These letters continue the debate about the validity of memory-based dietary assessment methods (M-BMs) in formulating dietary policies and recommendations for the general public. In the original article, an obesity theorist and cardiovascular health researchers claimed that the main source of dietary information used by the U.S. government's 2015 Dietary Guidelines Advisory Committee (DGAC) is scientifically inadmissible because it is based on M-BMs and people do not accurately report what they eat. In an editorial response to that article, health researchers suggested that the purported flaws are well-appreciated by nutritional researchers and can be mitigated by using multiple data sources, resulting in valid data.
While not specifically addressing the use of M-BMs, the U.S. House Committee on Agriculture met on October 7, 2015, to discuss the 2015 Dietary Guidelines for Americans. Both Tom Vilsack, Secretary of the Department of Agriculture (USDA), and Sylvia Burwell, Secretary of the Department of Health and Human Services (DHHS), testified about the DGAC, the Guidelines, and the more than 29,000 public comments that were submitted. A significant number of questions from the committee concerned the credibility of recommendations that have changed over time.
Lead author Edward Archer, PhD, of the Office of Energetics, Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham, AL, and co-authors Gregory Pavela, PhD, and Carl J. Lavie, MD, from the Department of Cardiovascular Diseases, John Ochsner Heart and Vascular Institute, Ochsner Clinical School - the University of Queensland School of Medicine, New Orleans, LA, have now commented on their original article and the editorial response. They continue to maintain that M-BMs are scientifically invalid and further that defenders of their use have ignored repeated empirical refutation and have not presented valid counter-arguments.
Archer, Pavela, and Lavie reiterate that M-BMs are "are pseudoscientific and inadmissible in scientific research and the formulation of national dietary guidelines." They continue, "it is time for the U.S. Department of Agriculture, Centers for Disease Control and Prevention, and the National Institutes of Health to recognize and acknowledge the empirical refutation of M-BMs and reexamine the extensive utilization and funding of these data collection protocols."
In a response from the authors of the original editorial, Brenda M. Davy, PhD, RD, and Paul A. Estabrooks, PhD, both from the Department of Human Nutrition, Foods, and Exercise, Virginia Tech, Blacksburg, VA, review what they consider misrepresentations and inaccuracies in the Archer et al letter. They cite references to other studies that have discussed M-BMs and their recognized limitations. "DGAC does in fact highlight the need for randomized controlled trials in many subject areas to strengthen the evidence base, as well as the need for dietary biomarker research, to better inform future dietary guidelines," explain Davy and Estabrooks.
Davy and Estabrooks also suggest another factor that may be fueling some of the controversy. Specifically, they note that there have been significant efforts by the food industry to fight proposed dietary guidelines. According to William L. Lanier, MD, Editor-in-Chief of the Proceedings, "The collective comments of these authors reflect widely held concerns among experts as well as lay people regarding the scientific foundations of governmental dietary guidelines, the interpretation of the available data, and the magnitude and direction of recent guideline changes. There may be a multiplicity of interpretations, filtered through the expertise, experiences, and goals of the interpreter. As such, it appears that thoughtful disagreements - as seen in the exchanges between Archer et al and Davy and Estabrooks - will continue, especially in light of the scientific, economic, and political perspectives of the multiple constituencies involved."