Controversy and debate: Memory-Based Methods Paper 1: the fatal flaws of food frequency questionnaires and other memory-based dietary assessment methods.

There is an escalating debate over the value and validity of self-reported dietary intake as estimated by Food Frequency Questionnaires and other forms of memory-based dietary assessment methods. Proponents argue that despite limitations, memory-based methods provide valid and valuable information about consumed foods and beverages and therefore can be used to assess diet-disease relations. In fact, over the past 60 years, thousands of memory-based dietary research reports were used to inform public policy and establish the Dietary Guidelines for Americans. Yet, despite this impressive history, our position is that memory-based dietary assessment methods are invalid and inadmissible for scientific research and therefore cannot be used in evidence-based policy making. Herein, we present the empirical evidence and theoretic and philosophic perspectives that render data derived from memory-based methods both fatally flawed and pseudoscientific. First, the use of memory-based methods is founded upon two inter-related logical fallacies: a category error and reification. Second, human memory and recall are not valid instruments for scientific data collection. Third, in standard epidemiologic contexts, the measurement errors associated with self-reported data are nonfalsifiable because there is no way to ascertain if the reported foods and beverages match the respondent's actual consumption. Fourth, the assignment of nutrient and energy values to self-reported intake (i.e., the pseudoquantification of anecdotal data) is impermissible and violates the foundational tenets of measurement theory. Fifth, the proxy estimates created via pseudoquantification are often physiologically implausible and have little relation to actual nutrient and energy consumption. Finally, investigators engendered a fictional discourse on the health effects of dietary sugar, salt, fat and cholesterol when they failed to cite contrary evidence or address decades of research demonstrating the fatal measurement, analytic, and inferential flaws of memory-based dietary assessment methods.