Did You Forget About Nutrient Status?
Memory is unreliable, especially when it comes to what we eat. A report published this week challenges the data generated in the National Health and Nutrition Examination Survey (NHANES) for caloric intake, asserting that the data are so flawed they’re essentially useless. Why would the public be so interested in something as nuanced as the technical limitations of nutrient assessments?
The answer is because these data are used by lawmakers to inform nutrition policy, case in point: the US Dietary Guidelines. This report, authored by Dr. Edward Archer of the University of Alabama at Birmingham, is focused on the discrepancy between reported caloric intake (which is small) and the ever increasing obesity epidemic (which is big). He argues that memory based dietary assessments, like the 24 hour recall used in NHANES, are inherently flawed because memory is unreliable (among other reasons). Dr. Archer goes on to state that this “may explain why nutrition recommendations are continually changing and the average consumer is confused as to what constitutes a healthy diet.”
This isn’t the first time that this debate has happened. In fact, the start of 2015 marked another set of similar articles vilifying and defending memory based dietary assessments and their role in nutrition research, which were also covered in Talking Nutrition. Clearly, there are parallels when it comes to micronutrient research – that dietary intake surveys can be problematic (but I wouldn’t say that they are without value), and that objective measures such as biochemical assessments should be better utilized. We see similar discrepancies in micronutrient research: for example, the most common nutrient deficiency as measured by blood status is vitamin B6 according to the CDC, yet from a dietary intake perspective is not listed as a shortfall nutrient by the Dietary Guidelines Advisory Committee.
I believe that in the coming years we will continue to see an increasing trend of utilizing more objective methods of nutrient assessment, both for caloric intake as well as micronutrients. There is a growing interest in expanding these technologies on devices like smartphones (so called “m-Health” application), and once this technology becomes more accessible to researchers and the general public I believe this debate will end. In the meantime, while we need to remain cognizant of the limitations of traditional intake assessments, we need to continue to work towards developing more objective assessment methods.
Archer E, Pavela G, Lavie CJ. The inadmissibility of What We Eat In America and NHANES dietary data in nutrition and obesity research and the formulation of the scientific foundation of the national Dietary Guidelines. Mayo Clinic Proceedings 2015; epub ahead of print.