Should Priorities be Improving Dietary Records or Validating Biomarkers?
The American Society for Nutrition (ASN) published a list of nutrition research priorities this year. Among the tools needed to advance nutrition research, databases are listed (along with omics, bioinformatics, biomarkers, and cost effectiveness analysis). While food databases are important to monitor food and nutrition security (nutrient availability in the region), validated biomarkers reflect dietary exposure and current nutrient status. Because of our rapidly changing food supply, it is almost impossible to accurately monitor the nutrient content of all foods and beverages in the marketplace. Biomarkers are a means to assess individual health and the nutritional status of a population.
Today’s main citation demonstrates this point. Giovannelli and colleagues assessed the validity of a qualitative food frequency questionnaire (FFQ) to evaluate individuals’ food intake compared to 3 consecutive day food records. The correlation coefficient was <0.4 for one third of the 24 questions. That is not a very strong correlation. Among the best were the correlations found between fish and EPA (r=0.43) and DHA (r=0.39).
The reality is that people are not very good at recalling or recording what they ate. Gersovitz and colleagues found that as the number of days of record increases, so does the number of incomplete records. We are also terrible at estimating portions. As proof, look at the International Association for the Study of Obesity maps. If we eat prepared foods, it is difficult to know the number of calories (or nutrient content) of the food(s) on our plate. And sometimes we don’t want to admit how much we ate. Goris and colleagues reported that obese men underreported energy intake by 37%.
In general it is difficult to get accurate estimates of portions or calories. The doubly labeled water (DLW) technique is the best biomarker of habitual energy intake. Comparing the DLW technique with other dietary assessment tools, Trabulsi and Schoeller wrote “there was not an obvious relationship between reported intake and reporting accuracy.”
Researchers continue to search for methods to address reporting bias. Perhaps it would be better to invest time and effort validating nutritional biomarkers. This could also have the advantage of clearing the path forward to make dietary intake recommendations for other bioactive compounds, including omega-3 fatty acids, lutein, zeaxanthin, and flavonoids.
Giovannelli J, Dallongeville J, Wagner A, Bongard V, Laillet B, Marecaux N, Ruidavets JB, Haas B, Ferrieres J, Arveiler D, Simon C, Dauchet L. Validation of a short, qualitative food frequency questionnaire in French adults participating in the MONA LISA-NUT study 2005-2007. 2013 J Acad Nutr Diet doi:10.1016/jand.2013.07.002
Gersovitz M, Madden JP, Smiciklaswright H. Validity of 24-hr dietary recall and 7-day record for group comparisons. 1978. J Am Diet Assoc 73:48
Goris AHC, Westerterp-Plantenga MS, Westertep KR. Undereating and underrecording of habitual food intake in obese men: selective underreporting of fat intake. 2000 AJCN 71:130
Trabulsi J, Schoeller DA. Evaluation of dietary assessment instruments against doubly labeled water, a biomarker of habitual energy intake. 2001 Am J Physiol: Endo & Metab 281:E891
Gaine PC, Balentine DA, Erdman Jr JW, Dwyer JT, Ellwood KC, Hu FB, Russell RM. Are dietary bioactives ready for recommended intakes? 2013 Adv Nutr doi:10.3945/an.113.004226