Comparison of Ultra-Processed Food Intake Estimates Between Food Frequency Questionnaire and 24-Hour Dietary Recalls: Findings from the National Health and Nutrition Examination Survey (NHANES) 2003-2006.
TL;DR
Differences in UPF intake estimates were consistently observed between FFQ and 24HDR in the overall U.S. population and across demographic subgroups, highlighting the need for standardized approaches to classifying foods according to processing level.
Abstract
Background
Ultra-processed foods (UPFs) are a major component of modern diets and are associated with many adverse health outcomes. Accurate assessment of UPF consumption is essential for nutritional research.
Objective
We compared estimates of UPF consumption derived from 24-hour dietary recall (24HDR) and food frequency questionnaire (FFQ) data in National Health and Nutrition Examination Survey (NHANES) 2003-2006 and assessed agreement between these methods in classifying UPF consumption.
Methods
This study included 10,937 participants in the NHANES 2003-2004 and 2005-2006 cycles with FFQ and 24HDR data. UPFs were classified according to the Nova classification system. Spearman's rank correlation coefficients and weighted kappa statistics were used to assess agreement between 24HDR and FFQ in estimating UPF intake. The Wilcoxon signed-rank test was used to compare mean UPF intake percentages reported by the two methods. FFQ weights were used to account for sampling.
Results
UPFs accounted for 34.7% of energy using the FFQ and 52.2% of energy intake using the 24HDR, with a mean difference of 18.9% of energy (p < 0.001). This difference was observed across age, sex, and race subgroups. There was a weak positive correlation (Spearman's r: 0.20, p<0.001) and slight agreement (weighted kappa: 0.05) in classifying energy intake from UPF using the two methods. The difference in estimating UPF intake by 24HDR and FFQ was substantially smaller after reclassifying food items on FFQ with ambiguous classification level.
Conclusions
Differences in UPF intake estimates were consistently observed between FFQ and 24HDR in the overall U.S. population and across demographic subgroups. Nova classification decisions for foods with ambiguous processing levels may contribute to differences between methods, highlighting the need for standardized approaches to classifying foods according to processing level. These findings highlight the need to further the development of dietary assessment instruments designed to capture UPF consumption.