The degree of misreporting of the energy-adjusted intake of protein, potassium, and sodium does not differ among under-, acceptable, and over-reporters of energy intake

It is unclear whether misreporting of nutrient intakes differs according to energy reporting status. We examined misreporting of dietary protein, potassium, and sodium in under-, acceptable, and over-reporters of energy intake. Our hypothesis was that degree of misreporting of these three nutrients differs among under-, acceptable, and over-reporters. Participants were 1043 Japanese women aged 18 to 22 years. Self-reported dietary intake was obtained using a diet history questionnaire. Under-, acceptable, and over-reporters of energy intake were identified based on the ratio of self-reported energy intake to estimated energy requirement (<0.70 [17.2%], 0.70-1.30 [78.1%], and >1.30 [4.7%], respectively). Misreporting of dietary protein, potassium, and sodium was assessed against the corresponding biomarker-based estimate derived from 24-hour urinary excretion. On average, the degree of misreporting of intake of energy and the three nutrients varied considerably. Absolute intake (amount per day) of the three nutrients was under-reported in under-reporters of energy intake and over-reported in over-reporters compared with acceptable reporters. However, mainly because of high correlations between the ratio of self-reported energy intake to estimated energy requirement and the ratio of self-reported to biomarker-based estimates of absolute intake of three nutrients (Pearson correlation coefficient: 0.64 for protein, 0.51 for potassium, and 0.37 for sodium), the degree of misreporting of the energy-adjusted intake of these nutrients based on the density method did not differ across categories of energy reporting status. In conclusion, these findings may lend support to the usefulness of adjustment for energy misreporting and the futility of merely excluding energy misreporters from analysis. (C) 2012 Elsevier Inc. All rights reserved.