Abstract
Our aim was to assess the validity of the brief-type self-administered diet history questionnaire (BDHQ15y) to estimate the protein intake in 248 Japanese secondary school students (mean age = 14.2 years), using urinary biomarkers as references. Participants provided three samples of overnight urine for measurement of urea nitrogen and creatinine levels, underwent anthropometric measurements, and answered the questionnaires. Additionally, 58 students provided 24-h urine specimens. A significant correlation was observed between excretion of urea nitrogen in overnight and 24-h urine specimens (ρ = 0.527; p < 0.001), with biases ≤5.8%. The mean daily protein intake estimated from urinary biomarkers was 76.4 ± 20.4 g/d in males and 65.4 ± 16.9 g/d in females, and the mean protein intake estimated from the BDHQ15y (PRTbdhq) was 89.3 ± 33.7 g/d in males and 79.6 ± 24.6 g/d in females. Crude and energy-adjusted coefficients of correlation between PRTbdhq and protein intake estimated from urinary biomarkers were 0.205 (p = 0.001; 0.247 for males and 0.124 for females), and 0.204 (p = 0.001; 0.302 for males and 0.109 for females), respectively. The BDHQ15y is a low-cost tool to assess protein intake of a large population, instead of a weakness of overestimation.
Highlights
Dietary intake is closely related with health outcomes in school-age children, which includes risks of cardiovascular, digestive, bone, and allergic diseases [1,2,3,4]
The subjects (N = 28) excluded from the analysis were similar to the subjects for analysis in terms of age, body height, body weight, and physical activity (p > 0.39), except for energy intake estimated from the BDHQ (3548.8 kcal; p < 0.001) No statistically significant difference was found in any variable between individuals who were able to provide 24-h urine and those who were not able to do so (p = 0.81–0.88), except for the urinary creatinine concentration (172.3 mg/dL ± 66.3 vs. 151.1 mg/dL ± 57.9, p = 0.029), and the rate of individuals in puberty (89% vs. 76%, p = 0.012), which were higher in individuals who were able to provide overnight urine only
We could estimate the protein intake of secondary school students from biomarkers measured in overnight urine samples
Summary
Dietary intake is closely related with health outcomes in school-age children, which includes risks of cardiovascular, digestive, bone, and allergic diseases [1,2,3,4]. Dietary habits of macronutrient and food intake are known to be retained from childhood to adulthood [5,6,7], and unhealthy dietary habits are associated with cardiovascular risks in adults [8]. The school period provides adolescents with an opportunity to learn about healthy nutritional habits, which can be crucial for their health outcomes in adulthood. In order for the implementation of health education programs, a food frequency questionnaire (FFQ) is a valuable means to evaluate dietary habits among adolescents, as they are easy to administer and to answer, and they allow the nutritional assessment of a large population with a relatively low cost. They are susceptible to variables like cognitive performance, social preference, and body and health status [9].
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