Examining differences in school hour and school day dietary quality among Canadian children between 2004 and 2015.

<bold>Objective: </bold>The present study aimed to: (i) evaluate changes in Canadian children's dietary quality during school hours and on school days between 2004 and 2015; and (ii) explore whether changes in dietary quality over time were moderated by sociodemographic characteristics.<bold>Design: </bold>Nationally representative 24 h dietary recall data were obtained from the 2004 (n 4827) and 2015 (n 2447) Canadian Community Health Surveys. Dietary quality was measured using the Canadian Healthy Eating Index (C-HEI) which evaluates respondents' compliance with 2007 national dietary recommendations, and the school-HEI which assesses respondents' dietary quality during school hours. Multivariable regression models compared differences in dietary quality between 2004 and 2015. Interaction effects were used to test whether changes over time were moderated by sociodemographic characteristics (sex, age group, ethnicity, residential location, province of residence, parental education, food security status).<bold>Setting: </bold>Canada.<bold>Participants: </bold>Children aged 6-17 years.<bold>Results: </bold>Mean school-HEI score rose from 51.3 to 58.0 points (maximum = 100) from 2004 to 2015 (P < 0.001). School-HEI sub-scores for total vegetables and fruit, whole fruit, dark green and orange vegetables, milk and alternatives, and meat and alternatives improved over time, but remained well below recommendations. Decreased energy from minimally nutritious foods accounted for 39 % of the improvement in mean school-HEI scores. Mean whole day C-HEI scores also improved (60.8 to 66.4 points, P < 0.001). There was no evidence of a moderating effect for any of the sociodemographic variables examined.<bold>Conclusions: </bold>Mean dietary quality of Canadian children during school hours and on school days improved modestly for all age and sex groups but remained below 2007 national dietary recommendations. [ABSTRACT FROM AUTHOR]