Nutrient adequacy of Japanese schoolchildren on days without a school lunch as an alternative to household income

Background and objectives: School lunches are important for adequate nutrient intakes in children. Nutrient intake is inadequate among children from low-income households on days without a school lunch. However, questions about household income are often not responded to due to privacy reasons. We conducted a cross-sectional study to develop a questionnaire to assess nutrient adequacy of children on days without a school lunch as an alternative to household income. Methods: Participants were 691 children aged 10-11 years from 19 public primary schools in four prefectures of East Japan. The participants completed 24-h dietary records with meal photographs for 2 days without a school lunch. Children's guardians completed a questionnaire about reducing their intakes of the following foods due to economic reasons: "fruits and vegetables", "meat and fish", "food you wanted", and "food you needed". Using reference dietary intakes, intakes of energy and 25 nutrients were evaluated to assess nutrition adequacy. Logistic regression analyses were used to estimate the odds ratio for poor nutrient intake in participants, after adjustment for confounders. Results: Participants who often or occasionally reduced their intakes of fruits and vegetables due to economic reasons had significantly higher rates of inadequate intakes of energy and 7 nutrients (vitamins A, E, and B2, K, Ca, Mg, and P) compared to those who did not or rarely reduced their intakes. Participants who often or occasionally reduced their intakes of the foods they wanted due to economic reasons had significantly higher rates of inadequate intakes of energy and 7 nutrients (proteins, fibers, vitamins E, B2, and C, Ca, and P) compared to those who did not or rarely reduced their intakes. Only a few nutrients showed significant differences between the respondents to questions about reducing their intakes of meat and fish, and foods they needed. Importantly, those nutrients also showed significant differences among respondents to the first two questions. Conclusions: The questions about reducing children's intakes of fruits and vegetables, and food they wanted due to economic reasons are useful to assess nutrient adequacy on days without a school lunch as an alternative to household income.