Nutrient adequacy of Japanese schoolchildren on days with and without a school lunch by household income

BACKGROUND: Evidence for whether the nutrient intakes of Japanese schoolchildren differ according to household income is sparse. OBJECTIVE: We investigated the role of school lunches for nutrient adequacy among Japanese primary school children using dietary reference intakes in a cross-sectional survey. DESIGN: Participants were 10- to 11-year-old (5th grade) children from 19 public primary schools in four prefectures of East Japan, and 836 children were analyzed. The participants completed 24-h dietary records with photographs of their meals for 4 consecutive days, composed of 2 days with and 2 days without a school lunch. −Children’s household income was obtained from questionnaires that were completed by the participants’ guardians and divided into the following three categories: low (0.2236–2.2361 million yen; n = 319), middle (2.3333–2.8868 million yen; n = 194), and high (3.1305–6.3640 million yen; n = 323). Logistic regression analyses were used to estimate the odds ratios for whether participants had poor nutrient intakes, with adjustment for confounders. RESULTS: On days without a school lunch, the prevalence of nutrient shortages was significantly higher compared with those on days with a school lunch for most macro- and micronutrients among all three levels of household income. Children from low-income households had higher rates of nutrient shortages for vitamin B(6), pantothenic acid, K, Mg, P, Fe, and Zn than those from middle-income households on days without a school lunch (P = 0.004, 0.001, 0.001, 0.006, 0.037, <0.001, and 0.015, respectively), but those differences were not significant on days with a school lunch. CONCLUSION: The findings suggest that school lunches are important for achieving adequate nutrient intakes in schoolchildren and reduce disparities of adequate nutrient intake by household income levels.