Background Nutrient standards were introduced by the Government to all English primary schools in 2008. By restricting some products and increasing the quantity and quality of others, the standards resulted in a healthier school meal profile. Despite attention to improve the quality of school meals, packed lunches have changed little in recent years and are not covered by similar regulations. There are few published studies that compare weight, body mass index (BMI), energy and nutrient intake over the whole day according to lunch type.

Methods A dietary assessment tool named CADET was used to assess the diet of 2355 children aged 6 to 8 years attending primary schools across England. Regression analysis which took into account the clustering of children within schools was used to report anthropometric, dietary and nutritional characteristics over one 24 hour period. Nutrient and anthropometric results from children having a packed lunch were compared with children having a school meal. Results were also compared to the reference nutrient intakes (RNIs) and the National Diet and Nutrition Survey (NDNS) in children.

Results No significant differences in weight, standardised BMI, or daily energy consumption were seen between children in the packed lunch group compared to the school meal group. However, there were nutritional differences, reported here as mean difference and 95% confidence interval (95% CI). The packed lunch group consumed higher daily amounts of carbohydrates (8.1 g, 95% CI 2.2 to 14.0g, P< 0.01), sugar (9.8g, 95% CI 5.4 to 14.3, P< 0.01) and sodium (92.1mg, 95% CI 22 to 162mg, P< 0.01). Conversely, the school meal group consumed higher intakes of protein (3.3g, 95% CI 1.6 to 5g, P< 0.01), fibre (0.8g, 95% CI 0.3 to 1.3g, P<0.01) and zinc (0.2mg, 95% CI 0.05 to 0.5mg, P<0.01). Neither group met the recommended amounts for zinc, fibre or starch and indicated lower levels of sodium and higher levels of fat than the NDNS. Differences found in nutrient intake were independent of measures of child deprivation and ethnicity.

Conclusion Children taking a packed lunch to school have a less nutritious diet on average over the whole day in terms of sugar, sodium and fibre. A good quality lunch is therefore an important factor for overall dietary quality in children. Policies to encourage parents and children to include nutritious foods such as fruit, vegetables and low fat starchy foods are needed to narrow the gap between school meals and packed lunches.