Evaluation of free school fruit on childhood growth and obesity: a natural experiment

Obesity in childhood is an increasing problem. One purpose of the project was to obtain a nationally representative description of height and weight among 13-year-olds in Norway. A random sample of school classes was therefore selected, and public health nurses took measurements during school hours. Using the national identity number, information from some registries was linked, both to understand the development of growth through information from the Medical Birth Registry and child health clinic and school health measurements, and information on socioeconomic variables from Statistics Norway. The project is funded by a grant from the Research Council of Norway. We estimated the prevalence of overweight, obesity, and thinness among Norwegian 13-year-olds and the changes from childhood (age 8 years) to adolescence (age 13 years). Among 13-year-old Norwegians, the prevalence of overweight (including obesity), obesity, and thinness was 15.8%, 2.5%, and 7.3%, respectively. There was little evidence that these had changed from 8 to 13 years. From 8 to 13 years, the odds of obesity was highest in the Northern region of Norway compared to the South-Eastern region and higher in rural compared to urban areas. Over the same age period, there was a higher proportion of girls than boys in the thinness category. We also examined to which extent free fruit in schools may influence weight development in school-children. In Norway, free fruit was given to pupils in some schools, but not in others, in the period 2007 to 2014. By measuring height and weight in 13-year-old children in a representative sample in 2017, we use this natural experiment to evaluate effects of free fruit in schools. Our evaluation indicated no consistent beneficial or unintended effects from 1–2.5 years of exposure to the free fruit policy on weight outcomes at age 8 or at age 13, with up to four years of exposure for some children.

Prosjektet har bidratt med kunnskap om forekomst av overvekt og fedme blant barn i Norge og vist at den gjennomførte gratis skolefruktordningen ikke hadde effekt på forekomsten av overvekt. Denne kunnskapen er nyttig når politikk som skal fremme helse og sunne spisevaner skal utformes og rettes mot målgrupper. The project has contributed with new information about the prevalence of overweight and obesity among children in Norway and shown that the implemented free school fruit policy did not have effect on the occurrence of overweight. This knowledge is useful when policies promoting health and healthy eating habits are to be formulated and targeted.

Childhood and adult obesity is a substantial public health concern. Political actions that aim to reduce the prevalence of obesity and overweight in modern societies are needed. We are in a unique position to be able to estimate the effect of a natural experiment. In Norway, in the period 2007-2014, free fruit was offered to school children in some schools, but not in others. By using data on height, weight (body mass index, BMI) and waist circumference in 8-year and 13-year old children in addition to growth data from birth linked through registries, available in the Norwegian Child Growth Study (NCG), we can estimate the effect of a free fruit program in schools. This study therefore directly responds to the call for proposals about understanding the effects of interventions. The primary objective of the project is to evaluate the effect of free school fruit on childhood growth and obesity, by exploiting this natural experiment. We will also describe socio-economic patterns of growth and obesity and investigate whether this free school fruit intervention may contribute to reducing social inequalities. Our project will be supported by a methodological work package that will improve our understanding of the growth of Norwegian children, and through the application of several causal inference approaches, improve our understanding of the potential causal effect of the school fruit intervention. The latter will be key to evaluating the extent to which such an intervention is likely to improve health. This is critical information for translating research findings into effective policy. This research may ultimately contribute to improving the health of younger generations, and may have particular relevance to tackling social and ethnic health inequalities.