Evaluations of school-based and fiscal efforts on diet-related behaviors and weight, emphasizing fruit, vegetables, candy, and soda

Bente Øvrebø of the Faculty of Health and Sport Sciences at the University of Agder has submitted her thesis entitled «Evaluations of school-based and fiscal efforts on diet-related behaviors and weight, emphasizing fruit, vegetables, candy, and soda» and will defend the thesis for the PhD-degree Wednesday 30 March 2022.

She has followed the PhD-programme at the Faculty of Health and Sport Sciences at the University of Agder.

Summary of the thesis by Bente Øvrebø:

Evaluations of school-based and fiscal efforts on diet-related behaviors and weight, emphasizing fruit, vegetables, candy, and soda

The thesis is based on three separate school-based and fiscal initiatives implemented during the 21st century in Norway.

The overall aim of the thesis was to evaluate the effects from these school-based and fiscal efforts on diet-related behaviors and weight, with a particular emphasis on fruit, vegetables, candy, and soda.

Three papers were included in the thesis.

A school-based educational program

Paper I focused on the Fruit and Vegetables Make the Marks (FVMM) project, a study initiated in 2001.

The sample comprised 38 schools (1,950 pupils) from two Norwegian counties.

Eighteen schools were randomized to the intervention, and 20 served as controls.

The intervention comprised a multicomponent school-based educational program administered for one school year in an effort to increase fruit and vegetable intake.

Furthermore, nine of the intervention schools in one county were given free fruit at school, resulting in a subgroup receiving the multicomponent educational program and free school fruit and vegetables.

Data were collected in 2001 (baseline: mean age of 11.8 years) and in four additional follow-up collections before the final one in 2016, when the pupils were adults (mean age: 26.5).

The analyses found no differences in fruit or vegetable intake among adults who in childhood had received the multicomponent educational program compared with the controls.

Among the subgroup of individuals who received free school fruit and vegetables, no synergistic effect from the multicomponent educational program on adult fruit and vegetable intake was found.  

Nationwide free fruit and vegetable policy

Paper II: An evaluation of the nationwide free fruit and vegetable policy providing pupils with a daily piece of fresh fruit or vegetables (Paper II), implemented from 2007 to 2014, was possible due to the policy’s rollout, in which some schools were exposed, while others were not.

By utilizing cross-sectional and longitudinal anthropometric data from four national representative cohorts from the Norwegian Childhood and Youth Growth studies, a quasi-natural experimental design was used to evaluate the effects from policy exposure on weight outcomes at ages 8.5 and 13.

Heterogeneity was examined in effects across exposure duration, sex, and socioeconomic status.

Pooled models indicated no consistent beneficial or unintended effects from 1–2.5 years of exposure to the policy on weight outcomes at age 8.5 or at age 13, with up to four years of exposure. 

Tax rise on candy and soda

Paper III: In Norway, the previously existing taxes on candy and soda were raised abruptly, effective January 1, 2018.

The abrupt increases in candy and soda taxes – 80% and 40%, respectively – were evaluated using a quasi-experimental design (Paper III).

By accessing retail sales data from nearly all Norwegian grocery stores, sales of candy and soda during the season with the tax increases were compared with sales during the season before the tax hikes (control season).

Two models were used to evaluate the effects from the tax increases on volume sales of candy and soda, with one estimating the immediate effect on sales and another estimating average changes in sales.

The analyses revealed no detectable reductions in sales of the taxed products that coincided with the tax increases.  

No effects

The school-based and fiscal efforts evaluated in this thesis did not yield detectable or consistent effects on diet-related behaviors and weight, emphasizing fruit, vegetables, candy, and soda.

De skolebaserte og fiskale tiltakene som ble evaluert i avhandlingen ga ingen påviselige eller konsistente effekter på ernæringsrelatert atferd eller vektstatus, med fokus på frukt, grønnsaker, søtsaker og brus.