There are not many studies evaluating the long-term effects of fruit and vegetable interventions.
We examined the effects of 1 y of free fruit in elementary school on long-term consumption of fruit, vegetables, and unhealthy snacks, according to sex and educational attainment, 14 y after the intervention period.
In 2001, the baseline survey of the longitudinal cohort, Fruits and Vegetables Make the Marks (FVMM), included 1950 children (mean age: 11.8 y) attending 38 randomly drawn elementary schools from 2 counties in Norway. In the following 10 mo, 9 schools served as intervention schools by participating in the Norwegian School Fruit Program for free, whereas 29 schools served as control schools. A follow-up survey conducted in 2016 included 982 participants (50%) from the original study sample (mean age: 26.5 y). The consumption of fruit and vegetables was measured by a 24-h recall (portions per day), and the consumption of unhealthy snacks was measured by food-frequency questions (portions per week). Linear mixed models were performed to test possible intervention effects on the consumption of fruit, vegetables, and unhealthy snacks 14 y after the intervention period.
No overall intervention effects after 14 y due to the free-fruit scheme on the consumption of fruit, vegetables, and unhealthy snacks were observed, but significant interactions showed a sustained higher frequency of fruit consumption among females in the intervention group compared with the control group [mean difference (MD): 0.38 portions/d; P = 0.023] and that this effect was only significant among less-educated females (MD: 0.73 portions/d; P = 0.043). No significant long-term intervention effects were observed in the consumption of fruit among highly educated females and males nor in the consumption of vegetables or unhealthy snacks.
Results from the present study indicate that receiving free fruit at school for 1 y may have positive long-term effects for females without higher education.
CommentIn: Am J Clin Nutr. 2019 Jan 1;109(1):5-6 PMID 30624574
Little is known about the mediating effects of the determinants of fruit and vegetable (FV) intake in school-based interventions that promote FV intake, and few studies have examined the impact of the degree of implementation on the effects of an intervention. The present study examined whether the degree of implementation of an intervention had an effect on children's fruit or vegetable intake and determined possible mediators of this effect. The study is part of the European PRO GREENS intervention study which aimed to develop effective strategies to promote consumption of fruit and vegetables in schoolchildren across Europe. Data from 727 Finnish children aged 11 years were used. The baseline study was conducted in spring 2009 and the follow-up study 12 months later. The intervention was conducted during the school year 2009-2010. The effects were examined using multilevel mediation analyses. A high degree of implementation of the intervention had an effect on children's fruit intake. Knowledge of recommendations for FV intake and liking mediated the association between a high degree of implementation of the intervention and an increase in the frequency of fruit intake. Knowledge of recommendations for FV intake and bringing fruits to school as a snack mediated the association between a low degree of implementation of the intervention and an increase in the frequency of fruit intake. Overall, the model accounted for 34 % of the variance in the change in fruit intake frequency. Knowledge of recommendations acted as a mediator between the degree of implementation of the intervention and the change in vegetable intake frequency. In conclusion, the degree of implementation had an effect on fruit intake, and thus in future intervention studies the actual degree of implementation of interventions should be assessed when considering the effects of interventions.
The rationale for promoting increased consumption of fruit and vegetables (FV) at an early age is based on results from previous tracking-studies, indicating that dietary habits learned in childhood sustain into adulthood. Previous tracking studies have several limitations (e.g. low study sample, few repeated measurements and/or short a follow-up period). In addition, to our knowledge, no study has shown that a dietary intervention initiated in childhood affects tracking of dietary behaviour. The main objectives in this study were therefore to assess tracking of FV and unhealthy snacks in a large sample with multiple follow-up surveys over 15-years, and whether exposure to free school fruit for one school year modified tracking.
The longitudinal cohort-study, Fruit and Vegetables Make the Marks, included 38 randomly drawn schools in Norway; nine intervention schools received free fruit (or vegetable) in the school year 2001/2002 and 29 schools severed as control. The baseline sample included 1950 subjects, and 16-92% participated at five follow-up surveys (2002-2016). FV consumption and unhealthy snacks were measured by FFQ. Mixed models were applied to estimate overall tracking coefficients, and to assess whether the intervention modified tracking ((from baseline, from follow-up one (while intervention was running) and from follow-up two (after end of intervention)).
Overall tracking coefficients were 0.33 for fruit, 0.36 for vegetables and differed by sex for unhealthy snacks: 0.46 males and 0.39 for females (interaction p?=?0.065). Most analyses showed no significant difference in tracking between the intervention group and control group. However, from follow-up one, tracking coefficients were different for unhealthy snacks, 0.46 vs. 0.38 (interaction p?=?0.036), and from follow-up two for vegetables, 0.35 vs 0.48 (p?=?0.036), in the intervention group and control group, respectively.
Our results indicate low to moderate tracking of FV and unhealthy snacks from childhood to adulthood. We found little evidence that the free fruit intervention modified tracking of fruit, vegetables or unhealthy snacks. More research is needed on if or how we can influence the tracking of fruit, vegetables and unhealthy snacks consumption to improve public health.