Systematic review and meta-analysis of school-based interventions to improve daily fruit and vegetable intake in children aged 5 to 12 y 1 3

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1 Systematic review and meta-analysis of school-based interventions to improve daily fruit and vegetable intake in children aged 5 to 12 y 1 3 Charlotte EL Evans, Meaghan S Christian, Christine L Cleghorn, Darren C Greenwood, and Janet E Cade ABSTRACT Background: To our knowledge, no reviews have assessed the impact of a range of multi- and single-component school-based programs on daily fruit and vegetable intake by using a meta-analysis. Objective: The aim of this study was to quantify the impact of school-based interventions on fruit and vegetable intake in children aged 5 12 y. Design: A systematic literature review was carried out to identify randomized and nonrandomized controlled trials that were based in primary schools and designed to increase portions of daily fruit and vegetable intake. MEDLINE, Cochrane libraries, EMBASE, Psyc- INFO, and Educational Information Centre were searched from 1985 to 29. Data were extracted, and mean effect sizes were calculated by using random effects models. Results: A total of 27 school-based programs involving 26,361 children were identified that met the inclusion criteria and assessed the daily weight of fruit and vegetable intake combined, fruit intake only, or vegetable intake only, and 21 studies were used in metaanalyses. The results of the meta-analyses indicated an improvement of.25 portions (95% CI:.6,.43 portions) of fruit and vegetable daily intake if fruit juice was excluded and an improvement of.32 portions (95% CI:.14,.5 portions) if fruit juice was included. Improvement was mainly due to increases in fruit consumption but not in vegetable consumption. The results of the meta-analyses for fruit (excluding juice) and vegetables separately indicated an improvement of.24 portions (95% CI:.5,.43 portions) and.7 portions (95% CI: 2.3,.16 portions), respectively. Conclusions: School-based interventions moderately improve fruit intake but have minimal impact on vegetable intake. Additional studies are needed to address the barriers for success in changing dietary behavior, particularly in relation to vegetables. Am J Clin Nutr 212;96: INTRODUCTION The long-term health benefits of a diet high in fruit and vegetables in adulthood are well documented. A high intake of fruit and vegetables is associated with reduced risks of all-cause mortality (1), many cancers (2 4), cardiovascular disease (5, 6), and determinants of cardiovascular disease (7 11), which are major causes of death in developed countries (12). A low fruit and vegetable intake may also be a risk factor for obesity (13), although this effect has been disputed (14, 15). A high fruit and vegetable intake is associated with a better quality diet that is lower in energy-dense foods and higher in fiber (16 18). Findings from the global Burden of Disease 2 study suggested that 4.4% of the overall burden of disease in Europe is attributable to low intakes of fruit and vegetables (19). Childhood intake of fruit and vegetables may be related to intake in later life (2) that results in close links between poor intake in childhood and adulthood. Surveys of fruit and vegetable intake of children have reported low intakes of fruit and vegetables in most American, European, and Australian children of between 2 and 3 portions/d (16, 21 28), which are well below the 5 portions (4 g) recommended by many government departments of health (29, 3). A range of potentially modifiable characteristics are reported to be associated with a higher intake of fruit and vegetables in children. These characteristics include good availability and accessibility (31 38), taste preference and lack of neophobia (34, 37, 39), better home support (4), knowledge of national recommendations (31, 41, 42), interest in a healthy diet (42 44), and verbal praise (38, 45). These factors provide a wealth of information to shape the design of school- and communitybased interventions to increase fruit and vegetable intake in children and have been incorporated into intervention programs (46). Single-component programs provide free or subsidized fruit to children to increase availability, whereas multicomponent programs provide a range of components such as nutrition education in the curriculum, improvement of the school environment to enable healthy choices, and communication with parents to increase family support. A number of reviews of school programs to improve fruit and vegetable consumption have been conducted (47 51), 2 studies of which have included a meta-analysis that enabled the impact of programs to be quantified. Of the 2 reviews that included a meta-analysis, one review included a small number of studies (51), and one review pooled studies in which fruit and vegetable intake was assessed either over the school day or over the whole day, which resulted in a high level of heterogeneity between studies (47). This latter review may have overestimated the 1 From the Nutritional Epidemiology Group, School of Food Science and Nutrition (MSC, CLC, JEC, and CELE), and the Biostatistics Unit, Centre for Epidemiology and Biostatistics (DCG), University of Leeds, Leeds, United Kingdom. 2 No specific funding was obtained for this review. 3 Address correspondence to CEL Evans, Nutritional Epidemiology Group, School of Food Science and Nutrition, University of Leeds, LS2 9LN, United Kingdom. c.e.l.evans@leeds.ac.uk. Received November 8, 211. Accepted for publication July 1, 212. First published online September 5, 212; doi: /ajcn Am J Clin Nutr 212;96: Printed in USA. Ó 212 American Society for Nutrition 889

2 89 EVANS ET AL impact of programs because it did not take into account the fact that children may potentially increase their consumption of fruit and vegetables while at school and compensate with reductions in home consumption (52). To our knowledge, this high-quality review is the first to provide a meta-analysis of a wide range of multi- and single-component studies that measured the impact of school-based programs on daily fruit and vegetable consumption. Advanced analysis techniques were used, and the impact of programs was reported in terms of numbers of portions of fruit and vegetables. Important sources of heterogeneity were taken into account, for the first time to our knowledge, by presenting the results from studies that measured fruit and vegetables but not fruit juice. This method is important because reviews of the health benefits of fruit and vegetables generally exclude juice, which may have different associations with health outcomes. For the first time to our knowledge, results of the impact on fruit and vegetables separately are reported in meta-analyses. Improvements in daily fruit and vegetable consumption have the potential to achieve significant public health benefits, and this review identifies school-based trials that targeted fruit and vegetable intake in children aged 5 12 y to assess the impact of these programs. METHODS Search strategy An unpublished protocol was designed and agreed upon by all authors at the start of the review. The following bibliographic databases were searched: the Cochrane Central Register of Controlled Trials ( cctrdb.htm), OVID MEDLINE ( ) ( com/site/catalog/database/91.jsp), The Global Health Library ( ) ( PsycINFO ( ) ( Education Resources Information Centre ( ) ( and EMBASE ( The search-strategy method for MEDLINE included research terms in the following areas: child, fruit, vegetable, specific fruit and vegetables, public health, health behavior, health promotion, health education, intervention studies, and diet. This method was adapted so that it could be used for the other databases by using keywords when Medical Subject Headings terms were not available. Reference lists were searched for additional citations. Inclusion and exclusion criteria Dietary intervention studies in a school setting that involved children aged between 5 and 12 y (at the start of the intervention) were included. Trials (with or without random assignment) with a control or usual practice group were included. Studies were included if they used standard-assessment measures such as food diaries by using weighed or nonweighed methods, a 24-h diet recall, or food-frequency questionnaires. Studies were excluded if the intervention focused on eating disorders, such as anorexia nervosa or bulimia, or if data on children of this age group could not be extracted separately from data for other age groups. Trials that involved,1 participants were also excluded, as were trials that included only obese children. Studies were excluded if they did not include a measure of variation such as an SD or SE. Studies were excluded if they did not report the total daily fruit and vegetable consumption (eg, if they reported consumption at school only). Studies that had only.2 y follow-up were excluded as the bias was likely to be considerable with the loss to follow-up. Definitions of exposure and outcome The main outcome was the difference in portions (total weight in g/8 g) of fruit and vegetables, separately and combined, consumed daily, excluding potatoes, between intervention and control groups. This amount was the agreed portion size for fruit and vegetables, and no government has set a smaller standard portion size for children. The benefits of fruit-juice consumption are not as clear as the benefits of fruit and vegetable intake. Therefore, trials that included fruit juice together with fruit and vegetables were analyzed separately. Alternative wording from portion such as serving or serve were checked to ensure that the alternative was equal to 8 g. If the portion or serving was different from 8 g, the amount was recalculated. The US serving of one-half cup of vegetables or a medium-size piece of fruit were taken to be equal to a portion of 8 g. Selection of the studies Two independent reviewers were involved in the study identification and data extraction. In the first round of initial screening, the title and abstract of each article were checked for eligibility by one of the 2 reviewers. Articles were excluded from the title and abstract if they clearly did not meet inclusion and exclusion criteria as judged by the reviewer. In the second round of screening, full copies of potentially eligible articles were obtained, and each article was assessed by both reviewers for eligibility. Any disagreement between the 2 reviewers on whether the article was eligible was resolved by discussion between the reviewers and, when necessary, in consultation with a third reviewer. Data extraction Data were extracted by 2 independent members of the team (but not in duplicate). All data extracted were checked by a third member of the team who was trained and experienced in data extraction. Data were extracted on data-collection methods, length of program, dropouts, and analysis methods. All studies were summarized according to the following aspects: type of intervention, selection of population, outcomes, baseline and follow-up measures, and statistical analysis. Data on sample size, sample age, date and location of the study, type of control group, and unit of random assignment were also extracted. Wherever results for more than one follow-up period were reported, the longest follow-up period was used in the metaanalysis. The different types of activities included in the intervention program were identified for each study. These types of activities included the following prespecified elements: school lessons as part of the school curriculum, communications (either with parents through newsletters or with students and teachers at

3 REVIEW OF SCHOOL-BASED INTERVENTIONS 891 school), food provision such as the availability of fruit and vegetables at lunchtime or in tuck shops, free fruit and/or vegetable distribution, food marketing such as incentives to buy more fruit and vegetables at lunchtime including point-of-purchase incentives, food preparation and/or tasting during school, homebased projects including homework carried out with the help of parents, general improvements in the school environment (used if specific school-based elements were not described), and community and industry involvement such as the involvement of supermarkets or industry partners. The final element reported by mainly US studies was goal setting and problem solving, which indicated that an overarching theory-based study of planned behavior was used. Quality assessment of studies The assessment of the quality of the trials was based on the following 3 criteria: reporting of sequence generation criteria, allocation concealment, and blinding of participants, personnel, or outcome assessors. Trials were considered to be at high risk of bias if none of the criteria were met, at medium risk of bias if 1 or 2 of the criteria were met, or at low risk of bias if all 3 of the criteria were met. Statistical analysis The statistical analysis was carried out with Stata version 11 software (StataCorp). Random-effects models were used for all meta-analyses to determine pooled estimates of differences in portions of fruit and vegetables consumed in intervention compared with control groups. If results were reported as the change from baseline to follow-up in each group, the difference between groups was calculated by using the t test. Heterogeneity was assessed by using the I 2 statistic, which describes the proportion of total variation attributable to between-study heterogeneity (53). I 2 values,3% were considered to be low, values between 3% and 5% were considered to be low to moderate, values between 5% and 75% were considered to be moderate to high, and values.75% were considered to be high. I 2 values.5% indicated that caution should be used when drawing conclusions from the data (54). Forest plots were examined to review heterogeneity between studies. Possible sources of heterogeneity were explored and included the trial design (randomized or not randomized), geographic location, intervention type, diet-assessment methodology, children s age, and length of follow-up. Funnel plots were used to visually check for asymmetry and to determine the possibility of publication bias (53). RESULTS Literature search The literature search outlined in the Methods identified 2722 potential articles, including 316 duplicates (312 duplicates were identified at the first stage and 4 duplicates were identified at the screening stage), as follows: 592 articles from EMBASE, 1 articles from PsycINFO, and the remainder of articles from MEDLINE. A total of 67 articles that potentially met all criteria as a result of screening titles and abstracts were identified. A total of 2656 articles were excluded (before deduplication) on the basis of the predetermined exclusion factors. Many articles were excluded on medical grounds such as eating disorders (12 studies), a nut allergy (396 studies), or other medical conditions that concerned negative aspects of plants on health (711 studies). A number of articles were excluded in which the outcome was not the daily weight of fruit and vegetables (439 studies) or were not controlled trials (172 studies). Some studies were excluded because of the age of the children (25 studies). Scrutiny of the remaining 67 articles identified 4 additional articles for exclusion, which resulted in 27 remaining studies. Reasons for exclusion at this second stage are shown in Figure 1, with the wrong age group and outcome other than the daily weight of fruit and vegetables as primary reasons for exclusion. A summary of the studies included in the qualitative review on daily intake are shown in Table 1. The sample size of each study represents the number of children included in the analysis with baseline and follow-up data available. The total number of participants included in all studies was 26,361, with a mean of 99 children/study (median: 486 children/study). Programs delivered a variety of interventions that were delivered over a range of 3 FIGURE 1. Flow diagram indicating number of studies included at each phase of the review.

4 892 EVANS ET AL TABLE 1 Characteristics of studies included in the review of school-based interventions to increase daily fruit and vegetable intake 1 Study name (first author, year published, country) (reference) Sample size Sample age Intervention time: elements included in the intervention Follow-up period from start of intervention Fruit and vegetable intake in portions at follow-up Difference in fruit and Control Intervention vegetable portions Difference in fruit portions Difference in vegetable portions Nutrition Education Intervention (Anderson, 25, United Kingdom) (55) Gimme 5 (Baranowski, 2, United States) (56) Squire s Quest (Baranowski, 23, United States) (57) School Fruit Program (Bere, 25, Norway) (58) Free School Fruit (Bere, 26, Norway) (59) Fruit & Veg Make the Marks (Bere, 26, Norway) (6) Action Schools! (Day, 28, Canada) (61) Fruit & veg subscription (Eriksen, 23, Denmark) (62) 5 a Day Power Play! School only (Foerster, 1998, United States) (63) 5 a Day Power Play! School & community (Foerster, 1998, United States) (63) The National Schools Fruit Scheme (Fogarty, 27, United Kingdom) (64) School Nutrition Policy initiative (Foster, 28, United States) (65) Eat Well & Keep Moving (Gortmaker, 1999, United States) (66) Planet Health (Gortmaker, 1999, United States) (67) American Indian Nutrition (Govula, 27, United States) (68) Cardiovascular Exercise and Nutrition Program (Hopper, 1996, United States) (69) y mo mo: curriculum, communications, food provision and marketing, and food preparation and tasting mo: curriculum, communications, (1 y) 2.3 (1 y).2 3 food marketing, goal setting and problem solving, and home-based projects (2 y) 2.3 (2 y) wk: 1-session psychoeducational, multimedia game mo: free school fruit and vegetable 9 1. (median) 2. (median) 1. distribution mo: free school fruit and vegetable distribution mo: curriculum, communications, food preparation, goal setting, and home-based projects mo: curriculum, food tasting, school environment, and goal setting mo: fruit and vegetable subscription mo: curriculum and school environment mo: curriculum, school environment, and community mo: fruit-distribution scheme mo: education, policy, social marketing, and parent outreach mo: curriculum, school environment, and home-based projects boys mo: curriculum and home-based girls projects mo: curriculum mo: curriculum and home-based projects (Continued)

5 REVIEW OF SCHOOL-BASED INTERVENTIONS 893 TABLE 1 (Continued) Study name (first author, year published, country) (reference) Sample size Sample age Intervention time: elements included in the intervention Follow-up period from start of intervention Fruit and vegetable intake in portions at follow-up Difference in fruit and Control Intervention vegetable portions Difference in fruit portions Difference in vegetable portions Food Dudes (Lowe, 24, United Kingdom) (7) Internet tailored advice (Mangunkusumo, 26, Netherlands) (71) School Fruit Tuck Shops (Moore, 28, United Kingdom) (72) 5 a day Power Plus (Perry, 1998, United States) (73) School Fruit & Vegetable Scheme: remaining on scheme at 7 mo (Ransley, 27, United Kingdom) (52) School Fruit & Vegetable Scheme: leaving scheme by 7 mo (Ransley, 27, United Kingdom) (52) Fruit & veg distribution program (Reinaerts, 28, Netherlands) (74) Multicomponent program (Reinaerts, 28, Netherlands) (74) High 5 (Reynolds, 2, United States) (75) APPLES (Sahota, 21, United Kingdom) (76) WAY program (Spiegel, 26, United States) (77) Schoolgruiten project (Tak, 27, Netherlands) (78) APPLE (Taylor, 27, New Zealand) (79) mo: social marketing by using videos as part of curriculum mo: internet-based feedback from questionnaire mo: school environment (tuck shops selling fruit) mo: curriculum, school environment, food provision and marketing, home-based projects, and industry involvement mo: free school fruit and vegetable distribution 6 6 mo: free school fruit and vegetable distribution mo: free school fruit and vegetable distribution mo: curriculum, food provision, communications, home-based projects, and community mo: curriculum, food tasting, problem solving, food service, and home-based projects mo: curriculum, school environment, and food service mo: curriculum, problem solving, and home-based projects (1 y) 2.21 (2 y) (1 y) 3.2 (2 y) (white) mo: free school fruit and vegetable distribution 236 (ethnic) mo: curriculum, free fruit and vegetables, and home-based projects 1 Difference in fruit and vegetable portions between groups was adjusted for baseline whenever possible. Banded rows were not included in the meta-analysis. 2 Mean. 3, not applicable.

6 894 EVANS ET AL mo for mainly curriculum-based programs to 2 academic years for many of the more complex programs. The majority of interventions consisted of more than one component and, therefore, were categorized as multicomponent programs. These interventions often comprised a home and school element and tended to have a longer follow-up time period than singlecomponent programs. Single-component programs were mainly free or subsidized fruit-distribution schemes. In most cases, control groups were reported to receive either an intervention at a later date or usual care. Some studies did not report information on the control group, and 2 studies by Bere et al (59, 6) reported that the control group received a paid subscription for fruit compared with the intervention group that received free fruit (59, 6). The unit of randomization was normally the school, but in 2 trials, the unit of randomization was the class (69, 71), and in one study, the unit of randomization was the region (79). The median difference in daily fruit and vegetable intake between control and intervention groups for all studies included in the qualitative review was.6 portions on the basis of 27 studies, with intervention groups having higher intakes on average. Six studies were excluded at the meta-analysis stage because of a lack of measures of variation (ie, SD, SE, or CI) (62 64, 69 7, 77) One study reported the total sample size but did not provide the sample size for each group. In this case, the sample size was estimated by assuming equal numbers of children in each group, and the study was included (75). One author replied to the request for additional information on sample size for the control and intervention groups and was also included (56). All articles included reported fruit and vegetable intake over the whole day, but some studies also included fruit juice in the reported difference between groups (56, 57, 68, 75). The inclusion of fruit juice was a strong determinant of heterogeneity, and therefore, the primary analysis (Figure 2) included studies in which only fruit and vegetables, and not fruit juice, were measured. Because this was not decided a priori to be a sensitivity analysis, the inclusion of all studies was carried out in addition to the primary analysis (Figure 3). Three studies in the metaanalysis reported total consumption of fruit and vegetables and also fruit juice (56, 68, 75), whereas 9 studies reported weights of fruit and vegetables excluding fruit juice. In addition, meta-analyses are presented with differences in daily fruit intake only (Figure 4) and daily vegetable intake only (Figure 5). In the primary meta-analysis to determine differences in fruit and vegetable consumption, with the exclusion of fruit juice, the pooled estimate for interventions reported a daily difference of.25 portions (95% CI:.6,.43 portions) with higher amounts of fruit and vegetables in the intervention group (Figure 2). The difference between groups was significantly different from zero (P,.1). The I 2 value was 49% (95% CI: %, 74%; P =.4), which indicated moderate levels of heterogeneity. A funnel plot indicated that there was some suggestion of slight asymmetry (plot supplied as supplementary data; see Figure S1A under Supplemental data in the online issue), but the Egger s test for asymmetry was not statistically significant (P =.58). In the sensitivity analysis to determine differences in fruit and vegetable consumption, including fruit juice, the pooled estimate for interventions reported a daily difference of.32 portions (95% FIGURE 2. Pooled estimate of the differences in daily portions of fruit and vegetables consumed between intervention and control groups by using the longest follow-up data available and excluding studies that combined fruit and fruit juice. Weight was assigned with STATA version 11 software (StataCorp) by using n and SEM. Horizontal lines denote 95% CIs. The diamond represents the overall estimated effect. The meta-analysis used the weighted mean difference in the random-effects model. FVMM, Fruits and Vegetables Make the Marks; ID, identification.

7 REVIEW OF SCHOOL-BASED INTERVENTIONS 895 FIGURE 3. Pooled estimate of the differences in daily portions of fruit and vegetables consumed between intervention and control groups by using the longest follow-up data available and including studies that combined fruit and fruit juice. Weight was assigned with STATA version 11 software (StataCorp) by using n and SEM. Horizontal lines denote 95% CIs. The diamond represents the overall estimated effect. The meta-analysis used the weighted mean difference in the random-effects model. FVMM, Fruits and Vegetables Make the Marks; ID, identification. CI:.14,.5 portions) with amounts of fruit and vegetables higher in the intervention group (Figure 3). This difference was significantly different from zero (P,.1). Heterogeneity measured by using I 2 was moderate to high at 62% (95% CI: 31%, 79%; P,.1). A funnel plot indicated that there was some suggestion of slight asymmetry (see Figure S1B under Supplemental data in the online issue for the plot), but the Egger s test for asymmetry was not significant (P =.21). With the exclusion of fruit juice, the meta-analysis of difference in fruit only (Figure 4) reported that fruit was.24 portions (95% CI:.5,.43 portions) higher in the intervention group. This difference was significantly different from zero (P =.1). However, heterogeneity was high with an I 2 value of 78% (95% CI: 6%, 87%; P,.1). A funnel plot indicated that there was asymmetry (see Figure S1C under Supplemental data in the online issue for the plot), and the Egger s test for asymmetry was significant (P =.2). An analysis on all studies including those with fruit juice produced similar results. The difference between groups was.28 portions (95% CI:.12,.44 portions) for all studies, which was significantly different from zero (P,.1). Heterogeneity as denoted by I 2 was high at 78% (95% CI: 63%, 86%; P,.1) (forest plot not shown). Differences in vegetable intake between control and intervention groups were much smaller (Figure 5). A meta-analysis of vegetables only that included studies with fruit juice indicated an effect size of.7 portions (95% CI: 2.3,.16 portions), which was not significantly different from zero (P =.16). Heterogeneity was moderate to high with an I 2 value of 72% (95% CI: 54%, 83%; P,.1). A funnel plot indicated that there was some suggestion of slight asymmetry (see Figure S1D under Supplemental data in the online issue for the plot), but the Egger s test for asymmetry was not significant (P =.6). An investigation into potential sources of heterogeneity by using meta-regression analysis showed no significant associations between estimates; factors explored included whether schools were randomized, not randomized, or not made clear; trial design (multi- of single-component); age of the children; type of dietary assessment; or length of follow-up (Table 2). However, there were nonsignificant trends in the pooled estimates for trial design. The pooled estimate for single-component studies was smaller, although heterogeneity was higher than for all studies combined. Five studies reported results for 2 followup periods. In 3 studies [ie, Ransley et al (52), Reynolds et al (75), and Baranowski et al (56)], the interventions continued beyond the first follow-up data-collection point. In 2 studies (58, 6), the final follow-up collection period was.3 mo after the completion of the intervention. Data reported at the latest follow-up period were used for each study. Quality of studies included in the meta-analyses The quality of the 22 trials included in the meta-analyses was generally poor with evidence of high risk of bias. One study reported on all 3 criteria and was, therefore, judged to be at low risk of bias (72). Ten studies reported on one or 2 criteria and were, therefore, judged to be at medium risk of bias (52, 55 57, 71, 73, 74, 76, 77, 8). The remaining 11 trials were judged to be at high risk of bias and did not clearly report sequencegeneration criteria, allocation concealment, or blinding of participants, personnel, or outcome assessors.

8 896 EVANS ET AL FIGURE 4. Pooled estimate of difference in daily portions of fruit consumed between intervention and control groups by using the longest follow-up data available and excluding studies that combined fruit and fruit juice. Weight was assigned with STATA version 11 software (StataCorp) by using n and SEM. Horizontal lines denote 95% CIs. The diamond represents the overall estimated effect. The meta-analysis used the weighted mean difference in the randomeffects model. ID, identification. DISCUSSION Main findings To our knowledge, this review provides the first meta-analysis to quantify the impact of a range of school-based interventions on the daily consumption of fruit and vegetables in children aged 5 12 y. It is also the first review to our knowledge to quantify the differences in impact on vegetable compared with fruit intake. School-based interventions of all types were estimated to improve daily fruit and vegetable consumption by an average of one-quarter to one-third of a portion (equivalent to a 2 3-g daily increase). Although most schemes aimed to improve intake of both fruit and vegetables, most schemes failed to increase vegetable intake by a useful amount, with most of the improvement made in fruit intake. Studies that included fruit juice when the consumption of fruit and vegetables was assessed tended to have a higher intake of fruit, juice, and vegetables at baseline and higher increases as a result of the intervention. The exclusion of fruit juice, which is not strongly associated with health outcomes, attenuated the impact of programs on daily fruit and vegetable intake. Comparison of different types of programs School-based interventions generally fall into the following 2 main categories: multicomponent programs that motivate and engage children and families to change their eating behaviors, and single-component programs that provide and distribute free or subsidized fruit and vegetables. In this review, multicomponent programs tended to result in larger improvements in fruit and vegetable intake but were diverse and could potentially be difficult to replicate without considerable time, manpower, and funds (48). How well interventions are implemented has been reported to determine the impact of a program (81, 82). Singlecomponent studies, including free and subsidized fruit- and vegetable-distribution schemes, tended to be less effective, although there were too few studies included to enable firm conclusions to be made. Distribution schemes have recently been introduced in some schools as part of national policies to increase children s fruit and vegetable intake. These schemes may offer little in terms of learned permanent improvement on children s eating habits; however, fruit and vegetable intake may be moderately improved when children receive fruit at school. Teachers who have rated programs for ease of use have rated distribution programs easier to implement than multicomponent programs (83); therefore, long-term distribution programs may be a useful option for governments. Comparisons with previous reviews Previous reviews that were based on qualitative analysis without a meta-analysis reported increases of 1 serving of fruit and vegetables per day (49, 5). The results obtained in this study were similar to those of a previous meta-analysis of 7 studies, which reported an increase of.4 portions of fruit and vegetables per day. This previous review included mainly multicomponent studies and did not exclude studies on the basis of including fruit juice, which may explain the slightly higher effect (51). A recent review of programs to improve fruit and vegetable intake stratified by type of intervention concluded that computer-based interventions were the most successful type of program, and multicomponent programs had no impact. This

9 REVIEW OF SCHOOL-BASED INTERVENTIONS 897 FIGURE 5. Pooled estimate of difference in daily portions of vegetables consumed between intervention and control groups by using the longest follow-up data available and including studies that combined fruit and fruit juice. Weight was assigned with STATA version 11 (StataCorp) by using n and SEM. Horizontal lines denote 95% CIs. The diamond represents the overall estimated effect. The meta-analysis used the weighted mean difference in the randomeffects model. ID, identification. conclusion was based on 2 analyses. First, a meta-analysis of only 2 programs that used computer games, one analysis of which did not include fruit and vegetable intake over the whole day (only the school day), and one analysis of which included fruit juice. Second, the conclusions were based on an analysis of 7 multicomponent programs, 6 programs of which improved fruit and vegetable intake, but because of high levels of heterogeneity as a result of including programs that measured only fruit or vegetable intake and programs that assessed fruit and vegetable intake over part of the day, it was not possible to make firm conclusions (47). In this review, it was established that there were currently not enough studies that assessed daily intake of fruit and vegetables to determine the impact of different types of studies, although we identified a trend that multicomponent studies were more effective than single-component studies. Strengths of this review This review had a number of strengths. A range of multi- and single-component programs were included from different countries. Robust review methods were used including the use of a range of databases to find articles from a variety of sources and the use of 2 reviewers to determine inclusions and exclusions. Furthermore, the formal quantification of pooled estimates was carried out by using a meta-analysis. Studies were included that reported the frequency of consumption of fruit and vegetables as well as standard portion sizes or weight in grams. Measures were taken to reduce heterogeneity by restricting the age group and including only studies in which standard methods of assessment were used. Fruit and vegetable intakes have been shown to be underestimated by some methods (84), but no substantial differences by assessment method were identified in this review. Studies that focused on obese children were excluded because those children may be expected to be more prepared to change their diet than are children in general. Limitations of this review The protocol was designed in 28 by using a Cochrane review protocol as a template, and all authors were involved in the design and agreement of the protocol. The protocol was unpublished until the completion of the review, which is suboptimal in a metaanalysis; however, the protocol is now published (see Supplemental data in the online issue). Many studies published in this area are of poor-quality design without a control group or with poor randomization methods that lead to biased reporting. The reporting of results was not consistent, and a number of studies did not report both fruit and vegetable consumption combined. Successful programs may not have been included in the analysis because of a lack of suitable published data on improvements in fruit and vegetable intake over the whole day. There was some evidence of publication bias as shown by the asymmetric funnel plots. This bias may have modestly overestimated

10 898 EVANS ET AL TABLE 2 Pooled effects of studies that excluded and included fruit juice on daily portions of fruit and vegetable consumption by subgroup analysis stratified by randomization method, study design, length of follow-up, type of dietary assessment, and age of children Variables No. of studies Pooled estimate (95% P-heterogeneity within CI) for subgroup I 2 subgroup P-heterogeneity between subgroups % Studies that excluded fruit juice Randomization.83 Randomized 4.26 (.12,.4) 1.39 Not randomized 4.26 (2.17,.69) 69.2 Unclear 3.35 (2.28,.98) 68.4 Study design.47 Multicomponent 8.29 (.8,.49) 4.11 Single component 3.15 (2.26,.56) 67.5 Length of follow-up.9 2 school years 6.26 (.5,.47) school year 3.8 (2.29,.46) 48.15,1 school year 2.72 (.14, 1.3).53 Type of dietary assessment h recall 5.46 (.7,.86) 54.7 Unweighed diary 3.8 (2.29,.46) FFQ (.8,.4) Mean age of children 16.2 (2.7,.11).68 Sample size (per 1) (2.6, 2.1).49 Studies that included fruit juice Randomization.4 Randomized 5.24 (.12,.35).51 Not randomized 5.33 (2.13,.8) 67.1 Unclear 4.54 (2.4, 1.12) 78,.1 Study design.48 Multicomponent 1.36 (.16,.56) 62.1 Single component 4.22 (2.25,.7) 68.3 Length of follow-up.88 2 school years 8.33 (.12,.54) school year 3.8 (2.29,.46) 48.15,1 school year 3.82 ( ) 1.33 Type of dietary assessment h recall 6.58 (.2,.96) 64.2 Unweighed diary 4.12 (2.11,.35) FFQ 4.22 (2.2,.46) Mean age of children 2.1 (2.95,.11).86 Sample size (per 1) (2.3,.1).44 1 FFQ, food-frequency questionnaire. the magnitude of the results but was unlikely to have substantially altered the overall conclusions provided in this article. Future strategies Some components from earlier multicomponent programs have been incorporated into national policy in some countries. For example, the curriculum in many countries includes specific lessons on healthy eating (85). In the United Kingdom, children aged 4 7 y receive free fruit and vegetables and a school meal that meets food-based standards that include daily fruit and vegetable provision, both of which are elements of recent multicomponent programs. However, there are some areas in which very few or no trials have been reported in this age group, such as studies in which cooking or school gardening is the main component (86). Some types of studies, such as the tasting of fruit and vegetables, were not included in the review because of a lack of assessment of daily fruit and vegetable intake in these mainly laboratory-based studies (87); however, exposing children who disliked vegetables for 14 d has been reported to increase liking and the consumption of vegetables (88). There is also evidence that schools that participate in gardening programs increase fruit and vegetable, vitamin A, vitamin C, and fiber intakes (89). Future randomized controlled trials in these areas may be expected to further contribute to an increase in the intake of vegetables in particular, which is badly needed. There should also be a focus on families and home consumption of fruit and vegetables. Very few studies collected follow-up data a full year after the intervention, particularly if the intervention was,6 mo in duration. Studies that did collect this type of data saw a moderate long-term impact on fruit and vegetable intake (6), which indicated that, if intervention programs are to have an impact on the health of children, the programs must run continuously over long periods of time and should not be considered as one-off solutions. On the basis of these results, school-based programs could be expected to increase fruit and vegetable intake by onequarter to one-third of a portion, but there is limited evidence of

11 REVIEW OF SCHOOL-BASED INTERVENTIONS 899 the impact on future health outcomes from a daily increase of one-third of a portion of fruit and vegetables at a population level. In conclusion, school-based programs, including distribution schemes, have the potential to moderately improve the daily consumption of fruit. However these programs do not appear to be successful at improving vegetable intake in schoolchildren. More efforts are needed to design programs to improve vegetable intake in children and to reduce barriers to positive behavior change. We are grateful to Camilla Nykjaer for checking data. The authors responsibilities were as follows CELE: put forth the initial idea to carry out the review, contributed to the searching, analyzed data by using a meta-analysis, wrote the first draft of the manuscript, and contributed to the subsequent drafts of the manuscript; MSC: was involved in producing the original search criteria and the searching of articles and contributed to all drafts of the manuscript; CLC: managed the search database, determined trial quality, and contributed to all drafts of the manuscript; DCG: provided essential statistical support for all analysis and contributed to all drafts of the manuscript; and JEC: provided essential support at all stages of the review and contributed to all drafts of the manuscript. None of the authors had a conflict of interest. REFERENCES 1. Bazzano LA, He J, Ogden LG, Loria CM, Vupputuri S, Myers L, Whelton PK. Fruit and vegetable intake and risk of cardiovascular disease in US adults: the first National Health and Nutrition Examination Survey Epidemiologic Follow-up Study. Am J Clin Nutr 22; 76: Boffetta P, Couto E, Wichmann J, Ferrari P, Trichopoulos D, Buenode-Mesquita HB, van Duijnhoven FJ, Buchner FL, Key T, Boeing H, et al. Fruit and vegetable intake and overall cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC). J Natl Cancer Inst 21;12: Lunet N, Lacerda-Vieira A, Barros H. Fruit and vegetables consumption and gastric cancer: a systematic review and meta-analysis of cohort studies. Nutr Cancer 25;53: Steinmetz KA, Potter JD. Vegetables, fruit, and cancer prevention: a review. J Am Diet Assoc 1996;96: Dauchet L, Amouyel P, Hercberg S, Dallongeville J. fruit and vegetable consumption and risk of coronary heart disease: a meta-analysis of cohort studies. J Nutr 26;136: Ness AR, Powles JW. Fruit and vegetables, and cardiovascular disease: a review. Int J Epidemiol 1997;26: Bazzano LA, Li TY, Joshipura KJ, Hu FB. Intake of fruit, vegetables, and fruit juices and risk of diabetes in women. Diabetes Care 28;31: Harding AH, Wareham NJ, Bingham SA, Khaw K, Luben R, Welch A, Forouhi NG. Plasma vitamin C level, fruit and vegetable consumption, and the risk of new-onset type 2 diabetes mellitus: the European prospective investigation of cancer Norfolk prospective study. Arch Intern Med 28;168: Liu S, Serdula M, Janket SJ, Cook NR, Sesso HD, Willett WC, Manson JE, Buring JE. A prospective study of fruit and vegetable intake and the risk of type 2 diabetes in women. Diabetes Care 24;27: Appel LJ, Moore TJ, Obarzanek E, Vollmer WM, Svetkey LP, Sacks FM, Bray GA, Vogt TM, Cutler JA, Windhauser MM, et al. A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. N Engl J Med 1997;336: Miura K, Greenland P, Stamler J, Liu K, Daviglus ML, Nakagawa H. Relation of vegetable, fruit, and meat intake to 7-year blood pressure change in middle-aged men: the Chicago Western Electric Study. Am J Epidemiol 24;159: WHO. Diet, nutrition and the prevention of chronic diseases. In: FAO, ed. Geneva, Switzerland: World Health Organization; He K, Hu FB, Colditz GA, Manson JE, Willett WC, Liu S. Changes in intake of fruits and vegetables in relation to risk of obesity and weight gain among middle-aged women. Int J Obes Relat Metab Disord 24; 28: Newby PK. Plant foods and plant-based diets: protective against childhood obesity? Am J Clin Nutr 29;89:1572S 87S. 15. Ledoux TA, Hingle MD, Baranowski T. Relationship of fruit and vegetable intake with adiposity: a systematic review. Obes Rev 211; 12:e Andersen LF, Overby N, Lillegaard IT. Intake of fruit and vegetables among Norwegian children and adolescents Tidsskr Nor Laegeforen 24;124: (in Norwegian). 17. McCrory MA, Fuss PJ, McCallum JE, Yao M, Vinken AG, Hays NP, Roberts SB. Dietary variety within food groups: association with energy intake and body fatness in men and women. Am J Clin Nutr 1999;69: Rolls BJ, Ello-Martin JA, Tohill BC. What can intervention studies tell us about the relationship between fruit and vegetable consumption and weight management? Nutr Rev 24;62: Pomerleau J, McKee M, Lobstein T, Knai C. The burden of disease attributable to nutrition in Europe. Public Health Nutr 23;6: Maynard M, Gunnell D, Ness AR, Abraham L, Bates CJ, Blane D. What influences diet in early old age? Prospective and cross-sectional analyses of the Boyd Orr cohort. Eur J Public Health 26;16: Vereecken CA, De Henauw S, Maes L. Adolescents food habits: results of the Health Behaviour in School-aged Children survey. Br J Nutr 25;94: Rogers IS, Ness AR, Hebditch K, Jones LR, Emmett PM. Quality of food eaten in English primary schools: school dinners vs packed lunches. Eur J Clin Nutr 27;61: Baxter IA, Schroder MJA. Vegetable consumption among Scottish children: a review of the determinants and proposed strategies to overcome low consumption. Br Food J 1997;99: Krebs-Smith SM, Cook A, Subar AF, Cleveland L, Friday J, Kahle LL. Fruit and vegetable intakes of children and adolescents in the United States. Arch Pediatr Adolesc Med 1996;15: Timperio A, Ball K, Roberts R, Campbell K, Andrianopoulos N, Crawford D. Children s fruit and vegetable intake: associations with the neighbourhood food environment. Prev Med 28;46: Magarey A, Daniels LA, Smith A. Fruit and vegetable intakes of Australians aged 2-18 years: an evaluation of the 1995 National Nutrition Survey data. Aust N Z J Public Health 21;25: Cockroft JE, Durkin M, Masding C, Cade JE. Fruit and vegetable intakes in a sample of pre-school children participating in the Five for All project in Bradford. Public Health Nutr 25;8: Gregory J, Lowe S, Bates CJ, Prentice AM, Jackson LV, Smithers G, Wenlock RW, Farron M. National Diet and Nutrition Survey (NDNS): young people aged 4 to 18 years. London, United Kingdom: the Stationery Office, Muñoz de Chávez M, Chávez A. Diet that prevents cancer: recommendations from the American Institute for Cancer Research. Int J Cancer Suppl 1998;11: Department of Health. 5 A Day live well NHS choices; 25. Available from: De Bourdeaudhuij I, te Velde S, Brug J, Due P, Wind M, Sandvik C, Maes L, Wolf A, Perez Rodrigo C, Yngve A, et al. Personal, social and environmental predictors of daily fruit and vegetable intake in 11-yearold children in nine European countries. Eur J Clin Nutr 28;62: Hanson NI, Neumark-Sztainer D, Eisenberg ME, Story M, Wall M. Associations between parental report of the home food environment and adolescent intakes of fruits, vegetables and dairy foods. Public Health Nutr 25;8: Blanchette L, Brug J. Determinants of fruit and vegetable consumption among 6-12-year-old children and effective interventions to increase consumption. J Hum Nutr Diet 25;18: Brug J, Tak NI, te Velde SJ, Bere E, de Bourdeaudhuij I. Taste preferences, liking and other factors related to fruit and vegetable intakes among schoolchildren: results from observational studies. Br J Nutr 28;99(suppl 1):S Gibson EL, Wardle J, Watts CJ. Fruit and vegetable consumption, nutritional knowledge and beliefs in mothers and children. Appetite 1998;31: Kratt P, Reynolds K, Shewchuk R. The role of availability as a moderator of family fruit and vegetable consumption. Health Educ Behav 2;27: Neumark-Sztainer D, Wall M, Perry C, Story M. Correlates of fruit and vegetable intake among adolescents. Findings from Project EAT. Prev Med 23;37:

12 9 EVANS ET AL 38. Weber Cullen K, Baranowski T, Rittenberry L, Cosart C, Owens E, Hebert D, de Moor C. Socioenvironmental influences on children s fruit, juice and vegetable consumption as reported by parents: reliability and validity of measures. Public Health Nutr 2;3: Galloway AT, Lee Y, Birch LL. Predictors and consequences of food neophobia and pickiness in young girls. J Am Diet Assoc 23;13: Pearson N, Biddle SJ, Gorely T. Family correlates of fruit and vegetable consumption in children and adolescents: a systematic review. Public Health Nutr 29;12: Kloek GC, van Lenthe FJ, van Nierop PW, Mackenbach JP. Stages of change for fruit and vegetable consumption in deprived neighborhoods. Health Educ Behav 24;31: Johansson L, Thelle DS, Solvoll K, Bjorneboe GE, Drevon CA. Healthy dietary habits in relation to social determinants and lifestyle factors. Br J Nutr 1999;81: Thompson RL, Margetts BM, Speller VM, McVey D. The Health Education Authority s health and lifestyle survey 1993: who are the low fruit and vegetable consumers? J Epidemiol Community Health 1999;53: Pollard J, Greenwood D, Kirk S, Cade J. Motivations for fruit and vegetable consumption in the UK Women s Cohort Study. Public Health Nutr 22;5: Vereecken CA, Keukelier E, Maes L. Influence of mother s educational level on food parenting practices and food habits of young children. Appetite 24;43: Baranowski T, Smith M, Hearn MD, Lin LS, Baranowski J, Doyle C, Resnicow K, Wang DT. Patterns in children s fruit and vegetable consumption by meal and day of the week. J Am Coll Nutr 1997;16: Delgado-Noguera M, Tort S, Martinez-Zapata MJ, Bonfill X. Primary school interventions to promote fruit and vegetable consumption: a systematic review and meta-analysis. Prev Med 211;53: Van Cauwenberghe E, Maes L, Spittaels H, van Lenthe FJ, Brug J, Oppert JM, De Bourdeaudhuij I. Effectiveness of school-based interventions in Europe to promote healthy nutrition in children and adolescents: systematic review of published and grey literature. Br J Nutr 21;13: Knai C, Pomerleau J, Lock K, McKee M. Getting children to eat more fruit and vegetables: a systematic review. Prev Med 26;42: French SA, Stables G. Environmental interventions to promote vegetable and fruit consumption among youth in school settings. Prev Med 23;37: Howerton MW, Bell BS, Dodd KW, Berrigan D, Stolzenberg-Solomon R, Nebeling L. School-based nutrition programs produced a moderate increase in fruit and vegetable consumption: meta and pooling analyses from 7 studies. J Nutr Educ Behav 27;39: Ransley JK, Greenwood DC, Cade JE, Blenkinsop S, Schagen I, Teeman D, Scott E, White G, Schagen S. Does the school fruit and vegetable scheme improve children s diet? A non-randomised controlled trial. J Epidemiol Community Health 27;61: Egger M, Davey Smith G, Altman DG, eds. systematic reviews in healthcare: meta-analysis in context. 2nd ed. London, United Kingdom: BMJ Books; Higgins JPT, Thompson SG, Deeks JJ, Altman DG. Measuring inconsistency in meta-analyses. BMJ 23;327: Anderson AS, Porteous L, Foster E, Higgins C, Stead M, Hetherington M, Ha M-A, Adamson A. The impact of a school-based nutrition education intervention on dietary intake and cognitive and attitudinal variables relating to fruits and vegetables. Public Health Nutr 25;8: Baranowski T, Davis M, Resnicow K, Baranowski J, Doyle C, Lin LS, Smith M, Wang DT. Gimme 5 fruit, juice, and vegetables for fun and health: outcome evaluationhealth Educ Behav 2;27: (Published erratum appears in Health Educ Behav 2;27:39.) 57. Baranowski T, Baranowski J, Cullen KW, Marsh T, Islam N, Zakeri I, Honess-Morreale L, demoor C. Squire s Quest! Dietary outcome evaluation of a multimedia game. Am J Prev Med 23;24: Bere E, Veierod MB, Klepp KI. The Norwegian School Fruit Programme: evaluating paid vs. no-cost subscriptions. Prev Med 25;41: Bere E, Veierod MB, Bjelland M, Klepp KI. Free school fruit sustained effect 1 year later. Health Educ Res 26;21: Bere E, Veierod MB, Bjelland M, Klepp KI. Outcome and process evaluation of a Norwegian school-randomized fruit and vegetable intervention: Fruits and Vegetables Make the Marks (FVMM). Health Educ Res 26;21: Day ME, Strange K, McKay H, Naylor P. Action Schools! BC Healthy Eating: effects of a whole-school model to modifying eating behaviours of elementary school children. Can J Public Health 28;99: Eriksen K, Haraldsdottir J, Pederson R, Flyger HV, Eriksen K, Haraldsdottir J, Pederson R, Flyger HV. Effect of a fruit and vegetable subscription in Danish schools. Public Health Nutr 23;6: Foerster SB, Gregson J, Beall D, Lane M, Hudes M, Magnuson H, Livingston S, Davis MA, Block JA, Garbolino T. The California Children s 5 a Day- Power Play! Campaign: evaluation of a large-scale social marketing initiative. Fam Community Health 1998;21: Fogarty AW, Antoniak M, Venn A, Davies L, Goodwin A, Salfield N, Stocks J, Britton J, Lewis S. Does participation in a population-based dietary intervention scheme have a lasting impact on fruit intake in young children? Int J Epidemiol 27;36: Foster GD, Sherman S, Borradaile KE, Grundy KM, Vander Veur SS, Nachmani J, Karpyn A, Kumanyika S, Shults J. A policy-based school intervention to prevent overweight and obesity. Pediatrics 28;121: e Gortmaker SL, Cheung LW, Peterson KE, Chomitz G, Cradle JH, Dart H, Fox MK, Bullock RB, Sobol AM, Colditz G, et al. Impact of a school-based interdisciplinary intervention on diet and physical activity among urban primary school children: eat well and keep moving. Arch Pediatr Adolesc Med 1999;153: Gortmaker SL, Peterson K, Wiecha J, Sobol AM, Dixit S, Fox MK, Laird N. Reducing obesity via a school-based interdisciplinary intervention among youth: Planet Health. Arch Pediatr Adolesc Med 1999;153: Govula C. culturally appropriate nutrition lessons increased fruit and vegetable consumption in American Indian children. Topics Clin Nutr 27;22: Hopper CA, Munoz KD, Gruber MB, MacConnie SE, Schonfeldt B, Shunk T. A school-based cardiovascular exercise and nutrition program with parent participation: An evaluation study. Child Health Care 1996; 25: Lowe CF, Horne PJ, Tapper K, Bowdery M, Egerton C. Effects of a peer modelling and rewards-based intervention to increase fruit and vegetable consumption in children. Eur J Clin Nutr 24;58: Mangunkusumo RT, Brug J, de Koning HJ, van der Lei J, Raat H. School-based Internet-tailored fruit and vegetable education combined with brief counselling increases children s awareness of intake levels. Public Health Nutr 27;1: Moore L, Tapper K. The impact of school fruit tuck shops and school food policies on children s fruit consumption: a cluster randomised trial of schools in deprived areas. J Epidemiol Community Health 28;62: Perry CL, Bishop DB, Taylor G, Murray DM, Mays RW, Dudovitz BS, Smyth M, Story M. Changing fruit and vegetable consumption among children: the 5-a-Day Power Plus program in St. Paul, Minnesota. Am J Public Health 1998;88: Reinaerts E, Crutzen R, Candel M, De Vries NK, De Nooijer J. Increasing fruit and vegetable intake among children: comparing longterm effects of a free distribution and a multicomponent program. Health Educ Res 28;23: Reynolds KD, Franklin FA, Binkley D, Raczynski JM, Harrington KF, Kirk KA, Person S. Increasing the fruit and vegetable consumption of fourth-graders: results from the high 5 project. Prev Med 2;3: Sahota P, Rudolf MC, Dixey R, Hill AJ, Barth JH, Cade J. Randomised controlled trial of primary school based intervention to reduce risk factors for obesity. BMJ 21;323: Spiegel SA, Foulk D. Reducing overweight through a multidisciplinary school-based intervention. Obesity (Silver Spring) 26;14: Tak NI, te Velde SJ, Brug J. Ethnic differences in 1-year follow-up effect of the Dutch Schoolgruiten Project? Promoting fruit and vegetable consumption among primary-school children. Public Health Nutr 27;1: Taylor RW, McAuley KA, Barbezat W, Strong A, Williams SM, Mann JI. APPLE Project: 2-y findings of a community-based obesity prevention program in primary school age children. Am J Clin Nutr 27; 86: Reinaerts E, de Nooijer J, Candel M, de Vries N. Increasing children s fruit and vegetable consumption: distribution or a multicomponent programme? Public Health Nutr 27;1: