A cluster randomised controlled trial of a sugar-sweetened beverage intervention in secondary schools: Pilot study protocol

Effectiveness of nutrition interventions in Australian secondary schools: A systematic review

ISSUE ADDRESSED

Dietary intake of Australian adolescents is suboptimal. Schools are an ideal setting for health promotion initiatives to develop healthy lifestyle behaviours among adolescents. However, we do not know which nutrition-focused, school-based interventions are effective at improving health outcomes in adolescents in Australia. Therefore, the aim was to evaluate the effect of nutrition interventions on health outcomes in Australian secondary school students.

METHODS

MEDLINE, EMBASE, CINAHL, ERIC and Informit were systematically searched on 4th November 2022. Studies in any language evaluating nutrition interventions implemented in Australian secondary schools were included. Studies evaluating interventions conducted in primary schools or outside the school setting were excluded, as were any grey literature, systematic reviews and meta-analyses. Screening and data extraction were performed in duplicate. Quality was assessed using the Mixed Methods Appraisal Tool.

RESULTS

Thirteen studies (n = 27 224) reporting on nutrition interventions implemented in Australian secondary schools were included. Studies were conducted in five different states and a capital territory within Australia and were mostly randomised controlled trials. Most studies reported a significant improvement on nutrition-related health outcome measures (dietary behaviour n = 6, nutritional knowledge and attitudes n = 4 and anthropometric n = 1).

CONCLUSIONS

This review found limited studies reporting on nutrition interventions in Australian secondary schools. However, most were shown to be effective in improving nutrition-related health outcomes. SO WHAT?: Since there were limited studies in peer-reviewed journals, more research in this area is needed to confirm the effectiveness of nutrition interventions in Australian secondary schools and to assess long-term effects on student's health outcomes.

Interventions to prevent obesity in children aged 12 to 18 years old

BACKGROUND

Prevention of obesity in adolescents is an international public health priority. The prevalence of overweight and obesity is over 25% in North and South America, Australia, most of Europe, and the Gulf region. Interventions that aim to prevent obesity involve strategies that promote healthy diets or 'activity' levels (physical activity, sedentary behaviour and/or sleep) or both, and work by reducing energy intake and/or increasing energy expenditure, respectively. There is uncertainty over which approaches are more effective, and numerous new studies have been published over the last five years since the previous version of this Cochrane Review.

OBJECTIVES

To assess the effects of interventions that aim to prevent obesity in adolescents by modifying dietary intake or 'activity' levels, or a combination of both, on changes in BMI, zBMI score and serious adverse events.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was February 2023.

SELECTION CRITERIA

Randomised controlled trials in adolescents (mean age 12 years and above but less than 19 years), comparing diet or 'activity' interventions (or both) to prevent obesity with no intervention, usual care, or with another eligible intervention, in any setting. Studies had to measure outcomes at a minimum of 12 weeks post baseline. We excluded interventions designed primarily to improve sporting performance.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our outcomes were BMI, zBMI score and serious adverse events, assessed at short- (12 weeks to < 9 months from baseline), medium- (9 months to < 15 months) and long-term (≥ 15 months) follow-up. We used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

This review includes 74 studies (83,407 participants); 54 studies (46,358 participants) were included in meta-analyses. Sixty studies were based in high-income countries. The main setting for intervention delivery was schools (57 studies), followed by home (nine studies), the community (five studies) and a primary care setting (three studies). Fifty-one interventions were implemented for less than nine months; the shortest was conducted over one visit and the longest over 28 months. Sixty-two studies declared non-industry funding; five were funded in part by industry. Dietary interventions versus control The evidence is very uncertain about the effects of dietary interventions on body mass index (BMI) at short-term follow-up (mean difference (MD) -0.18, 95% confidence interval (CI) -0.41 to 0.06; 3 studies, 605 participants), medium-term follow-up (MD -0.65, 95% CI -1.18 to -0.11; 3 studies, 900 participants), and standardised BMI (zBMI) at long-term follow-up (MD -0.14, 95% CI -0.38 to 0.10; 2 studies, 1089 participants); all very low-certainty evidence. Compared with control, dietary interventions may have little to no effect on BMI at long-term follow-up (MD -0.30, 95% CI -1.67 to 1.07; 1 study, 44 participants); zBMI at short-term (MD -0.06, 95% CI -0.12 to 0.01; 5 studies, 3154 participants); and zBMI at medium-term (MD 0.02, 95% CI -0.17 to 0.21; 1 study, 112 participants) follow-up; all low-certainty evidence. Dietary interventions may have little to no effect on serious adverse events (two studies, 377 participants; low-certainty evidence). Activity interventions versus control Compared with control, activity interventions do not reduce BMI at short-term follow-up (MD -0.64, 95% CI -1.86 to 0.58; 6 studies, 1780 participants; low-certainty evidence) and probably do not reduce zBMI at medium- (MD 0, 95% CI -0.04 to 0.05; 6 studies, 5335 participants) or long-term (MD -0.05, 95% CI -0.12 to 0.02; 1 study, 985 participants) follow-up; both moderate-certainty evidence. Activity interventions do not reduce zBMI at short-term follow-up (MD 0.02, 95% CI -0.01 to 0.05; 7 studies, 4718 participants; high-certainty evidence), but may reduce BMI slightly at medium-term (MD -0.32, 95% CI -0.53 to -0.11; 3 studies, 2143 participants) and long-term (MD -0.28, 95% CI -0.51 to -0.05; 1 study, 985 participants) follow-up; both low-certainty evidence. Seven studies (5428 participants; low-certainty evidence) reported data on serious adverse events: two reported injuries relating to the exercise component of the intervention and five reported no effect of intervention on reported serious adverse events. Dietary and activity interventions versus control Dietary and activity interventions, compared with control, do not reduce BMI at short-term follow-up (MD 0.03, 95% CI -0.07 to 0.13; 11 studies, 3429 participants; high-certainty evidence), and probably do not reduce BMI at medium-term (MD 0.01, 95% CI -0.09 to 0.11; 8 studies, 5612 participants; moderate-certainty evidence) or long-term (MD 0.06, 95% CI -0.04 to 0.16; 6 studies, 8736 participants; moderate-certainty evidence) follow-up. They may have little to no effect on zBMI in the short term, but the evidence is very uncertain (MD -0.09, 95% CI -0.2 to 0.02; 3 studies, 515 participants; very low-certainty evidence), and they may not reduce zBMI at medium-term (MD -0.05, 95% CI -0.1 to 0.01; 6 studies, 3511 participants; low-certainty evidence) or long-term (MD -0.02, 95% CI -0.05 to 0.01; 7 studies, 8430 participants; low-certainty evidence) follow-up. Four studies (2394 participants) reported data on serious adverse events (very low-certainty evidence): one reported an increase in weight concern in a few adolescents and three reported no effect.

AUTHORS' CONCLUSIONS

The evidence demonstrates that dietary interventions may have little to no effect on obesity in adolescents. There is low-certainty evidence that activity interventions may have a small beneficial effect on BMI at medium- and long-term follow-up. Diet plus activity interventions may result in little to no difference. Importantly, this updated review also suggests that interventions to prevent obesity in this age group may result in little to no difference in serious adverse effects. Limitations of the evidence include inconsistent results across studies, lack of methodological rigour in some studies and small sample sizes. Further research is justified to investigate the effects of diet and activity interventions to prevent childhood obesity in community settings, and in young people with disabilities, since very few ongoing studies are likely to address these. Further randomised trials to address the remaining uncertainty about the effects of diet, activity interventions, or both, to prevent childhood obesity in schools (ideally with zBMI as the measured outcome) would need to have larger samples.

A systematic review of educational nutrition interventions based on behavioral theories in school adolescents

The purpose of this study was to summarize the evidence from studies conducted on adolescents, evaluating educational nutrition interventions for the modification of food consumption through controlled trials based on behavior change theories or models and implemented in school settings. A systematic search was carried out through PubMed and ERIC databases between November and December 2020, and updated in February 2023; English-language keywords were used, and no publication date limits were applied. Two authors independently performed the search, data extraction, data synthesis and risk of bias assessment. Twelve studies meeting the inclusion criteria were included. The interventions were based on different theories; the most used was the Social Cognitive Theory. Eleven of the twelve studies showed favorable modifications in the consumption of at least two of the food groups. Most studies were at low risk of bias, and only one was classified as high risk. It is concluded that educational nutrition interventions based on behavior change theories/models and implemented in the school setting influence positive changes in adolescents eating behavior.

A trial of a six-month sugar-sweetened beverage intervention in secondary schools from a socio-economically disadvantaged region in Australia

OBJECTIVE

This study assessed the effectiveness of a school-based intervention in reducing adolescents' sugar-sweetened beverage (SSB) consumption and percentage of energy from SSBs. Secondary outcomes were SSB consumption within school, average daily energy intake, and body mass index z-scores.

METHODS

Six secondary schools located in New South Wales, Australia were recruited to participate in a six-month pilot randomised controlled trial (1:1). The intervention included components targeting the school nutrition environment, curricula and community. Outcomes were collected via online surveys, observations, anthropometric measurements and project records. Between-group differences were assessed via linear mixed models.

RESULTS

At the six-month intervention endpoint (n=862) there were no statistically significant differences between students in intervention or control schools for mean daily intake of SSBs (8.55mL; CI -26.77, 43.87; p=0.63), percentage daily energy from SSBs (0.12% kJ; CI -0.55, 0.80; p=0.72), or for secondary outcomes. Acceptability of the school-based strategies were high, however intervention fidelity varied across schools.

CONCLUSION

While acceptable, improving fidelity of implementation and increasing the duration or intensity of the intervention may be required to reduce SSB intake. Implications for public health: Engaging parents and education stakeholders in the development phase to co-design interventions may prove beneficial in improving intervention fidelity and enhance behavioural outcomes.

A cluster randomised controlled trial of a secondary school intervention to reduce intake of sugar-sweetened beverages: Mid-intervention impact of switchURsip environmental strategies

ISSUE ADDRESSED

Secondary schools provide an opportune setting for interventions addressing excessive sugar-sweetened beverage (SSB) intake in adolescence. This trial aimed to assess the impact of school environmental strategies, delivered as part of a broader intervention, among Year 7-9 students' SSB consumption.

METHODS

Between March and July 2018, we conducted a cluster randomised controlled trial with 862 students attending six secondary schools (3 intervention and 3 control) in New South Wales. The intervention targeted SSB availability, placement, promotion and pricing, and increased availability and promotion of water. Control schools followed their usual programmes. Primary outcomes included mean daily SSB consumption (millilitres) and mean daily percentage energy from SSB (kilojoules). Sub-group analysis explored primary outcomes for gender, school year level and frequency of canteen use.

RESULTS

Of the 2265 eligible students, 1092 (50.2%) provided active parental consent and 940 (86.0%) participated in baseline data collection. No significant differences were observed between groups at follow-up for mean daily SSBs consumed (-10.17 mL, CI: -24.78; 45.12, P = 0.57) or mean daily percentage energy from SSBs (-0.20%, CI: -0.87; 0.47, P = .56). Significant effects were observed among girls in intervention compared to girls in control schools for mean daily SSB consumption (-52.02 mL, CI 99.8; 94.14, P = .03) and mean daily percentage of energy from SSBs (-0.90%, CI: -1.82; 0.02, P = .05).

CONCLUSIONS

At 3-month mid-intervention evaluation, the intervention failed to impact on mean daily consumption and mean percentage energy from SSBs, overall. However, an intervention effect was observed in girls. The limited overall effect is likely due to inadequate intervention dose related to the short duration, limiting opportunities for schools to fully implement the environmental strategies. SO WHAT?: A longer intervention duration with additional implementation support to allow adequate time to embed the strategies within the school is recommended. Implementation support strategies would ensure staff are supported throughout the process.

Environmental Interventions to Reduce the Consumption of Sugar-Sweetened Beverages: Abridged Cochrane Systematic Review

BACKGROUND

Regular consumption of sugar-sweetened beverages (SSB) can increase the risk for obesity, type 2 diabetes, cardiovascular disease, and dental caries. Interventions that alter the physical or social environment in which individuals make beverage choices have been proposed to reduce the consumption of SSB.

METHODS

We included randomised controlled, non-randomised controlled, and interrupted time series studies on environmental interventions, with or without behavioural co-interventions, implemented in real-world settings, lasting at least 12 weeks, and including at least 40 individuals. Studies on the taxation of SSB were not included, as these are subject of a separate Cochrane review. We used standard Cochrane methods for data extraction, risk of bias assessment, and evidence grading and synthesis. Searches were updated to January 24, 2018.

RESULTS

We identified 14,488 unique records and assessed 1,030 full texts for eligibility. We included 58 studies comprising a total of 1,180,096 participants and a median length of follow-up of 10 months. We found moderate-certainty evidence for consistent associations with decreases in SSB consumption or sales for the following interventions: traffic light labelling, price increases on SSB, in-store promotion of healthier beverages in supermarkets, government food benefit programs with incentives for purchasing fruits and vegetables and restrictions on SSB purchases, multi-component community campaigns focused on SSB, and interventions improving the availability of low-calorie beverages in the home environment. For the remaining interventions we found low- to very-low-certainty evidence for associations showing varying degrees of consistency.

CONCLUSIONS

With observed benefits outweighing observed harms, we suggest that environmental interventions to reduce the consumption of SSB be considered as part of a wider set of measures to improve population-level nutrition. Implementation should be accompanied by evaluations using appropriate methods. Future studies should examine population-level effects of interventions suitable for large-scale implementation, and interventions and settings not yet studied thoroughly.