What makes interventions aimed at improving dietary behaviours successful in the secondary school environment? A systematic review of systematic reviews

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.

Toward Sustainable Diets-Interventions and Perceptions Among Adolescents: A Scoping Review

Adolescence is an important life stage during which shifts toward more healthy and sustainable diets can be promoted. Adolescents have increasing influence over their food choices, informed by their developing personal knowledge and values, affecting long-term dietary behaviors into adulthood. The recent literature regarding adolescents' (1) perceptions of environmentally sustainable diets and (2) interventions to support adolescents to eat sustainably was reviewed in this study. We reviewed published literature that focused on adolescent participants and their perceptions of, or interventions to support, sustainable dietary habits. Five electronic databases were searched to include studies published since 2012 that met the inclusion criteria, including reporting of participants aged between 11 and 18 years, reporting on adolescents' perceptions of sustainable diets or interventions implemented to improve the sustainability of adolescents' diets, and framed in the context of sustainability. Data were extracted, including study and participant characteristics, methodology, and results in relation to each of the 2 research focus areas. Twenty-eight articles were included in the review. Findings suggest that adolescents' understanding of what constitutes sustainable eating is poor. Adolescents who had previously received education regarding sustainable diets valued nature and health, or were from a rural or indigenous community, were more likely to value environmentally sustainable-food choices. Interventions which target adolescents' understanding of and aspiration to make sustainable-food choices appears to improve their attitudes toward sustainable food, whereas interventions to increase the availability of sustainable foods improved the environmental sustainability of adolescents' dietary intake. Multicomponent, tailored, and community-based interventions were most effective; however, the long-term effect of these interventions remains unclear. More research is needed in low- and middle-income countries, with consideration of adolescents' level of autonomy in food choice in local food environments and the long-term effectiveness of interventions. Systematic Review Registration: Open Science Framework identifier osf.io/h3jz6.

Fruit and vegetable consumption as a preventative strategy for non-communicable diseases

A high intake of fruit and vegetables (FV) has consistently been associated with a reduced risk of a number of non-communicable diseases. This evidence base is largely from prospective cohort studies, with meta-analyses demonstrating an association between increased FV intake and reduced risk of both CHD and stroke, although the evidence is less certain for cancer and diabetes. Controlled intervention trials examining either clinical or intermediate risk factor endpoints are more scarce. Therefore, evidence that FV consumption reduces the risk of disease is so far largely confined to observational epidemiology, which is hampered by some methodological uncertainties. Although increased FV intake is promoted across all dietary guidelines, national surveys confirm that dietary intakes are suboptimal and are not increasing over time. A range of barriers to increasing FV intake exist, including economic, physical and behavioural barriers that must be considered when exploring potential opportunities to change this, considering the feasibility of different approaches to encourage increased FV consumption. Such interventions must include consideration of context, for example, challenges and uncertainties which exist with the whole food system.

Improving adolescents' dietary behaviours in the school-setting: challenges and opportunities

Adolescence is a critical time of physical, psychological and social development, and thus, optimal nutritional intakes are required during this life stage. Despite this, adolescence is recognised as a period of nutritional vulnerability, with many reportedly failing to meet current dietary guidelines. The school-setting presents a favourable environment to intervene and promote positive dietary behaviours and is also inclusive regardless of socio-economic status. However, a lack of consensus exists on how best to utilise schools to facilitate improvements in dietary behaviours among this age group. Whilst previous research has focused on identifying the factors motivating dietary choices within the school-setting, less is known on the optimum strategies to enhance these dietary choices which could positively contribute to the design of future interventions. It is reported that adolescents have good nutritional knowledge, although this does not appear to be a central consideration when making their dietary choices. Alternative factors at the individual (taste, visual appeal, familiarity, food quality, price, portion size, value for money, time/ convenience), social (peer influence), physical (product placement) and macro environment (food availability) levels have been frequently cited as important influences on adolescents' dietary choices in school. Although school-based interventions have shown potential in achieving positive dietary change among adolescents, more research is needed to determine the most effective methods in improving dietary behaviours in schools. This review summarises the key factors which influence adolescents' school-based dietary choices and the effectiveness of previously conducted interventions, identifying promising components for consideration when developing future dietary interventions within the school-setting.

A Qualitative Evaluation of Social Aspects of Sugar-Rich Food and Drink Intake and Parental Strategies for Reductions

Danish children have a much larger intake of sugar-rich foods and drinks than recommended. This study aimed to (1) explore social aspects and practices of pre-school children's intake of sugar-rich foods and drinks and (2) evaluate barriers and parental strategies to reduce their children's intake of sugar-rich foods and drinks employed in connection with the 3.5-month family-centred intervention trial 'Are you too sweet?'. Intervention components included communication of the recommended maximum intake and reduction strategies, supported by resources encouraging and facilitating behavioural changes. A random sample of families (n = 24) from intervention schools participated in post-intervention semi-structured interviews. A thematic content analysis was conducted, revealing three main domains of social practices: (1) 'family treats', including the weekly Danish concept 'Friday sweets', (2) 'everyday treats', such as sweet snacks in lunch packs, between-meals snacks and soft drink habits and (3) 'socialized treats', including treats at special occasions. Parents employed several strategies, most often substitution and portion-size reduction, but also limiting home availability. Families most frequently made changes that were easily adoptable and close to existing routines at home. In conclusion, the intervention components provided families with knowledge and strategies that facilitated behavioural changes towards reducing the intake of sugar-rich foods and drinks.