Comparing the impact and mechanistic pathways of micro-environmental interventions targeting healthier vs. more environmentally sustainable food options: an overview of reviews

Background: The potential for interventions that target food environments to influence dietary behaviour has been explored for both healthier and more environmentally sustainable diets, but the extent to which health-focused and sustainability-focused interventions can inform each other is unclear. This overview of reviews compares the characteristics and effectiveness of micro-environmental interventions aimed at health versus sustainability and explores their mediators and moderators. Methods: We searched 10 databases for systematic reviews including randomised controlled trials of micro-environmental interventions targeting healthier or more sustainable food choices. We conducted forwards and backwards citation tracking of included reviews. Review quality was assessed using AMSTAR2. We narratively synthesised results, categorising interventions using the TIPPME typology of micro-environmental interventions. Results: We screened 4154 records and included 31 reviews, of which 26 targeted health and 5 sustainability. Of 228 interventions, 31 (13.6%) targeted sustainability, 194 (85.1%) targeted health, and 3 (1.3%) targeted both. There was little overlap between the intervention types investigated by health and sustainability interventions. Size and position interventions were most common for health interventions, whilst information and presentation interventions were the most frequent sustainability interventions. Default, size, and menu positioning interventions appear particularly promising for both health and sustainability benefits, albeit with limited evidence for the latter in particular. Evidence of effect modifiers was scarce. Almost all reviews had a “critically low” or “low” confidence rating based on the AMSTAR2, limiting confidence in their estimates of intervention effectiveness. Conclusions: There is more evidence for health-focused interventions than sustainability-focused interventions. Size and position interventions seem most promising, but evidence for sustainability is scarce. There is currently no evidence of differential responding to health vs. sustainability interventions, although we were unable to comprehensively assess this. More comparable evidence, and evidence on underlying mechanisms, is needed, prioritising the most effective interventions.