The effectiveness of mobile app-based interventions in nudging towards sustainable and healthy diets: a systematic review and meta-analysis

One third of all greenhouse gas emissions come from the way we produce and consume food, and current diets are insufficient to meet environmental and health goals. Given the ubiquity of smartphone usage, apps delivering effective, engaging nudges could be a scalable and promising solution. However, the complexity of apps makes it difficult for stakeholders to prioritise. This systematic review and meta-analysis assessed the effectiveness of mobile apps for promoting sustainable dietary consumption across five food groups.
Seven electronic databases (MEDLINE, EMBASE, PsycINFO, CINAHL, Global Health, GreenFILE, Web of Science) and two trial registries (Cochrane Trials and Clinicaltrials.gov) were systematically searched for interventional studies, characterised according to their use of strategies to facilitate behaviour change.
Fourteen of 5261 identified records were included, comprising 12 randomised controlled trials and two pre-post trials, with a total of 7826 participants and sample sizes ranging from 17 to 5062. Five studies recruited the general population, three recruited students, and six recruited overweight or obese adults, three of which targeted lower socioeconomic groups. Interventions lasted from three days to 24 weeks, with the most common strategy being self-monitoring, followed by messaging, goal-setting, and social support. An increase was observed in daily fruit and vegetable consumption (0.43 servings, 95% CI 0.18, 0.68), vegetables separately (0.35 servings, 95% CI 0.07, 0.63), and legumes (0.04 servings, 95% CI 0.01, 0.08), with smaller increases in fruit (0.03 servings, 95% CI 0.01, 0.05) and meat consumption (-0.03 servings, 95% CI -0.06, -0.01).
Our findings indicate that smartphone apps could play a role in accelerating dietary change, particularly for fruits, vegetables, and legumes, but these changes alone will not make diets more sustainable without meat and dairy reduction. These insights could be used by health practitioners and policymakers when considering apps in their suite of solutions for improving climate and health.