Digital peer support interventions have the potential to promote healthy lifestyles and better mental health. This systematic review and meta-analysis synthesizes evidence on the effectiveness of digital peer support interventions for enhancing physical and mental health in healthy individuals rather than those diagnosed with a clinical condition.

First, we evaluated the impact of digital peer support interventions on physical and mental health outcomes by attending to sources of peer support (informal, naturally occurring peer support; formal support from trained peers), effectiveness demonstrated through different study designs (pre–post comparison vs. well-controlled experimental conditions) and long-term effects of interventions. Second, we examined whether features of digital peer support interventions – specifically, dosage, uptake and platform affordances – moderated intervention effectiveness. Third, we considered moderating effects of individual differences (age and existing health conditions) and country.

Using random-effects modelling, which included 47 studies with 76 effect sizes on physical health, and 73 studies with 118 effect sizes on mental health, we found a moderate effect of digital peer support in improving physical health (standardized mean difference (SMD) = 0.35, p < 0.001; 95% CI: 0.30–0.41) and a large effect in enhancing mental health (standardized mean difference(SMD) = 0.53, p < 0.001; 95% CI: 0.46–0.61), which were similar across ages and individuals with varying degree of existing health conditions. Different sources of peer support demonstrated similar effects on physical health, but informal, naturally occurring peer support was more effective in bolstering mental health than formal support from trained peers, producing large effects that were comparable to online professional support. Positive effects on physical health were sustained over follow-up assessments, but weakened for mental health over time. Greater dosages of intervention had decreased effectiveness, but uptake of intervention did not moderate the effects on health. Interventions delivered on platforms that afford greater interactivity (apps, social networking sites and video conferencing) were more effective than those with lower interactivity (forums, websites and emails). Digital peer support interventions had stronger effects on improving physical health in Western countries than Eastern countries, but stronger effects on improving mental health in Eastern than Western countries.

Our findings contribute to the nascent conceptual models of digital peer support, lend credence to digital peer support as a scalable preventive intervention with real-world benefits in bolstering individuals’ physical and mental health and provide important insights into best practices.