Social capital and health: A systematic review of systematic reviews

There are many systematic reviews on social capital (SC) and various health outcomes, but each of these reviews shows one piece of the larger SC and health puzzle. The aim of this research was to systematically review systematic reviews on SC and health, in order to provide an overview of existing evidence and to identify strategies for future research. Nine databases were searched for key words that could fall under the broad umbrella of SC and health outcomes. We screened 4941 titles and abstracts and read 187 reviews before retaining 20 of them. A critical appraisal of each review was conducted. The reviews show there is good evidence to suggest that SC predicts better mental and physical health, and indicators of SC are protective against mortality. At the same time, many reviews also found numerous non-significant and negative relationships that are important to consider. It was unclear whether SC interventions for health were really improving SC, or other aspects of the social environment. Overall, this research shows that evidence on how various aspects of SC affect different health outcomes for different actors remains unclear. Intergroup and lifecourse perspectives could help clarify this link. Future research could benefit from conceptualizing the link between SC and health in a what, who, where, when, why and how framework.