Social Determinants of Health: What Research Shows About Addressing Root Causes

Social determinants of health, defined as the conditions in the environments where people are born, live, learn, work, play, and age that affect health outcomes, have become a central concept in public health, healthcare policy, and clinical practice. Research documenting the powerful influence of factors including income, educational attainment, housing stability, food security, neighborhood safety, and social connection on health outcomes has accumulated for decades and now represents one of the most robust bodies of evidence in health science. Translating this evidence into clinical and policy action remains challenging, but the research provides clear guidance about where intervention can have the greatest effect. Income is the social determinant with the most extensive research documentation. Studies tracking individuals over time find robust associations between income and virtually every measurable health outcome: higher income is associated with longer life expectancy, lower rates of chronic disease, better mental health, and lower rates of disability. Research finds that the relationship is graded across the full income distribution rather than simply distinguishing poverty from non-poverty: each step up the income ladder is associated with better health. Research on the mechanisms connecting income to health includes better nutrition and housing, lower chronic stress, greater access to healthcare, and fewer exposures to environmental hazards. Educational attainment has effects on health that appear to be partially independent of income. Research on education and health finds that higher education is associated with better health outcomes even after controlling for income, suggesting that the knowledge, cognitive skills, and social capital that education provides affect health through channels beyond purchasing power. Research on the effects of education policies, including compulsory schooling laws and school quality improvements, on health outcomes in adulthood provides quasi-experimental evidence for causal effects of education on health. Neighborhood effects on health are documented in research that exploits natural experiments to separate the effects of place from the characteristics of people who live in specific neighborhoods. The Moving to Opportunity experiment, which randomly assigned families in high-poverty public housing to receive housing vouchers that allowed them to move to lower-poverty areas, found significant positive effects on health including reduced obesity, lower rates of diabetes, and better mental health for adults who moved, and substantially improved long-term outcomes for children who moved as young children. These findings provide some of the strongest causal evidence that where people live affects health. Food security affects health through both nutritional pathways and through the chronic stress of not knowing whether adequate food will be available. Research on SNAP and food access programs as health interventions finds that food assistance reduces food insecurity with downstream effects on health outcomes including reduced emergency department use and hospitalizations. Studies of community-level food environments, including food desert and food swamp research, find associations between limited healthy food access and worse diet quality and chronic disease outcomes. Healthcare systems are increasingly attempting to screen patients for social determinants and connect them with community resources that address identified needs. Research on social determinants screening in clinical settings finds that patients are generally receptive to being asked about social needs, and that a significant proportion of patients report unmet social needs including housing instability, food insecurity, and transportation barriers. The more difficult question is what healthcare systems can do when social needs are identified: connecting patients to resources requires community resources to exist, and research on referral effectiveness finds that unmet community resource capacity limits the benefit of clinical screening. Accountable Health Communities, a CMS demonstration program that provided funding to screen for and address social determinants of health in Medicare and Medicaid populations, has been evaluated and found to produce modest improvements in health outcomes and healthcare utilization for some subgroups. The evidence that clinical social determinants programs can reduce healthcare costs sufficiently to finance themselves is mixed, with some analyses finding positive returns and others finding that the cost savings do not fully offset program costs. Whether the social value of improved health and wellbeing justifies these investments even when they do not produce healthcare cost savings is ultimately a values question. Policy interventions that address social determinants systemically, through changes in housing policy, income support, education funding, and environmental regulation, have larger potential effects on population health than clinical screening and referral programs. Research on the health effects of policy changes that affect social determinants, including Medicaid expansion, housing voucher programs, and minimum wage increases, provides evidence that these policies improve health outcomes and may reduce health disparities. Building the evidence base for social policy as health policy is an important contribution of social determinants research to the policy conversation about how to improve population health most effectively.