Purpose: This study aims to examine how the social capital embedded in health communities influences the knowledge sharing of participating members and drives their organic food consumption. Design/methodology/approach: The structural equation modeling method was used to analyze 228 group members in health knowledge communities established by multi-level marketing firms. Non-response bias was also assessed statistically and appropriate measures taken to minimise the impact of common method variance. Findings: The empirical results showed that: structural capital has no significant relationship with members' knowledge sharing; both the relational and cognitive capital positively affect members' knowledge sharing; members' knowledge collecting behaviour positively affects their purchase intention toward organic foods, but their knowledge donating behaviour has no significant effect; members' purchase intention toward organic foods positively affects their actual purchase behaviour. Practical implications: This paper indicates that higher quality of social capital embedded in that health community would increase more interactive opportunities for participating consumers to understand the organic foods through community activities, and strengthen the organic food value cognition of community members. Hence, companies can make good use of health communities to modify the customers' value propositions, thereby driving their organic food consumptions. Originality/value: Unlike many other empirical studies, this study makes an important contribution to the literature by examining how social capital influences consumers' organic food consumption and their adoption of organic food's values in a detailed manner.