Conversational interactions contribute not only to the sharing of information and establishment of consensus but also to the formation and maintenance of mutual trust among conversational participants. We introduce a notion of concern alignment to describe the process of mutual trust formation in consensus building dialogues. We propose a conceptual picture of dialogue processes taking place toward concern alignment and trust formation, and provide a qualitative analysis of health guidance dialogues between nurses and patients who were diagnosed as having metabolic syndrome to support the picture. We argue, based on our dialogue analysis result and other research in psychological and anthropological fields, that sharing of knowledge on values and preferences of others negotiated through concern alignment makes it possible for people to choose their actions based on trust on their partners.