This study investigates the perceptions of medicinal and medicated food (MMF) use of Taiwanese immigrant families in the US. The background of use of food as medicine and for health promotion in Chinese history and in Taiwan and the situation of immigrants with transnational ties suggested that the Family Food Decision Making (FFDM) framework could be fruitfully applied along with the life course perspective (LCP) and expanded by the study. Informed by initial informant engagement, a preliminary framework informed design of the survey, including a questionnaire answered by 113 participants. The results were analyzed using descriptive statistics. Together with informant engagement of survey participants, it revealed a need to build trust relationships and social connections in interviewing. A constructivist grounded theory (CGT) approach to in-depth interviews was applied, with modifications for CGT analysis incorporating language translation. Twelve interviews were conducted. The building of trust and a pattern of interviewee behavior resulted in a distinctively egalitarian interview style. The study's findings show that Taiwanese immigrants perceive the meaning of MMF in terms of taste and medicinal effectiveness and can practice amateur or connoisseur MMF usages. Parents are a major influence on transmission of MMF use; personality, religious food practices, and degrees of connection with Taiwanese Chinese medicine use also affect FFDM. Childhood training to accept MMF taste can further continuance of MMF use in later life. Recently increased transnational contacts contribute to bi-directional Taiwan/US influences on MMF sourcing and knowledge transmission. This has affected synergistically changing MMF environments in both places. These and other insights contribute to theorization about interactions of MMF meaning, family FDM dynamics, and human environmental influences, e.g., food traditions and systems and social relations. An MMF-expanded framework is developed from the FFDM Ecological System Framework. Methodological insights on building trust relationships and egalitarian influences on the interviewing mode inspired development of a dyadic dialogue method (DDM) that could aid FFDM Collaborative Engaged Research. The study also suggests three directions for future FFDM and MMF research: incorporating concern with FFDM efficacy, familycommunity MMF use collaborative engaged research, and exploration of Taiwan and US MMF systems.