In this doctoral dissertation, I adress the issue of changes in foodways, using a socio-cultural framework, as this approach takes as a starting point the dynamic co-construction between the person and her or his environment. Within this framework, I place particular emphasis on approaches underlining the importance of dialogicity and socio-materiality in human activities. I select several conceptual tools that I consider as useful to analyze these processes of navigation of the world, namely positioning, rupture/transition, responsibility and creativity. The phenomenon that I examine with this theoretical framework is the elaboration of a foodway at an individual level and, more specifically, the questioning and refusal of products of animal origin, which, depending notably on the extent of the avoidance, might be labelled vegetarianism or veganism. I argue that this phenomenon is of high interest notably because it is at the core of societal debates and challenges related to animal ethics, environmental impact and health issues. In this thesis, I conceptualize changes in foodways as movements of repositioning in a foodscape (a landscape of discourses and practices related to food and eating) and I address the following research question: What are the positioning dynamics around the consumption of products of animal origin among people who changed their foodway regarding these products? In order to address this question, I use a qualitative approach allowing me to understand each situation and trajectory in its complexity and dynamicity. I propose a methodological design combining a narrative interview, a dialogical experiment, and a filmed observation. As a complement, I also collect elements from the socio-cultural environment such as newspaper articles. Participants are ten adults who changed their food habits in relation to products of animal origin.