Abstract : Diet is a major determinant of health and an essential lever for preventing non communicable diseases. However, it cannot be understood independently from the food systems that shape food supply, prices, accessibility, and attractiveness, and that simultaneously contribute to environmental pressures. Recent research highlights a growing convergence between public health objectives and ecological sustainability, prompting an expanded analysis of the role of food environments in structuring individual choices. In this context, nutritional guidelines are evolving and now promote a predominantly plant based, minimally processed diet that is compatible with sustainable production methods. Nevertheless, the social sciences remind us that eating practices remain shaped by cultural, economic, and social determinants, and that inequalities in access to healthy and sustainable food persist. For medical practice, these perspectives call for embedding nutritional support within the material and cultural realities of patients and for recognizing food environments as full fledged determinants of health. Understanding these interdependencies strengthens the coherence, effectiveness, and equity of nutritional prevention strategies.