Food insecurity is a compelling global problem with compound causation in population expansion, industrialization of agriculture and food marketing, and environmental deterioration. The United Nations system has addressed the need for food and nutrition security from a foundation of human rights law and expressed the requirement for all people to be food secure with sustainable food systems and diets. Food biodiversity is a component of the sustainable food systems that are practiced by Indigenous Peoples living in intact ecosystems. This paper describes the evolution of the principles of food and nutrition security within the United Nations, explores current issues, and highlights a program with Indigenous Peoples' food systems that includes health promotion interventions using biodiverse local foods. Highlighted are the roles of ethnobiologists in understanding the principles and concepts underlying food and nutrition security, in promoting food biodiversity and healthy food systems, and in contributing to policies protecting food biodiversity and food and nutrition security.