Like most other low and middle-income countries, South Africa must address a rising burden of diet-related chronic disease in a situation of persistent food insecurity and undernutrition. Supply-side policy interventions are a critical component of action to address the double burden of malnutrition. However, the food supply is governed by a number of different policy sectors, and policy incoherence can occur between government action to promote a healthy food supply and objectives for economic liberalization. We analysed the coherence of food supply policy content with respect to nutrition and food security in South Africa, and conducted 14 in-depth interviews with 22 public and private sector actors to identify opportunities to improve policy coherence across sectors governing the food supply. Drawing on Sabatier's conceptualization of actors as influential in shaping policy outcomes, we identified three coalitions of actors related to food security and nutrition in South Africa: the dominant Economic Growth coalition, the Food Security coalition, and the Health coalition. Understanding the frames, beliefs and resources held by these coalitions offers insights into the policy tensions faced by the Government of South Africa with respect to the food supply. The analysis indicates that the current reconsideration of economic policy agendas favouring liberalization in South Africa, including the termination of most bilateral investment treaties, may present an opportunity for increased recognition of food security and nutrition priorities in food supply policy making. Opportunities to strengthen policy coherence across the food supply for food security and nutrition include: specific changes to economic policy relating to the food supply that achieve both food security/nutrition and economic objectives; creating links between producers and consumers, through markets and fiscal incentives that make healthy / fresh foods more accessible and affordable; increasing formal avenues for engagement by Civil Society in nutrition and food security policy making; and including consideration of the nutritional quality of the food supply in policy objectives across sectors, to create a framework for policy coherence across sectors relating to the food supply.