An adequate supply of energy, micronutrients and macronutrients is essential to achieve food and nutrition security to prevent malnutrition. Socio-economic, political, and climatic events, however, can affect the supply of food and nutrients. We assessed country-level supply trends of food and nutrients and their sources within the context of policy changes and political, socio-economic and climatic events from 1961 to 2013 in Zambia. Due to the lack of national food consumption data, food supply data from the FAO food balance sheets, matched to food composition tables, were used to estimate the energy, macronutrient and micronutrient content of 264 food items available to Zambia. We calculated historical nutrient supplies based on demographic characteristics and population-level dietary requirements. Results showed that Zambia was nutrition insecure from 1961 to 2013 for key micronutrients vitamin A, folate, riboflavin, vitamin B12, calcium, zinc, iron, and energy-deficient from the late-1980s. The diet has not substantially changed over time, with maize being the dominant food source. However, refined energy-dense food has steadily increased in the diet coupled with a reduction in fibre. These nutrient supply and dietary pattern trends coincide with specific socio-economic, policy, political, and climatic events from the 1970s to the early-mid 2000s, such as population growth, maize subsidy and crop diversification policies, regime change and drought. This study shows how policy, political and climatic events have been central features shaping nutrient supplies and the consequences for nutrition security. The study provides a context to inform future food policies to improve food and nutrition security.