food security exists when all people at all times have physical and economic access to sufficient safe and nutritious food to meet their dietary needs and food preferences for an active and healthy life world food summit according to the food and agriculture organization of the united nations fao this definition covers four dimensions of food security physical availability of food economic and physical access to food meeting nutritional requirements and stability of these three aspects over time stamoulis and zezza these four dimensions are directly or indirectly influenced by the level of agricultural productivity