The roots of concern about food security can be traced back to the Universal Declaration of Human Rights which recognized that everyone has the right to a standard of living adequate for the health and well-being of himself and of his family, including food (United Nations, 1948). Despite technological improvements to increase global food energy per person, regional differences in productivity and distribution problems mean that while some areas have an excess of food, others are lacking (Welch and Graham, 2000). Food secure households should not be at risk of losing access to food, which should be acquired in socially acceptable ways without resorting to emergency food supplies, scavenging, stealing or other coping strategies (FIVIMS, 2003). Purchasing power is therefore essential to guarantee access to sufficient food at the household level (World Bank, 1986; Clover, 2003). Although food security is defined at the level of the individual, it is brought about by a combination of individual, household, community, national and international factors. There is sufficient food at the world level yet distribution and access problems result in millions of people not having enough food (FAO, 2001). The mere presence of food does not entitle a person to consume it. Thus, achieving food security requires four components:
stability of food supply throughout natural, political and/or economic crises;
sufficient availability of food;
sustainable access to affordable food by all; and
effective biological utilization of safe, nutritious food so that every person can lead a healthy and productive life (Pinstrup-Andersen and Pandya-Lorch, 1999).