Economic research on global food supplies has been always diverse and multidimensional. The role and potential of the food producing sectors, and the basic problems caused by the supply constraints, were issues which dominated research in the early parts of this century. This approach looked at the technological and economic capabilities of the agricultural sector, the rate of growth of the total and per capita agricultural output, and the changing structure and geographical patterns of agricultural and especially of food production. Research work, dealing with the growing population and the increasing food needs has been developing and, in fact, oscillating between two extremes in the past decades: one which approached the issues from the perspectives of the changing effective demand for food; and the other from the aspects of the changing physical needs of the people. The first approach defined potential demand as a function of population and income growth. Researchers, looking at the future volume and patterns of the effective demand for food, devoted great attention to the changes of per capita income level, its impact on the share of food in the total consumer expenditure, and its changing composition towards a better and more balanced diet. The entitlement approach could be, in fact, in certain ways also related to the 'effective demand' concept, as a deliberate policy to reduce famine through increasing the income for the poor. The other extreme looked at the food supply issues basically from the perspective of the basic nutrition requirements of individuals in the given country, and combined it with the expected increase of population. It has become increasingly understood that, in public policies aiming at the achievement of sustainable food security, a complex and multi-dimensional approach is needed.