either becomes insufficient to satisfy the nutritional requirements of older infants and young children. (Throughout this article the term "breast milk" applies also to breast-milk substitutes if breast milk is not available.) Processed supplementary foods are intended primarily for use during normal infants' weaning period and also for the progressive adaptation of infants and young children to ordinary foods. They may be used as part of the total diet or as the only food under unusual circumstances, including emergency conditions.
The scope of these guidelines includes several considerations. Four to six months is the age range selected for introducing cereal-based supplementary foods. It is also recognized that (a) breast milk is adequate to meet the nutritional needs of younger infants under most circumstances, (b) younger infants require a milk product as the major food, and (c) formulated foods that contain a high proportion of milk generally are too expensive for most less privileged population groups [3-6].
The focus is the appropriate use of low-cost, affordable formulated supplementary foods. The emphasis, therefore, is on supplementary foods formulated from vegetable sources. When used as a complement to breast milk, they can provide the dietary increment in energy and nutrients that is needed to meet increasing physiological requirements to support normal growth and development.
An increased demand for low-cost supplementary foods in countries with developing economies is predictable. Current trends in such countries show a dramatic migration of low-income families to urban areas. This is associated with an increased economic necessity for the mothers to participate in work outside the home. Child-minders, often older siblings, are needed to provide food to infants and young children during periods when mothers are unavailable to breast-feed and/or provide supplementary foods. These circumstances necessitate that nutritionally adequate, hygienic foods be available that can be simply and safely prepared and fed, a role that low-cost formulated foods can serve.
Also, in some circumstances it is not possible to provide a nutritionally adequate diet for infants and young children from breast milk or affordable unprocessed local foods. Examples include when the mother dies, when lactation fails, when natural catastrophes decrease available food supplies, and when political upheavals dislocate families. In such emergencies, formulated supplementary foods may provide the only suitable temporary alternative for older infants and young children.
Supplementary or complementary foods are formulated food mixtures meant to be used in addition to breast milk (or breast-milk substitutes) for infants from the age of 46 months until weaned, and thereafter in addition to local foods in order to provide diets that meet nutritional needs.
Processed foods are items that have been modified to achieve special characteristics, such as to improve digestibility, palatability, and ease of preparation.
Age ranges are defined as follows: younger infants, from birth to 4-6 months; older infants, from 4-6 months to 12 months; young children, 1 to 3 years.
PROPOSED MODEL FOR FEEDING OF SUPPLEMENTARY FOODS
Figure 1 shows a conceptual model for timing how foods should be used to complement breast milk so as to meet fully the energy and nutrient needs of infants and young children. Small amounts of the supplementary foods are required initially; their main purpose for older infants is to provide an additional safe source of energy that complements that of breast milk and fully supports growth and development. Beyond the age of 6 months, supplementary foods should gradually be increased in amount and variety to provide not only energy but other essential nutrients, including protein, vitamins, and minerals.
FIG. 1. Conceptual model for the introduction of supplementary foods into the diets of infants and young children (Source: Underwood and Hofvander (4])
The non-nutritional role of supplementary foods in traduced to older infants should also 