The WHO document on complementary feeding1 suggests that zinc and iron might be “problem nutrients.” The approach used relates the nutrient content of each available food to the energy density and takes into account the maximum quantity of each food a breastfed child is likely to eat. That univariate approach, however, does not explore all possible food combinations. It does not take into account either that other nutritional needs must be covered along with zinc and iron. Finally, the cost of different foods is not discussed, although this may determine which nutrients are deficient in poor communities.In this work, we describe an approach based on cost minimization by linear programming to determine which nutrient may be below recommended intakes in poor families. This method examines the nutrient composition and the cost of available foods in the community and does not have the limitations of other methods. As an...