Protein quality evaluation in rats of typical diets for 4- to 6-year-old children from different socioeconomic areas living in Oaxaca, Mexico

Legumes and cereals are principal sources of energy and protein in developing countries. In Oaxaca, Mexico, corn is the primary agricultural crop, therefore corn tortillas and beans are the main energy and protein sources. The objective of this study was to evaluate the protein quality in rats of typical diets for 4- to 6-year-old children from different socioeconomic areas in Oaxaca, Mexico. Composite diets representing the typical diets were formulated and fed to male weanling rats for 10 days. A control diet using casein as the reference diet and one free of nitrogen were included in the study. The apparent protein digestibility was determined in rats using the chromic oxide marker technique and the data was statistically analyzed for differences between control and experimental diets. Rats fed the diet of low income children gained about 2 g/day compared to about 3.8 g/day for the rats fed the control (casein) diet and had the lowest weight gain/g of protein intake. The NPR was 3.52 compared to 4.31 for the control diet. This diet is 67% vegetable protein and 33% animal protein. The diet for the medium income group contained a higher percentage of animal protein, 76% and thus higher digestibility, 78%. The results of this study indicate that the protein quality of children's diets in Oaxaca, Mexico, need to be improved.