Quality protein maize: digestibility and utilization by recovering malnourished infants

The opaque-2 gene was shown years ago to increase the nitrogen, lysine, and tryptophan contents of maize and to markedly increase its nutritional value for small children. Concerns about decreased yield, resistance, and acceptability discouraged further development of the gene. Quality protein maize, while retaining the opaque-2 characteristics, has overcome those constraints. Six recovering malnourished infants received diets in which all of the 6.4% protein energy was supplied by casein, quality protein maize, or common maize. The quality protein maize supplied 60% and common maize 75% of total energy. Vegetable oil was added to increase fat contents to 10% of total energy in all diets. Energy digestibility was less (87% and 84%) from quality protein maize and common maize than from casein diets (94%); most of the difference was due to carbohydrate digestibility. Apparent N absorptions from quality protein maize (70 +/- 5%) and common maize (69% +/- 7%) were much lower (P less than .01) than from casein (82% +/- 4%). Apparent retention of N from quality protein maize (34 +/- 4%) was less (P less than .01) than from casein (41% +/- 9%) but greater (P less than .01) than from common maize (22% +/- 10%). Breath hydrogen excretions were usually greater during quality protein maize consumption than during casein diets but not nearly as much as those during common maize diets. The nutritional advantages of quality protein maize v common maize are of a magnitude that must be exploited for the advantage of children in maize-consuming poor countries.