Utilization of the protein and energy of the white potato by human infants

The digestibility and protein quality of the white potato were studied in 11 infants, ages 8-35 months, recovering from malnutrition. Seven 9-day dietary periods comprised the study. Digestibility was assessed by metabolic balance during the last 6 days of dietary periods in which potato provided 25%, 50% or 75% of dietary energy. Casein-based control dietary periods preceded and/or followed each potato dietary period. Fecal wet and dry weights, fecal energy, computed fecal carbohydrate and fecal fat during consumption of the 25% potato diet did not differ from control. Analysis of variance showed that consumption of increasing amounts of potatoes produced a significant linear increase in all parameters of digestibility except fecal fat. Fecal wet weight and energy content during the 75% potato period were more than double control values. Regression analysis of data from potato dietary periods showed fecal wet weight to be an excellent predictor of fecal dry weight (r = 0.904), energy content (r = 0.785) and computed fecal carbohydrate (r = 0.770). Protein quality of potato was assessed with N balance studies during the dietary periods in which potato provided all dietary protein (approximately 5% protein kcal). Apparent N retention was 78% of that from an isonitrogenous casein control diet. Decreased apparent N absorption was primarily responsible for the difference; the "biologic value" (percent of absorbed N that was retained) was similar for both diets.