Fasting and postprandial plasma free amino acids of infants and children consuming exclusively potato protein.

Fasting and postprandial plasma free amino acids were studied in nine children on the 9th day of consumption of a diet in which potato protein provided all nitrogen at a marginal level of protein intake (5.03-5.10% protein-calories). The analysis of the potato utilized indicated that 49% of total amino acids (TAA) were free amino acids (AA) and 40% essential amino acids (EAA). Fasting values of TAA and total essential amino acids (TEAA) and the ratios of EAA/TEAA were similar to those obtained previously with milk or casein diets. The low percentage of protein-calories in the diet and relatively poor nitrogen absorption of the potato were reflected in a low (0.236) fasting TEAA/TAA ratio. Met/TEAA and Trp/TEAA ratios were significantly (P less than 0.05) but not markedly lower 3 hours postprandially compared to fasting values, returning to the initial levels 4 hours postprandially. Thr/TEAA ratio was significantly higher (p less than 0.05) at 3 hours but not so at 4 hours. The results suggest that potato protein has an adequate ratio of TEAA/TAA and the balance among individual EAA concentrations should be able to meet the EAA requirements of growing infants and small children if fed and absorbed in sufficient amounts to meet total nitrogen needs.