ERYTHROCYTE L-ASPARTYL-L-PHENYLALANINE HYDROLASE ACTIVITY AND PLASMA PHENYLALANINE AND ASPARTATE CONCENTRATIONS IN CHILDREN CONSUMING DIETSHIGH IN ASPARTAME

A deficit of alpha-aspartyl-phenylalanine (alpha-Asp-Phe) hydrolase ac tivity has been suggested as a cause of possible adverse effects of as partame ingestion. Twenty-five normal preschool children and 23 school -age children described by their parents as sensitive to sugar were fe d diets high in sucrose? aspartame, or saccharin for three successive 3-wk periods. Blood samples were obtained at baseline (fasting) and wi thin the last 3 d of each dietary period (postprandial). alpha-Asp-Phe concentrations were below detection limits (0.5 mu mol/L) in all plas ma samples and Phe and Asp concentrations remained within normal limit s. alpha-Asp-Phe hydrolase activities in baseline hemolysate samples d id not differ between groups. One subject had a plasma alpha-Asp-Phe h ydrolase activity > 2 SD below the mean. Despite this low activity, th is subject did not show consistent cognitive or behavioral anomalies t hat could be linked to low hydrolase activity.