Plasma glutamate concentrations in 1-year-old infants and adults ingesting monosodium L-glutamate in consommé

This study tested the hypothesis that infants metabolize glutamate more slowly than adults. Eight 1-yr-old infants ingested 160 ml of a beef consommé providing monosodium L-glutamate at 0, 25, and 50 mg/kg body weight. Plasma glutamate and aspartate concentrations were measured sequentially for the next 2 h. The results were compared to values noted in nine adult subjects ingesting equivalent doses of monosodium L-glutamate in consommé. In adults, mean (+/- SD) peak plasma glutamate concentrations were 5.59 +/- 1.56, 10.2 +/- 2.08, and 17.0 +/- 8.06 mumol/dl, respectively; the area under the plasma glutamate concentration time curves were 96 +/- 42, 257 +/- 80, and 442 +/- 303 mumol/dl X min, respectively. In infants, the mean (+/- SD) peak plasma glutamate concentrations were 6.94 +/- 1.43, 10.6 +/- 2.36, and 12.0 +/- 1.16 mumol/dl, respectively; the plasma glutamate area under the curve values were 47 +/- 28, 191 +/- 85, and 358 +/- 105 mumol/dl X min, respectively. The data indicate that the plasma glutamate concentration response in 1-yr-old infants ingesting MSG at these glutamate doses is no higher than values observed in adult subjects.