Plasma amino acid patterns and visceral protein status in users and nonusers of monosodium glutamate

Free amino acids in plasma and total protein, albumin, transferrin and retinol-binding protein (RBP) in serum were determined in two groups of healthy adults consisting of 10 female nonusers and 10 female users of monosodium glutamate (MSG). Users or nonusers of MSG were those consuming or not consuming MSG regularly at their homes for at least 1 y. On the bases of body mass index and serum protein concentrations, each of the two groups appeared to have an adequate protein-energy status. Fasting plasma glutamate concentrations in female nonusers and users of MSG were 22.4 +/- 3.2 and 21.8 +/- 2.0 nmol/mL (means +/- SEM), respectively; these values were not significantly different. These findings indicate that there is no glutamate accumulation in the plasma of MSG users and imply the safety of long-term MSG intake.