Tsai P.-J.PO-CHAO HUANG2020-02-072020-02-0720000022-3166https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034117958&partnerID=40&md5=06c657248e47ad30c0412d00769882c8https://scholars.lib.ntu.edu.tw/handle/123456789/455568This study evaluated the effect of monosodium glutamate (MSG) ingestion as a component of the diet on the 24-h variations in plasma and whole-blood glutamate (GLU) concentrations in healthy adult men. In the first arm of the study, subjects were given test meals without added MSG for 3 d. Protein and energy intakes of the subjects were 1.5 g and 40 kcal/(kg body weight-d), respectively. On d 3, blood samples were collected over the 24-h period. One week later, the same protocol was repeated, except that 100 mg/(kg body weight.d) MSG was added to the meals (15, 40 and 45 mg/kg body weight to breakfast, lunch and dinner, respectively). Both plasma and whole-blood samples were analyzed for free amino acids. Unlike large neutral amino acids, which experienced high peak plasma concentrations at 2100-2300 h, the circadian variations in plasma GLU concentrations were small, varying between 33 and 48 μmol/L on days in which no MSG was fed, and between 32 and 53 μmol/L on days in which MSG was added to the meals. In both trials, plasma GLU concentration increased (P < 0.01) after lunch and dinner, and decreased early in the morning (P < 0.05). Calculated erythrocyte GLU concentrations varied between 500 and 640 μmol/L, with or without MSG addition to the meals. The rather low plasma GLU concentrations over the 24-h period, despite high dietary intake of MSG, indicate that dietary MSG is metabolized very rapidly.Circadian variation; Diet; Erythrocytes; Glutamic acid; Humans; Monosodium glutamate; Plasma[SDGs]SDG3glutamate sodium; glutamic acid; adult; amino acid blood level; caloric intake; circadian rhythm; clinical protocol; conference paper; controlled study; dietary intake; erythrocyte level; human; human cell; human experiment; male; meal; normal human; protein intakeconference paper2-s2.0-0034117958