ons the authors state “In short, the current evidence does not suggest that MSG is a significant contributor to asthma, urticaria, angio-oedema or rhinitis”.
Monosodium glutamate ‘allergy’: menace or myth?
A.N. Williams and K. M. Woessner
Clinical & Experimental Allergy, 39, 640-646
Monosodium glutamate (MSG) is a salt form of a non-essential amino acid commonly used as a food additive for its unique flavour enhancing qualities. Since the first description of the ‘monosodium glutamate symptom complex’, originally described in 1968 as the ‘Chinese restaurant syndrome’, a number of anecdotal reports and small clinical studies of variable quality have attributed a variety of symptoms to the dietary ingestion of MSG. Descriptions of MSG-induced asthma, urticaria, angio-oedema, and rhinitis have prompted some to suggest that MSG should be an aetiologic consideration in patients presenting with these conditions. This review presents a critical review of the available literature related to the possible role of MSG in the so-called ‘Chinese restaurant syndrome’ and in eliciting asthmatic bronchospasm, urticaria, angio-oedema, and rhinitis. Despite concerns raised by early reports, decades of research have failed to demonstrate a clear and consistent relationship between MSG ingestion and the development of these conditions.
Glutamate is the most abundant amino acid in protein. We take in about 20 grams of glutamate per day in our normal diet. Since monosodium glutamate has been used widely as a seasoning, some papers have appeared which have questioned the safety of glutamate. In 1987, the Joint Expert Committee on Food Additives (JECFA) of the United Nations Food and Agriculture Organization (FAO) and the World Health Organization (WHO) carefully reviewed more than 200 scientific reports and evaluated glutamate as “Acceptable Daily Intake (ADI) not specified.” This meant that the Committee concluded that no upper intake limit was necessary, placing monosodium glutamate in the category of the safest of all food additives.
Supplement The Safety Evaluation of Monosodium Glutamate
Ronald Walker and John R. Lupien*
Journal of Nutrition. 2000;130:1049S-1052S. School of Biological Sciences, University of Surrey, Guildford GU2 5XH, Surrey, UK and *Food and Nutrition Division, FAO, 00100 Roma, Italy
L-Glutamic acid and its ammonium, calcium, monosodium and potassium salts were evaluated by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 1988. The Committee noted that intestinal and hepatic metabolism results in elevation of levels in systemic circulation only after extremely high doses given by gavage (>30mg/kg body weight). Ingestion of monosodium glutamate (MSG) was not associated with elevated levels in maternal milk, and glutamate did not readily pass the placental barrier. Human infants metabolized glutamate similarly to adults. Conventional toxicity studies using dietary administration of MSG in several species did not reveal any specific toxic or carcinogenic effects nor were there any adverse outcomes in reproduction and teratology studies. Attention was paid to central nervous system lesions produced in several species after parenteral administration of MSG or as a consequence of very high doses by gavage. Comparative studies indicated that the neonatal mouse was most sensitive to neuronal injury; older animals and other species (including primates) were less so. Blood levels of glutamate associated with lesions of the hypothalamus in the neonatal mouse were not approached in humans even after bolus doses of 10 g MSG in drinking water. Because human studies failed to confirm an involvement of MSG in “Chinese Restaurant Syndrome” or other idiosyncratic intolerance, the JECFA allocated an “acceptable daily intake (ADI) not specified” to glutamic acid and its salts. No additional risk to infants was indicated. The Scientific Committee for Food (SCF) of the European Commission reached a similar evaluation in 1991. The conclusions of a subsequent review by the Federation of American Societies for Experimental Biology