h glutamic acid intake (the predominant dietary amino acid, especially in vegetable protein) and with each of 4 other amino acids that are relatively higher in vegetable than animal protein (proline, phenylalanine, serine, and cystine). METHODS AND RESULTS: This was a cross-sectional epidemiological study with 4680 persons 40 to 59 years of age from 17 random population samples in China, Japan, the United Kingdom, and the United States. BP was measured 8 times at 4 visits; dietary data (83 nutrients, 18 amino acids) were obtained from 4 standardized, multipass, 24-hour dietary recalls and 2 timed 24-hour urine collections. Dietary glutamic acid (percentage of total protein intake) was inversely related to BP. Across multivariate regression models (model 1, which controlled for age, gender, and sample, through model 5, which controlled for 16 possible nonnutrient and nutrient confounders), estimated average BP differences associated with a glutamic acid intake that was higher by 4.72% of total dietary protein (2 SD) were -1.5 to -3.0 mm Hg systolic and -1.0 to -1.6 mm Hg diastolic (z scores -2.15 to -5.11). Results were similar for the glutamic acid-BP relationship with each of the other amino acids also in the model; eg, with control for 15 variables plus proline, systolic/diastolic pressure differences were -2.7/-2.0 mm Hg (z scores -2.51, -2.82). In these 2-amino acid models, higher intake (by 2 SD) of each of the other amino acids was associated with small BP differences and z scores. CONCLUSIONS: Dietary glutamic acid may have independent BP-lowering effects, which may contribute to the inverse relation of vegetable protein to BP.
This very thorough review paper examines all of the available scientific literature relating to the possible role of monosodium glutamate in provoking allergic reactions and asthma. The review concludes that these studies have failed to demonstrate a clear and consistent link between the ingestion of monosodium glutamate and the development of allergies and asthma. In their conclusions 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