Monosodium glutamate ‘allergy’: menace or myth?

Abstract

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 prevents 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.

Risk Assessment Paradigm for Glutamate

“…Since the FASEB evaluation [33], a newer double-blind, multi-centre epidemiology study failed to demonstrate any reproducible responses to 5 g of MSG when administered during the course of a meal [35]. Likewise, the review by Williams and Woessner [36] re-iterated previous conclusions that no evidence of symptoms has been associated with the consumption of up to 3 g of MSG per meal. They further state that symptoms have occurred with MSG doses in the 3-5 g (as a single bolus) range, but only in the absence of food on an empty stomach.…”

“…The absence of any adverse effect at such high dietary Table 1. Overview of human studies on MSG considered adequate by the EFSA [2] Reference Study design and result [39] 5,000 mg MSG in a meal: no evidence for symptoms in humans [40] Sensitive subjects (5,000 mg) double blind placebo-controlled double-blind study (0/1,250/2,500/5,000 mg) in citrus beverage: frequency reported symptoms show dose-response and NOAEL at 1,250 mg [35] Multicenter, double-blind, placebo-controlled, multiple-challenge study in 5,000 mg sensitive subjects; dose-response (0/1,250/2,500/5,000 mg citrus flavored beverage) and significant response at all dose levels but not reproducible; no response when 5,000 mg MSG dosed in a meal [36] Review: data till that time: no symptoms up to 3,000 mg and in a meal 3,000 up to 5,000 mg: symptoms observed especially on an empty stomach Risk Assessment Glutamate dose levels of 5% in the diet illustrates the difficulties in defining adequate points of departure for risk assessment for macronutrients from studies in laboratory animals, since this would require even higher dose levels than 5% in the diet which might result in nutritional and metabolic imbalances that would yield secondary adverse effects, including weight loss and increased mortality [1]. The 90-day and 2-year chronic toxicity studies did not indicate potential neurotoxic effects.…”

Padidėjęs Jautrumas Maisto Priedams: Glutamato Klinikiniai Aspektai

“…Pastaraisiais metais atliekama gana daug Glu kaip maisto priedo tyrimų [63,64,65]. Tiriami Glu metabolizmo bei skonio fiziologiniai aspektai, saugumas ir galimas žalin-gas poveikis [28,66,67,68,69,70].…”

“…N. Williamsas ir K. M. Woessneris literatūros apžval-goje "MNG alergija: grėsmė ar mitas?" paneigė, kad MNG yra visų minėtų simptomų ar ligų paūmėjimų priežastis [65].…”

Association between monosodium glutamate intake and sleep-disordered breathing among Chinese adults with normal body weight

“…In 1968, Kwok 15 reported a possible link between MSG and "Chinese restaurant" syndrome including symptoms of numbness, weakness, and heart palpitations [9]. Since then, a range of studies have claimed an association between MSG and health outcomes, including asthma, diabetes, obesity, and allergic rhinitis [10][11][12]. Glutamate is an excitatory neurotransmitter that is intimately involved with sleep-wake states [13], and has been 20 shown to activate a number of brain areas [14], for example the insular cortex, anterior cingulate gyrus, and amygdala [15] which play a crucial role in the central regulation of the autonomic nervous system.…”