Monosodium glutamate (MSG)

The EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion re-evaluating the safety of glutamic acid-glutamates (E 620-625) when used as food additives. Glutamate is absorbed in the intestine and it is presystemically metabolised in the gut wall. No adverse effects were observed in the available short-term, subchronic, chronic, reproductive and developmental studies. The only effect observed was increased kidney weight and increased spleen weight; however, the increase in organ weight was not accompanied by adverse histopathological findings and, therefore, the increase in organ weight was not considered as an adverse effect. The Panel considered that glutamic acid-glutamates (E 620-625) did not raise concern with regards to genotoxicity. From a neurodevelopmental toxicity study, a no observed adverse effect level (NOAEL) of 3,200 mg monosodium glutamate/kg body weight (bw) per day could be identified. The Panel assessed the suitability of human data to be used for the derivation of a health-based guidance value. Although effects on humans were identified human data were not suitable due to the lack of dose-response data from which a dose without effect could be identified. Based on the NOAEL of 3,200 mg monosodium glutamate/kg bw per day from the neurodevelopmental toxicity study and applying the default uncertainty factor of 100, the Panel derived a group acceptable daily intake (ADI) of 30 mg/kg bw per day, expressed as glutamic acid, for glutamic acid and glutamates (E 620-625). The Panel noted that the exposure to glutamic acid and glutamates (E 620-625) exceeded not only the proposed ADI, but also doses associated with adverse effects in humans for some population groups. ※ The abstract text as collected and stored via the API by the pipeline. The key summary is written based solely on this text.

Although monosodium glutamate (MSG) is classified as a causative substance of headache in the International Classification of Headache Disorders 3rd edition (ICHD-III beta), there is no literature in which causal relationship between MSG and headache was comprehensively reviewed. We performed systematic review of human studies which include the incidence of headache after an oral administration of MSG. An analysis was made by separating the human studies with MSG administration with or without food, because of the significant difference of kinetics of glutamate between those conditions (Am J Clin Nutr 37:194-200, 1983; J Nutr 130:1002S-1004S, 2000) and there are some papers which report the difference of the manifestation of symptoms after MSG ingestion with or without food (Food Chem Toxicol 31:1019-1035, 1993; J Nutr 125:2891S-2906S, 1995). Of five papers including six studies with food, none showed a significant difference in the incidence of headache except for the female group in one study. Of five papers including seven studies without food, four studies showed a significant difference. Many of the studies involved administration of MSG in solution at high concentrations (>2 %). Since the distinctive MSG is readily identified at such concentrations, these studies were thought not to be properly blinded. Because of the absence of proper blinding, and the inconsistency of the findings, we conclude that further studies are required to evaluate whether or not a causal relationship exists between MSG ingestion and headache. ※ The abstract text as collected and stored via the API by the pipeline. The key summary is written based solely on this text.

BACKGROUND: Monosodium glutamate (MSG) is the sodium salt of the non-essential amino acid, glutamic acid, and is used as a flavour enhancer. It has been implicated in causing adverse reactions, which have been referred to as "Chinese restaurant syndrome". Over the last two decades there have been a number of studies investigating whether MSG ingestion induces an asthmatic response, and several reviews have been published (ILSI 1991; Stevenson 2000; Woods 2001), but no meta-analysis or Cochrane systematic review has been performed. OBJECTIVES: The objectives of this review are to: 1) identify randomised controlled trials (RCTs) of MSG ingestion and asthma response in adults and children older than two years of age with asthma; 2) assess the methodological quality of these trials; and 3) determine the effect of MSG ingestion on asthma outcomes. SEARCH METHODS: We searched the Cochrane Airways group's Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), and bibliographies of existing trials. Searches were current up to May 2012. SELECTION CRITERIA: We included RCTs that investigated the effect of MSG on chronic asthma in adults and children. DATA COLLECTION AND ANALYSIS: Two authors independently extracted, entered and analysed data from included studies. We contacted study authors for additional information. MAIN RESULTS: Only two cross-over studies involving 24 adults met the eligibility criteria; the challenge dosages of MSG were 1 g, 5 g and 25 mg/kg. They reported the number of subjects who had a maximum fall in forced expiratory volume in the first second (FEV(1)) greater than 15% or 200 mL after MSG or the control challenge. The pooled data found no statistically significant difference between MSG and placebo. One trial reported the mean change at four hours and maximum fall in FEV(1) over four hours after MSG or the placebo challenge, but found no statistically significant difference between interventions. There were no differences in symptom scores, non-specific bronchial hyper-responsiveness (BHR), eosinophil cationic protein (ECP) or tryptase levels in peripheral blood between MSG and control, although we were unable to perform meta-analyses. AUTHORS' CONCLUSIONS: The limited evidence available (n = 24) found no significant difference between MSG or the control challenge for the number of subjects who had a maximum fall in FEV(1) greater than 15% or 200 mL. There is no evidence to support the avoidance of MSG in adults with chronic asthma, but as data were limited, this review cannot provide a reliable evidence base for determining whether MSG avoidance is a worthwhile strategy. We could not find any studies conducted on the effect of MSG in children with chronic asthma. There is therefore, a need for further RCTs to investigate any relationship between MSG and asthma, especially in children. ※ The abstract text as collected and stored via the API by the pipeline. The key summary is written based solely on this text.

Monosodium glutamate (MSG) is an umami substance widely used as flavor enhancer. Although it is generally recognized as being safe by food safety regulatory agencies, several studies have questioned its long-term safety. The purpose of this review was to survey the available literature on preclinical studies and clinical trials regarding the alleged adverse effects of MSG. Here, we aim to provide a comprehensive overview of the reported possible risks that may potentially arise following chronic exposure. Furthermore, we intend to critically evaluate the relevance of this data for dietary human intake. Preclinical studies have associated MSG administration with cardiotoxicity, hepatotoxicity, neurotoxicity, low-grade inflammation, metabolic disarray and premalignant alterations, along with behavioral changes. Moreover, links between MSG consumption and tumorigenesis, increased oxidative stress and apoptosis in thymocytes, as well as genotoxic effects in lymphocytes have been reported. However, in reviewing the available literature, we detected several methodological flaws, which led us to conclude that these studies have limited relevance for extrapolation to dietary human intakes of MSG risk exposure. Clinical trials have focused mainly on the effects of MSG on food intake and energy expenditure. Besides its well-known impact on food palatability, MSG enhances salivary secretion and interferes with carbohydrate metabolism, while the impact on satiety and post-meal recovery of hunger varied in relation to meal composition. Reports on MSG hypersensitivity, also known as 'Chinese restaurant syndrome', or links of its use to increased pain sensitivity and atopic dermatitis were found to have little supporting evidence. Based on the available literature, we conclude that further clinical and epidemiological studies are needed, with an appropriate design, accounting for both added and naturally occurring dietary MSG. Critical analysis of existing literature, establishes that many of the reported negative health effects of MSG have little relevance for chronic human exposure and are poorly informative as they are based on excessive dosing that does not meet with levels normally consumed in food products. ※ The abstract text as collected and stored via the API by the pipeline. The key summary is written based solely on this text.