Re-evaluation of glutamic acid (E 620), sodium glutamate (E 621), potassium glutamate (E 622), calcium glutamate (E 623), ammonium glutamate (E 624) and magnesium glutamate (E 625) as food additives

Isolation and Identification of Novel Taste-Modulating N2-Guanosine 5'-Monophosphate Derivatives Generated by Maillard-Type Reactions

Several compounds with taste-modulating properties have been investigated, improving the taste impression without having a pronounced intrinsic taste. The best-known representatives of umami taste-modulating compounds are ribonucleotides and their derivatives. Especially the thio derivatives showed high taste-modulating potential in structure-activity relationship investigations. Therefore, this study focuses on the formation of guanosine 5'-monophosphate derivatives consisting of Maillard-type generated compounds like the aroma-active thiols (2-methyl-3-furanthiol, 3-mercapto-2-pentanone, 2-furfurylthiol) and formaldehyde to gain insights into the potential of combinations of taste and aroma-active compounds. One literature-known (N2-(furfurylthiomethyl)-guanosine 5'-monophosphate) and three new derivatives (N2-(2-methyl-1-furylthiomethyl)-guanosine 5'-monophosphate, N2-((5-hydroxymethyl)-2-methyl-1-furylthiomethyl)-guanosine 5'-monophosphate, N2-((2-pentanon-1-yl)thiomethyl)-guanosine 5'-monophosphate) were successfully produced using green natural deep eutectic solvents and isolated, and their structures were completely elucidated. Besides the intrinsic taste properties, the kokumi and umami taste-modulating effects of the four derivatives were evaluated via psychophysical investigations, ranging from 19 to 22 μmol/L.

Central amygdala is related to the reduction of aggressive behavior by monosodium glutamate ingestion during the period of development in an ADHD model rat

Introduction

Monosodium glutamate (MSG), an umami substance, stimulates the gut-brain axis communication via gut umami receptors and the subsequent vagus nerves. However, the brain mechanism underlying the effect of MSG ingestion during the developmental period on aggression has not yet been clarified. We first tried to establish new experimental conditions to be more appropriate for detailed analysis of the brain, and then investigated the effects of MSG ingestion on aggressive behavior during the developmental stage of an ADHD rat model.

Methods

Long-Evans, WKY/Izm, SHR/Izm, and SHR-SP/Ezo were individually housed from postnatal day 25 for 5 weeks. Post-weaning social isolation (PWSI) was given to escalate aggressive behavior. The resident-intruder test, that is conducted during the subjective night, was used for a detailed analysis of aggression, including the frequency, duration, and latency of anogenital sniffing, aggressive grooming, and attack behavior. Immunohistochemistry of c-Fos expression was conducted in all strains to predict potential aggression-related brain areas. Finally, the most aggressive strain, SHR/Izm, a known model of attention-deficit hyperactivity disorder (ADHD), was used to investigate the effect of MSG ingestion (60 mM solution) on aggression, followed by c-Fos immunostaining in aggression-related areas. Bilateral subdiaphragmatic vagotomy was performed to verify the importance of gut-brain interactions in the effect of MSG.

Results

The resident intruder test revealed that SHR/Izm rats were the most aggressive among the four strains for all aggression parameters tested. SHR/Izm rats also showed the highest number of c-Fos + cells in aggression-related brain areas, including the central amygdala (CeA). MSG ingestion significantly decreased the frequency and duration of aggressive grooming and attack behavior and increased the latency of attack behavior. Furthermore, MSG administration successfully increased c-Fos positive cell number in the intermediate nucleus of the solitary tract (iNTS), a terminal of the gastrointestinal sensory afferent fiber of the vagus nerve, and modulated c-Fos positive cells in the CeA. Interestingly, vagotomy diminished the MSG effects on aggression and c-Fos expression in the iNTS and CeA.

Conclusion

MSG ingestion decreased PWSI-induced aggression in SHR/Izm, which was mediated by the vagus nerve related to the stimulation of iNTS and modulation of CeA activity.

Disruptive consequences of monosodium glutamate on male reproductive function: A review

Monosodium glutamate (MSG) is one of the most extensively used flavour enhancers worldwide. Although it is widely regarded as a safe food additive with no recommended daily dosage, its over-consumption has been associated with notably pathophysiological events in various tissues and organs of the body. Previous studies have reported of the neuro- cardio- and hepato- toxic effects of its excessive exposure. Moreover, the food additive instigates metabolic dysfunction. It has been established that MSG damages male reproductive accessory organs like prostate glands and epididymis. In addition, it impairs serum enzymatic activities and serum levels of testosterone, gonadotropin-releasing hormone, luteinizing hormone and cholesterol. Reduced sperm count, sperm motility, sperm morphology, and sperm viability, imbalances in male reproductive hormones, alongside alteration in the histoarchitecture of the testes and other male reproductive tissues have also been connected with excessive exposure to MSG. Literature reports affirm the link between the over-consumption of MSG and reproductive organ weight and male sexual behaviour. This review article addresses the multi-systemic effects of exposure to MSG and the possible mechanism of action of the compound with a focus on the negative implications of the food additive on male reproductive functions and the possible role of natural antioxidants in male reproductive functions. carefully selected keywords were used during the literature search to gather credible and up-to-date information about the subject matter.

Potential Defence Mechanisms Triggered by Monosodium Glutamate Sub-Chronic Consumption in Two-Year-Old Wistar Rats

Monosodium glutamate (MSG) is the sodium salt of glutamic acid (GLA), used as a flavour enhancer. MSG is considered a controversial substance. It is incriminated in disturbing the antioxidant system, but also has beneficial effects, as GLA metabolism plays a crucial role in homeostasis. This study highlights which positive or negative aspects of MSG sub-chronic consumption are better reflected in subjects potentially affected by advanced age. Daily doses of MSG were administered to four groups of two-year-old Wistar rats for 90 days: (I) 185 mg/kg bw, (II) 1500 mg/kg bw, (III) 3000 mg/kg bw and (IV) 6000 mg/kg bw, compared to a MSG non-consumer group. Aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, direct and total bilirubin, total cholesterol, triglycerides, creatinine and urea levels were analysed; stomach, liver and kidney samples were subjected to histopathological analysis. Although, in most cases, there were no statistical differences, interesting aspects of the dose-effect relationship were observed. After MSG sub-chronic consumption, the positive aspects of GLA seem to be reflected better than the negative ones. The hormesis effect, with low-level reactive oxygen species' protective effects and GLA metabolism, may represent the hypothesis of a potential defence mechanism triggered by MSG sub-chronic consumption in ageing rats.

Production of GABA in milk fermented by Bifidobacterium adolescentis strains selected on the bases of their technological and gastrointestinal performance

There is an increasing interest in producing foods enriched in gamma-aminobutyric acid (GABA), due to their purported health promoting attributes. GABA is the main inhibitor neurotransmitter of the central nervous system, and several microbial species are capable to produce it through decarboxylation of glutamate. Among them, several lactic acid bacteria species have been previously investigated as an appealing alternative to produce GABA enriched foods via microbial fermentation. In this work we report for the first time an investigation into the possibility of utilizing high GABA-producing Bifidobacterium adolescentis strains as a mean to produce fermented probiotic milks naturally enriched in GABA. To this end, in silico and in vitro analyses were conducted in a collection of GABA-producing B. adolescentis strains, with the main goal to scrutinize their metabolic and safety traits, including antibiotic resistance patterns, as well as their technological robustness and performance to survive a simulated gastrointestinal passage. One of the strains, IPLA60004, exhibited better survival to lyophilization and cold storage (for up to 4 weeks at 4 °C), as well as survival to gastrointestinal passage, as compared to the other strains under investigation. Besides, the elaboration of milk drinks fermented with this strain, yielded products with the highest GABA concentration and viable bifidobacterial cell counts, achieving conversion rates of the precursor, monosodium glutamate (GMS), up to 70 %. To our knowledge, this is the first report on the elaboration of GABA enriched milks through fermentation with B. adolescentis.

Dietary Exposure to Glutamates of 2- to 5-Year-Old Toddlers in China Using the Duplicate Diet Method

A duplicate diet collection method was used to estimate dietary exposure to glutamates in children aged 2-5 years in selected provinces of China. Daily duplicate diet samples were collected from 86 healthy toddlers over three consecutive days. Glutamates were analyzed using ultra-high-pressure liquid chromatography-MS/MS (UHPLC-MS/MS). Results showed that the highest glutamates content was found in mixed meals, at 5.12 mg/kg, followed by powdered formula (3.89 mg/kg), and milk and dairy products (2.29 mg/kg). The total mean daily dietary exposure for subjects was 0.20 mg/kg BW, and P95 daily dietary exposure was 0.44 mg/kg BW, both below the acceptable daily intake (ADI) (120 mg/kg BW) recommended by the Joint (FAO/WHO) Expert Committee on Food Additives (JECFA) and the ADI (30 mg/kg BW) set by the European Food Safety Authority (EFSA). Hence it can be considered that glutamates exposure would cause low risk in this group.

Phosphorylation of Alkali Extracted Mandua Starch by STPP/STMP for Improving Digestion Resistibility

The chemical modifications of starch granules have been adopted to improve the characteristics, viz., paste clarity, resistant starch content, thermal stability, and so forth. The modified starch has been applied as a biopolymer in developing various preparations of food, nutraceutical, and pharmaceutical importance. The present work is focused on phosphorylation of alkali extracted mandua starch for improving digestion resistibility. The phosphorylation of mandua starch extracted from grains of Eleusine coracana (family Poaceae) was carried out by sodium tripolyphosphate/sodium trimetaphosphate at alkaline pH. After chemical treatment of mandua starch, the resistant starch (RS) content was increased significantly. The digestibility of chemically modified starch (CMS) was decreased down after treating by the phosphorylation process. The digestibility of CMS and alkali extracted mandua starch (AMS) in simulated intestinal fluid was found to be 32.64 ± 1.98% w/w and 61.12 ± 2.54% w/w, respectively. After chemical modification of mandua starch, a decrement was observed in amylose content, water-binding capacity, and swelling power. In the three-stage decomposition pattern of CMS studied by thermal gravimetric analysis, the significant changes in decomposition behavior also affirmed the impact of cross-linking in the improvement of stability of internal structure and resistibility of starch. In Fourier transform infrared (FTIR), the formation of the P=O bond was observed in CMS at 1250 cm^-1. The acute and sub-acute toxicity studies in terms of behavioral, haematological, and enzymological parameters for CMS were not different significantly from AMS and control (p > 0.05). The cellular architecture of the liver and the kidney were found normal after consumption of CMS. The results revealed that significant increment in RS fraction occurred after cross-linking of mandua starch. The prepared starch may be applied in developing various formulations of food and pharmaceutical importance.

Discovering Novel Bioactivities of Controversial Food Additives by Means of Simple Zebrafish Embryotoxicity (ZET) Assays

The rising concerns about controversial food additives' potential hazardous properties require extensive yet animal-minimized testing strategies. Zebrafish embryos are the ideal in vivo model representing both human and environmental health. In this study, we exposed zebrafish embryos to eight controversial food additives. Our results indicate that Sodium Benzoate is a Cat.3 aquatic toxicant, while Quinoline Yellow is a strong teratogen. At high concentrations, non-toxic chemicals induced similar phenotypes, suggesting the impact of ionic strength and the applicability of the darkened yolk phenotype as an indicator of nephrotoxicity. Three food additives showed unpredicted bioactivities on the zebrafish embryos: Brilliant Blue could weaken the embryonic yolk, Quinoline Yellow may interfere with nutrient metabolism, and Azorubine induced precocious zebrafish hatching. In conclusion, the zebrafish embryo is ideal for high throughput chemical safety and toxicity screening, allowing systematic detection of biological effects-especially those unexpected by targeted in vitro and in silico models. Additionally, our data suggest the need to reconsider the safety status of food additives Quinoline Yellow, Brilliant Blue, Sodium Benzoate, and other controversial food additives in further studies, as well as pave the way to further applications based on the newly found properties of Brilliant Blue and Azorubine.

Hypersensitivity Reactions to Food Additives-Preservatives, Antioxidants, Flavor Enhancers

There have been reports of food hypersensitivity reactions to food additives (HFA) for many years. The mechanisms of HFA and their frequency are difficult to precisely define, as most of the data come from outdated studies with poor methodology. In 2020, the European Food Safety Authority completed a review of additives, examining their influence on the occurrence of HFA, but did not include all of them. The aim of this review is to systematise knowledge about selected groups of food additives (FAs) and the HFA induced by them. We also briefly discuss the issues of diagnosis and therapy in this disease. FAs are commonly used in prosscessed foods, but HFA appears to be a rare phenomenon. Identification of the FA responsible for hypersensitivity and its treatment is difficult. Diagnosis is a challenge for the clinician and for the patient. A food diary is a helpful diagnostic tool. It allows diet therapy to be monitored based on the partial or complete elimination of products containing a harmful additive. An elimination diet must not be deficient, and symptomatic pharmacotherapy may be necessary if its application is ineffective. Taking all this into account, we conclude that it is necessary to conduct randomised multicentre studies based on the double-blind placebo control protocol in this field.

Is L-Glutamate Toxic to Neurons and Thereby Contributes to Neuronal Loss and Neurodegeneration? A Systematic Review

L-glutamate (L-Glu) is a nonessential amino acid, but an extensively utilised excitatory neurotransmitter with critical roles in normal brain function. Aberrant accumulation of L-Glu has been linked to neurotoxicity and neurodegeneration. To investigate this further, we systematically reviewed the literature to evaluate the effects of L-Glu on neuronal viability linked to the pathogenesis and/or progression of neurodegenerative diseases (NDDs). A search in PubMed, Medline, Embase, and Web of Science Core Collection was conducted to retrieve studies that investigated an association between L-Glu and pathology for five NDDs: Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Huntington’s disease (HD). Together, 4060 studies were identified, of which 71 met eligibility criteria. Despite several inadequacies, including small sample size, employment of supraphysiological concentrations, and a range of administration routes, it was concluded that exposure to L-Glu in vitro or in vivo has multiple pathogenic mechanisms that influence neuronal viability. These mechanisms include oxidative stress, reduced antioxidant defence, neuroinflammation, altered neurotransmitter levels, protein accumulations, excitotoxicity, mitochondrial dysfunction, intracellular calcium level changes, and effects on neuronal histology, cognitive function, and animal behaviour. This implies that clinical and epidemiological studies are required to assess the potential neuronal harm arising from excessive intake of exogenous L-Glu.

Identifying non-hazardous substances in pharmaceutical manufacturing and setting default Health-Based Exposure Limits (HBELs)

Contract Development and Manufacturing Organizations (CDMOs) that manufacture large, diverse portfolio of chemical and pharmaceutical substances require pragmatic risk-based decisions with respect to the safe carry-over between different chemical entities, as well as for worker protection. Additionally, CDMOs may not have access to primary study data or data is generally lacking for a specific substance. While pharmaceuticals require the establishment of health-based exposure limits (HBELs) (e.g., occupational exposure limits, permitted daily exposure limits), the limits for non-hazardous substances could be set in a protective and pragmatic way by using default values, when internally required. Since there is no aligned definition provided by authorities, nor agreed default values for non-hazardous substances, we provide a decision tree in order to help qualified experts (such as qualified toxicologists) to identify the group of non-hazardous substances and to assign default HBEL values for specific routes of exposure. The non-hazardous substances discussed within this publication are part of the following subgroups: (I) inactive pharmaceutical ingredients, (II) pharmaceutical excipients or cosmetic ingredients, (III) substances Generally Recognized as Safe (GRAS), and (IV) food ingredients, additives and contact materials. The proposed default limit values are 1 mg/m³ for the OEL, and 50 mg/day for the PDE oral and IV (intravenous) route.

Liquid chromatography-Orbitrap Tribrid high-resolution mass spectrometry using data dependent-tandem mass spectrometry with triple stage fragmentation as a screening tool to perform identification and risk assessment of unknown substances in food contact epoxy resin

A new, fast, and automatic approach has been applied for the tentative identification of unknown substances released by food contact epoxy resin after performing a migration test with food simulant. This approach combines intelligent data acquisition with AcquireX linked to liquid chromatography-Orbitrap Tribrid high-resolution mass spectrometry using data dependent-tandem mass spectrometry with triple stage fragmentation coupled to Compound Discoverer™ software for automated data processing and compound identification. The identification of the observed features was performed using a set of identification criteria, including exact mass, isotope pattern, tandem mass spectrometry spectra match, and retention time. With these criteria, 263 substances were tentatively identified. Most of the identified compounds were additives, such as plasticisers, stabilizers, and antioxidants, used in different plastic applications. However, metabolites, biological constituents with pharmacological activity, and other substances with industrial applications were also detected. In order to perform a risk assessment of the food contact epoxy resin, threshold of toxicological concern approach was applied for the identified compounds. There was not risk associated with the migration of the identified substances.

Mechanisms of Food-Induced Symptom Induction and Dietary Management in Functional Dyspepsia

Functional dyspepsia (FD) is a common disorder of gut-brain interaction, characterised by upper gastrointestinal symptom profiles that differentiate FD from the irritable bowel syndrome (IBS), although the two conditions often co-exist. Despite food and eating being implicated in FD symptom induction, evidence-based guidance for dietetic management of FD is limited. The aim of this narrative review is to collate the possible mechanisms for eating-induced and food-related symptoms of FD for stratification of dietetic management. Specific carbohydrates, proteins and fats, or foods high in these macronutrients have all been reported as influencing FD symptom induction, with removal of 'trigger' foods or nutrients shown to alleviate symptoms. Food additives and natural food chemicals have also been implicated, but there is a lack of convincing evidence. Emerging evidence suggests the gastrointestinal microbiota is the primary interface between food and symptom induction in FD, and is therefore a research direction that warrants substantial attention. Objective markers of FD, along with more sensitive and specific dietary assessment tools will contribute to progressing towards evidence-based dietetic management of FD.

Differential effects of sodium chloride and monosodium glutamate on kidney of adult and aging mice

Monosodium Glutamate (MSG) is used as flavour enhancer, with potential beneficial effects due to its nutritional value. Given the decline in kidney functions during aging, we investigated the impact of MSG voluntary intake on the kidney of male mice, aged 6 or 18 months. For 2 months, they freely consumed water (control group), sodium chloride (0.3% NaCl) or MSG (1% MSG) in addition to standard diet. Young animals consuming sodium chloride presented signs of proteinuria, hyperfiltration, enhanced expression and excretion of Aquaporin 2 and initial degenerative reactions suggestive of fibrosis, while MSG-consuming mice were similar to controls. In old mice, aging-related effects including proteinuria and increased renal corpuscle volume were observed in all groups. At an advanced age, MSG caused no adverse effects on the kidney compared to controls, despite the presence of a sodium moiety, similar to sodium chloride. These data show that prolonged MSG intake in mice has less impact on kidney compared to sodium chloride, that already in young animals induced some effects on kidney, possibly related to hypertension.

APPLICATION OF THE IMPEDANCE METHOD FOR DETERMINATION OF MONOSODIUM GLUTAMATE IN FOOD PRODUCTS

The article presents the results of studying how impedance analysis can be used for determination of monosodium glutamate in order to identify food fraud. We have suggested that the parameters of complex conductivity (admittance) of a two-terminal circuit could allow detecting monosodium glutamate (E 621), an additive used in the food industry to enrich the taste. The method involves passing current of different frequencies through solid foodstuffs and a cell with liquid foodstuffs, measuring the electrical conductivity, and determining and analysing the frequency dependence of admittance. The active G component and the reactive B component of the admittance have been measured at different frequencies, from 100 Hz to 100 kHz. For the experiment, food samples were prepared in accordance with the Codex Alimentarius recommendations for the dosage of the food additive E 621: orange juice with monosodium glutamate added in the amount of 0.3%, and mashed potatoes with glutamate added in the amount of 1%, of the total weight of the products. The temperature of the tested products was 22 ± 0.2°С. The results of the studies have shown the dependences of the admittance components on the frequency for the control samples of juice and mashed potatoes and for the samples with monosodium glutamate added. The dependence of the active component and the reactive component of the foodstuff admittance have been established, with monosodium glutamate (added in the above-specified proportion) and without it. The difference is in how the dependences change in their nature. The monosodium glutamate curves both in juice and in mashed potatoes are similar. The samples containing monosodium glutamate have far higher values of the active and reactive admittance component than the control samples do, with a distinct peak of the reactive component characteristic. Therefore, impedance analysis is a possible method to detect quickly the flavour enhancer monosodium glutamate in foods of different consistency and thus identify food fraud.

Safety and efficacy of monosodium l-glutamate monohydrate produced by Corynebacterium glutamicum KCCM 80188 as a feed additive for all animal species

Following a request from the European Commission, the Panel on Additives and Products or substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of monosodium l‐glutamate monohydrate produced by fermentation using Corynebacterium glutamicum KCCM 80188 when used as a sensory additive (flavouring compound) in feed and water for drinking for all animal species. The production strain is not genetically modified. Viable cells of the production strain were not detected in the final additive. The additive does not give rise to any safety concern regarding the production strain. Monosodium l‐glutamate monohydrate produced using C. glutamicum KCCM 80188 is considered safe for the target species, for the consumer and for the environment. Monosodium l‐glutamate monohydrated produced by C. glutamicum KCCM 80188 is considered not toxic by inhalation, not irritant to skin or eyes and not a dermal sensitiser. The FEEDAP Panel expressed reservations on the use of the additive in water for drinking due to concerns on its impact on the hygienic conditions of the water. The Panel concluded that the additive is efficacious to contribute to the flavour of feed.

Safety and efficacy of l-glutamine produced using Corynebacterium glutamicum NITE BP-02524 for all animal species

Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of l-glutamine (≥ 98.0%) produced by fermentation using a genetically modified strain of Corynebacterium glutamicum (NITE BP-02524). It is intended to be used in feed for all animal species and categories as nutritional additive (amino acid) and as sensory additive (flavouring compound). Viable cells of the production strain and its recombinant DNA were not detected in the additive. l-Glutamine manufactured by fermentation using C. glutamicum NITE BP-02524 does not give rise to any safety concern with regard to the genetic modification of the production strain. The use of l-glutamine produced by fermentation using C. glutamicum NITE BP-02524 in animal nutrition is considered safe for all animal species when applied as a nutritional additive to achieve an adequate amino acid profile in feed and to overcome potential glutamine shortages during critical periods of life. The proposed use level (25 mg/kg feed) when used as sensory additive (flavouring compound) is safe for all animal species. The uses of l-glutamine produced using C. glutamicum NITE BP-02524 as nutritional additive or as flavouring compound are considered safe for the consumer. l-Glutamine produced using C. glutamicum NITE BP-02524 is not toxic by inhalation, is non-irritant to skin and eyes and is not a skin sensitiser. l-Glutamine produced using C. glutamicum NITE BP-02524 is considered safe for the environment. l-glutamine is a non-essential amino acid and it plays a physiological role as such. Recent evidence shows that glutamine may act as conditionally essential amino acid mainly in growing animals and has some specific effects e.g. in improving intestinal development and immune response. This amino acid produced by fermentation using C. glutamicum NITE BP-02524 is regarded as an efficacious source of glutamine for all animal species. For supplemental l-glutamine to be as efficacious in ruminants as in non-ruminants, it would require protection against degradation in the rumen. The use of l-glutamine as sensory additive at 25 mg/kg feed is considered efficacious.

In vitro genotoxicity assessment of monopotassium glutamate and magnesium diglutamate

Food additives are approved chemicals used for various purposes in foods; to provide nutritional safety, increase flavor, extend shelf life, reduce nutrient losses etc. In this study, the in vitro genotoxic effects of flavor enhancers, Monopotassium glutamate (MPG) and Magnesium diglutamate (MDG) were investigated in human peripheral blood lymphocytes by using chromosome aberrations (CAs), sister chromatid exchanges (SCEs), cytokinesis-block micronucleus cytome (CBMN-Cyt), and comet assays. Four concentrations of MPG (125, 250, 500, and 1000 μg/mL) and MDG (93.75, 187.5, 375, and 750 μg/mL) were used. Both food additives significantly reduced mitotic index and increased the frequency of CAs at high concentrations. MPG and MDG (except 93.75 μg/mL) significantly increased SCEs/Cell in concentration-dependent manner. In the CBMN-Cyt test, both MPG and MDG increased the formation of micronucleus, nuclear buds, and nucleoplasmic bridges compared to control in a concentration-dependent manner. However, these increases were statistically significant at higher concentrations. MPG (at 500 and 1000 μg/mL) and MDG (except 93.75 μg/mL) significantly increased DNA damages observed by comet assay. It is concluded from these results that MPG and MDG have clastogenic, mutagenic, aneugenic, and cytotoxic effects, particularly at high concentrations in human lymphocytes in vitro.

A review of the alleged health hazards of monosodium glutamate

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.