Update on food safety of monosodium l -glutamate (MSG)

Unraveling the MSG-Headache Controversy: an Updated Literature Review

PURPOSE OF REVIEW

To review the evidence and role of monosodium glutamate (MSG) as a headache and migraine trigger.

RECENT FINDINGS

MSG is a common food additive, has widely been linked as a trigger of headache, as well as other symptoms. However, the evidence for MSG as a causative agent for headache is debated. Various clinical trials over the past several decades have reported conflicting results, with studies suggesting that MSG does and does not increase the incidence of headache. However, the dosages of MSG exposure are often inconsistent across studies, with many studies administering a dose significantly higher than the average consumption.. Additionally, there are misconceptions about which foods and cuisines have MSG in them. MSG could be a potential trigger for migraine and headaches. It is unclear exactly how MSG plays into the migraine pathophysiology. It's crucial to accurately determine if MSG is present in one's diet to evaluate its potential impact on headaches.

A Study on the Awareness and Perceptions Regarding Monosodium Glutamate and its Potential Health Effects Amongst the Urban Population of Saudi Arabia

Introduction Monosodium glutamate (MSG), a common global food additive in processed foods, influences flavors and textures due to its chemical complexity and nutritional intricacy. Despite an annual production of 1.9 million tons and historical safety concerns, the multifaceted impact on health, ranging from metabolic disorders to neurological and cardiovascular implications, necessitates ongoing research for informed consumption and balanced dietary practices. Materials and methods This cross-sectional study investigates MSG-associated intricacies among Saudi Arabia's urban population. The research included questionnaire development, translation, and cultural adaptation, and was validated by nutrition experts. A sample size of 420 was calculated for a 95% confidence level. Data collection occurred from September 13 to October 31, 2023, and ethical considerations were ensured. Statistical analysis, including chi-square tests, regression analysis, and SPSS, explored intricacy relationships. Results The MSG intricacy study in Saudi Arabia's urban population, involving 420 respondents, showed statistically significant correlations (P < 0.05) in demographics. The key findings indicate an awareness of the impact of MSG on health, its associations with various conditions, and strong support for its exclusion from foods. Region, gender, age, and social status correlations highlighted diverse perspectives. The Western province showed the highest response rate at 42.61%, prompting regional awareness questions. Gender dynamics showed that 90.47% of the respondents were females, emphasizing potential gender-specific concerns. Concentration among ages 20-30 (61.9%) underscored generational factors. While commendable baseline awareness was noted, 73.09% of the participants believing MSG is harmful prompts further investigation. Emotional responses, including happiness (25.95%) and frustration (18.33%), highlight the complexity of the individuals' experiences, emphasizing the need for tailored communication strategies. Conclusion The MSG intricacy study in Saudi Arabia's urban population reveals insights into knowledge, attitudes, and behaviors, emphasizing the need for nuanced interventions considering regional and emotional differences. The findings underscore health concerns, supporting regulations, and knowledge impact on behavior. This survey serves as a valuable tool for informed public discourse and decision-making in the unique socio-cultural context of urban Saudi Arabia.

The interplay between monosodium glutamate (MSG) consumption and metabolic disorders

Monosodium glutamate (MSG) is one of the most popular food additives in the world and is often ingested with commercially processed foods. It can be described as a sodium salt of glutamic acid with the IUPAC name - Sodium 2-aminopentanedioate and is ionized by water to produce free sodium ions and glutamic acid. MSG use has significantly increased over the past 30 years, its global demand stands huge at over three million metric tons which is worth over $4.5 billion. Asia was responsible for more than three quarter of world MSG consumption with the country China also leading in global consumption as well as production and export to other countries. Prior to year 2020, global demand for MSG increased by almost four percent each year with the highest significant increase in demand for MSG predicted to rise in Thailand, Indonesia, Vietnam and China, followed by Brazil and Nigeria. However, several researches featured in this review has identified MSG consumption as a major contributor to the development and progression of some metabolic disorders such as obesity, which is a risk factor for other metabolic syndromes like hypertension, diabetes mellitus and cancer initiation. The mechanism by which MSG induce obesity involves induction of hypothalamic lesion, hyperlipidemia, oxidative stress, leptin resistance and increased expression of peroxisome proliferator-activated receptors (PPARs) Gamma and Alpha. Similarly for induction of diabetes mellitus, MSG consumption resulted in decreased pancreatic beta cell mass, increased oxidative stress and metabolic rates, reduced glucose and insulin transport to adipose tissue and skeletal muscles, insulin insensitivity, reduced insulin receptors and induced severe hyperinsulinemia. Dietary salt, an active component of MSG is also found to be a major risk factor for high blood pressure (which may lead to hypertension). MSG is used to enhance the taste of tobacco, causing smokers to consume the product in excess and thereby increasing the risk of cancer development. Depending on the amount consumed, MSG has both positive and negative effects. Despite the controversy surrounding MSG's safety and its probable contribution to risk of development and progression of metabolic disorders, its global consumption is still very high. Therefore, this article will sensitize the public on the need for cautious use of MSG in foods and also aid regulatory agencies to further review the daily MSG consumption limit based on metabolic toxicities observed at the varied dosages reported in this review.

Modelling of salt intake reduction by incorporation of umami substances into Japanese foods: a cross-sectional study

BACKGROUND

Evidence has demonstrated that excess sodium intake is associated with development of several non-communicable diseases. The main source of sodium is salt. Therefore, reducing salt intake in foods is an important global public health effort to achieve sodium reduction and improve health. This study aimed to model salt intake reduction with 'umami' substances among Japanese adults. The umami substances considered in this study include glutamate or monosodium glutamates (MSG), calcium diglutamate (CDG), inosinate, and guanylate.

METHODS

A total of 21,805 participants aged 57.8 years on average from the National Health and Nutrition Survey was used in the analysis. First, we employed a multivariable linear regression approach with overall salt intake (g/day) as a dependent variable, adjusting for food items and other covariates to estimate the contribution of salt intake from each food item that was selected through an extensive literature review. Assuming the participants already consume low-sodium products, we considered three scenarios in which salt intake could be reduced with the additional umami substances up to 30%, 60% and 100%. We estimated the total amount of population-level salt reduction for each scenario by age and gender. Under the 100% scenario, the Japan's achievement rates against the national and global salt intake reduction goals were also calculated.

RESULTS

Without compromising the taste, the 100% or universal incorporation of umami substances into food items reduced the salt intake of Japanese adults by 12.8-22.3% at the population-level average, which is equivalent to 1.27-2.22 g of salt reduction. The universal incorporation of umami substances into food items changed daily mean salt intake of the total population from 9.95 g to 7.73 g: 10.83 g to 8.40 g for men and 9.21 g to 7.17 g for women, respectively. This study suggested that approximately 60% of Japanese adults could achieve the national dietary goal of 8 g/day, while only 7.6% would meet the global recommendation of 5.0 g/day.

CONCLUSIONS

Our study provides essential information on the potential salt reduction with umami substances. The universal incorporation of umami substances into food items would enable the Japanese to achieve the national dietary goal. However, the reduced salt intake level still falls short of the global dietary recommendation.

Monosodium glutamate in a type 2 diabetes context: A large scoping review

This scoping review aimed to map and elaborate the heterogenous and inconclusive body of evidence relating monosodium glutamate (MSG) and type 2 diabetes (T2DM). For this reason, multiple health outcomes related to T2DM were included and a systematic search was conducted. Experimental and observational trials between 1995 and January 2021 were collected. The tests were highly heterogenous in their samples, doses, route of exposures, durations, diets and conclusions. There was a pattern of negative effects of MSG at oral doses ≥2,000 mg/kg of body weight, and by gavage or injection at any given dose. Evidence was lacking in many areas and most of the evidence relied on short term tests. Further research should focus on standardizing and justifying methodologies, conducting long term studies and toxicokinetic tests, and avoiding bias. Focusing on the gaps highlighted and investigating mechanisms of action of MSG is crucial. Evidence-based toxicology is encouraged.

Effect of Nigella sativa L. Seed on the Kidney of Monosodium Glutamate Challenged Rats

Monosodium glutamate (MSG) consumption is responsible for a wide spectrum of health hazards including nephrotoxicity. The search for phytochemical strategies having broad safety profile to counter MSG toxicity is worthwhile. Nigella sativa L. seed (NSS) is very promising in this regard owing to its antioxidant and cytoprotective nature. Therefore, we attempted to investigate the potential protective effect of NSS on MSG-induced renal toxicity in rats. To accomplish this objective, fifteen adult Wistar albino rats were randomly and equally divided into three groups for 21 days: the control group received no treatment, MSG group supplemented with MSG at a dose of 30 g/kg feed, and MSG + NSS group supplemented with MSG at the same previous dose in conjugation with NSS at a dose of 30 g/kg feed. MSG and its combination with NSS failed to cause any significant difference in the kidney function parameters in comparison with the control. A significant elevation in lipid peroxides (LPO) level, glutathione-S-transferase activity and total antioxidant capacity (TAC) and a significant reduction in superoxide dismutase activity were found in MSG group. LPO level and TAC in MSG intoxicated rats significantly normalized by NSS ingestion. NO level showed absence of significant difference among all experimental groups. MSG elicited histopathological lesions such as decreased glycoprotein content and fibrosis however, NSS succeeded in enhancing all these features. MSG group showed positive glutathione reductase and superoxide dismutase 2 immuno-expression whereas, MSG + NSS group showed weak immunostaining. A significant increase in the number of apoptotic cells was observed in MSG group compared to the control. On the other hand, MSG + NSS group exhibited a significant decrease in the number of apoptotic cells. NSS mitigated MSG-induced renal impairments by ameliorating oxidative stress and exerting anti-apoptotic effect.

The determination of the effect of in ovo administered monosodium glutamate on the embryonic development of thymus and bursa of Fabricius and percentages of alpha-naphthyl acetate esterase positive lymphocyte in chicken

Monosodium glutamate (MSG) is a flavor enhancer commonly used in modern nutrition. In this study, it was aimed to determine the effect of in ovo administered MSG on the embryonic development of thymus, bursa of Fabricius, and percentages of alpha-naphthyl acetate esterase (ANAE) positive lymphocyte by using histological, histometrical, and enzyme histochemical methods in chickens. For this purpose, 410 fertile eggs were used. The eggs were then divided into five groups: group 1 (control group, n = 40 eggs), group 2 (distilled water-injected group, n = 62 eggs), group 3 (0.12 mg/g egg MSG-injected group, n = 80 eggs), group 4 (0.6 mg/g egg MSG-injected group, n = 90 eggs), and group 5 (1.2 mg/g egg MSG-injected group, n = 138 eggs), and injections were performed via the egg yolk. On the 18th and 21st days of the incubation, the eggs were randomly opened from each group until six live embryos were obtained. The embryos of each group were sacrificed by decapitation, and blood, thymus, and bursa of Fabricius tissue samples were taken from the obtained embryos. The MSG-treated groups were found to be retarded embryonic development of thymus and bursa of Fabricius tissue compared to the control and distilled water groups. MSG treatment also resulted in reduced lymphoid follicles count and follicle diameters in bursa of Fabricius (P < 0.05). The percentage of peripheral blood ANAE positive lymphocytes was significantly lower in the MSG-treated groups than in the control and distilled water groups (P < 0.05). In conclusion, it has been found that in ovo administered MSG can adversely affect the embryonic development of thymus and bursa of Fabricius and decrease percentage of ANAE positive lymphocyte.

MONOSODYUM GLUTAMAT, LEZZET ARTTIRICI MI, ÖLDÜREN LEZZET Mİ?

Monosodium glutamat (MSG) 1800’lü yıllardan beri lezzet artırıcı katkı maddesi olarak, işlenmiş ve paketlenmiş tuzlu veya tatlı gıdalarda kullanılmaktadır. Yapılan birçok çalışma MSG kullanımının çok sayıda yapısal ve fonksiyonel bozukluklara yol açabileceğini ortaya çıkarmıştır. Son yıllarda MSG kullanımının çok artması gıda güvenliği konusunda endişelerinde artmasına neden olmuştur.

Protective Effects of Dietary Supplement Spirulina (Spirulina platensis) against Toxically Impacts of Monosodium Glutamate in Blood and Behavior of Swiss mouse

(1) Background: Well-known monosodium glutamate (E-621, MSG), originally used as a food flavor enhancer, was approved approximately in all countries, but the toxicity versus the safety of (MSG) are still unclear due to variable scientific toxicological reports. Moreover, it was reported to trigger elevated frequencies of nausea and headaches in humans and provide deleterious effects on laboratory animals. The objectives of the present study were to (i) estimate the possible toxic effects of the food additive MSG (ii) and the ameliorating protective effects of the dietary supplement spirulina (Spirulina platensis) on the biochemical parameters of blood and the damage produced in organs of Swiss mice after applying a supplementary daily dose of MSG for 4 weeks. (2) Methods: The present study was conducted on 20 mature Swiss mice, which were randomly organized into four groups of five Swiss mice. The treatments were (I) the control group, in which Swiss mice were fed only animal feed and drinking water; group II MSG1, which received 1 mL of MSG; group III MSG0.5, which was treated with 0.5 mL of MSG; and (IV) the group MSGS, which was treated with 1 mL of monosodium glutamate and 1 mL of spirulina (aiming to reduce the MSG toxicity). (3) Results: At the end of the experiment, Swiss mice treated with MSG demonstrated a passiveness regarding behavioral aspects. As we hypothesized, the parameters of the spirulina group reached similar values to the control group, and no histopathological observations have been found. Altogether, our findings evidenced that monosodium glutamate leads to histopathological changes in Swiss mice kidneys and caused important modifications for all biochemical parameters of the blood serum. Noticeably, the potential protective effect of Spirulina platensis was proved and was described by using the FTIR spectroscopy technique. (4) Conclusions: A diet rich in antioxidants and other plant-derived bioactive compounds may provide healthy nutrition, alleviating the potential side effects of some food additives.

Worldwide flavor enhancer monosodium glutamate combined with high lipid diet provokes metabolic alterations and systemic anomalies: An overview

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Flavor enhancing high lipid diet acts as silent killer.

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Monosodium glutamate mixed with high lipid diet alters redox-status.

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Monosodium glutamate mixed with high lipid diet induces systemic anomalies.

In this fast-food era, people depend on ready-made foods and engage in minimal physical activities that ultimately change their food habits. Majorities of such foods have harmful effects on human health due to higher percentages of saturated fatty acids, trans-fatty acids, and hydrogenated fats in the form of high lipid diet (HLD). Moreover, food manufacturers add monosodium glutamate (MSG) to enhance the taste and palatability of the HLD. Both MSG and HLD induce the generation of reactive oxygen species (ROS) and thereby alter the redox-homeostasis to cause systemic damage. However, MSG mixed HLD (MH) consumption leads to dyslipidemia, silently develops non-alcoholic fatty liver disease followed by metabolic alterations and systemic anomalies, even malignancies, via modulating different signaling pathways. This comprehensive review formulates health care strategies to create global awareness about the harmful impact of MH on the human body and recommends the daily consumption of more natural foods rich in antioxidants instead of toxic ingredients to counterbalance the MH-induced systemic anomalies.

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.

The Salt Flip: Sensory mitigation of salt (and sodium) reduction with monosodium glutamate (MSG) in "Better-for-You" foods

We tested the hypothesis that reduced-salt versions of four "better-for-you" dishes enhanced with monosodium glutamate (MSG) through a "Salt Flip" in an amount that still substantially reduced total sodium matched the consumer acceptance of normal-salt versions. Three versions each-standard recipe with normal salt, reduced salt, and reduced salt with MSG, of four dishes-roasted vegetables (RV), quinoa bowl (QB), savory yogurt dip (SD), and pork cauliflower fried rice (CR) were evaluated by 163 consumers for overall liking and liking of appearance, flavor, and texture/mouthfeel on the nine-point hedonic scale, preference, adequacy of flavor, saltiness, and aftertaste on just-about-right (JAR) scales, likeliness to order, and sensory characteristics by check-all-that-apply. For each dish, the MSG recipe was liked the same (or significantly more for SD, P < 0.05) than the standard recipe, and better than the reduced salt recipe for QB and CR. The same was true of likeliness to order. MSG recipes of QB and SD were significantly preferred to the standard recipes, with no difference for RV and CR. MSG recipes were consistently described as "delicious," "flavorful," and "balanced." Penalty-lift analysis showed that "delicious," "flavorful," "balanced," "fresh," and "savory"; and "bland," "rancid," and "bitter," were positive and negative drivers of liking, respectively. Two of three uncovered preference clusters, accounting for 68% of consumers, consistently liked MSG recipes, and the same or more so than standard recipes. We conclude that MSG can successfully be used to mitigate salt and sodium reduction without compromising consumer acceptance of better-for-you foods. PRACTICAL APPLICATION: The Salt Flip offers a promising dietary sodium reduction strategy through the addition of monosodium glutamate (MSG) to reduced-salt, savory, better-for-you foods that does not compromise consumer acceptance of their sensory profile.

Umami Ingredient: Flavor enhancer from shiitake (Lentinula edodes) byproducts

An alternative use of shiitake stipes, usually treated as waste, was proposed for the production of a powder ingredient, rich in umami compounds, aiming its application in food. The extraction of umami compounds was optimized through the Response Surface Methodology (RSM), in order to obtain an extract with high umami taste intensity. From the optimized condition, a comparative analysis of shiitake stipes dehydration method was performed. Stipes were dehydrated by hot air drying (HD) and freeze drying (FD), submitted to extraction and the umami compounds in the extracts were compared. The comparative analysis showed that the 5' - nucleotides are more sensitive to prolonged heating, while the release of free amino acids (FAA) was favored by hot air drying. The HD samples extract showed higher Equivalent Umami Concentration (EUC). The spray drying of the HD samples extract allowed the production of a newly powder ingredient rich in umami compounds (Umami Ingredient) that can be applied in diverse food matrices. Due to the presence of umami compounds, Umami Ingredient can be a potential alternative to help in the process of sodium reduction by enhancing food flavor.

Admissible daily intake for glutamate

PURPOSE OF REVIEW

Total glutamate (Glu) intake is 5-20 g/day in adults and about 40 mg/kg in breast-fed infant. Glu intake is constituted by Glu from protein and free Glu from certain foods and flavor-enhancing additive. The admissible intake of free Glu additive is addressed.

RECENT FINDING

In the gut, Glu is actively metabolized by enterocytes and because of this metabolism, the systemic availability of ingested Glu remains relatively low. Human studies are preferred to assess the transfer in blood of dietary free Glu salts and their possible risks. When human data are not available, experimental animal models provide the basis to assess the risks to humans but toxicity studies in rodents remain for a part controversial. A No Observable Adverse Effect Level (NOAEL) in rodent of 3200 mg/kg/day and an uncertainty factor of 100 lead to an acceptable daily intake (ADI) of 30 mg/kg/day for free Glu salts used as additives, whereas a NOAEL higher than 6000 mg/kg/day and an uncertainty factor of 25 leads to an ADI of 240 mg/kg/day for free Glu salts.

SUMMARY

Current discussions indicate an ADI from 30 to 240 mg/kg/day depending on the chosen NOAEL in animal model and compound-specific uncertainty factor (from 25 to 100).

Cortical tau burden and behavioural dysfunctions in mice exposed to monosodium glutamate in early life

Although monosodium glutamate (MSG)-induced neurotoxicity has been recognized for decades, the potential similarities of the MSG model to Alzheimer’s disease (AD)-type neuropathology have only recently been investigated. MSG-treated mice were examined behaviourally and histologically in relation to some features of AD. Four-week old mice received 5 subcutaneous MSG (2 g/kg) injections on alternate days, or saline. At age 10–12 weeks, they were given a battery of behavioural tests for species-typical behaviours and working memory. The mice were killed at 12 weeks and the brains excised. Accumulation of hyperphosphorylated tau protein was assessed in cortical and hippocampal neurons by immunohistochemistry, and in cerebral cortical homogenates. A 78% increase in cortical concentrations of phosphorylated tau protein was observed in the MSG mice. Intracellular hyperphosphorylated tau immunostaining was observed diffusely in the cortex and hippocampus, together with cortical atrophic neurons, extensive vacuolation and dysmorphic neuropil suggestive of spongiform neurodegeneration. Nest-building was significantly impaired, and spontaneous T-maze alternation was reduced, suggesting defective short-term working memory. Subcutaneous MSG treatment also induced a 56% reduction in exploratory head dips in a holeboard (P = 0.009), and a non-significant tendency for decreased burrowing behaviour (P = 0.085). These effects occurred in the absence of MSG-induced obesity or gross locomotor deficits. The findings point to subcutaneous MSG administration in early life as a cause of tau pathology and compromised species-typical behaviour in rodents. Determining whether MSG can be useful in modelling AD requires further studies of longer duration and full behavioural characterization.

Effect of monosodium glutamate on growth performance and blood biochemical parameters of rainbow trout (Oncorhynchus mykiss W.)

Aim:

This study aimed to evaluate the effect of dietary monosodium glutamate (MSG) on growth performance and blood biochemical parameters of rainbow trout (Oncorhynchus mykiss W.).

Materials and Methods:

A total of 200 trouts were allotted in five experimental groups (n=40) that for 60 days received feed supplemented with MSG at the following levels: 0% (K) or 0.5% (E) or 1% (F) or 3% (G) or 5% (H).

Results:

The average initial weight of trouts was 116.68±1.51 g (K), 116.58±1.33 g (E), 116.43±1.39 g (F), 117.40±1.47 g (G), and 115.95±1.88 g (H). At the end of the trial, control fish (K) had the lowest live weight (242.90±3.87 g) compared to Groups E (252.70±5.69 g), F (250.93±4.82 g), G (248.25±4.98 g), and H (247.95±4.74 g). Feed conversion ratio (FCR) of control group (K) was higher (1.11±0.02) versus FCR values established in Groups E (1.03±0.01), F (1.04±0.02), G (1.07±0.03), and H (1.06±0.02). Albumin, aspartate aminotransferase, gamma-glutamyl transpeptidase, alkaline phosphatase, phosphorus, magnesium, and triglyceride exhibited statistically significant differences versus controls.

Conclusion:

The results from the study showed that dietary supplementation of rainbow trouts with MSG increased live weight and reduced FCR. The optimum level of MSG recommended for addition to feed was 0.5%.

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.

Effects of monosodium glutamate on apoptosis of germ cells in testicular tissue of adult rat: An experimental study

Background

Monosodium glutamate (MSG) is used as a flavoring and food seasoning. Some studies have reported the oxidative effects of using this substance on various tissues.

Objective

This study has investigated the effects of MSG and the protective effect of vitamin C (vit C) on apoptosis of testicular germ cells and biochemical factors.

Materials and Methods

In this experimental study, 24 adult male Wistar rats were randomly divided into four groups: control (received distilled water), vit C group (150 mg/kg), experimental group 1 (MSG 3 gr/kg), experimental group 2 (MSG 3 gr/kg + vit C 150 mg/kg). The rats were gavaged for 30 days, and then were sacrificed, the right testis was isolated for biochemical examinations for the glutathione, malondialdehyde, and left testis used in histological experiments. Tunnel staining was used to determine the number of apoptotic cells.

Results

The results showed that apoptotic cells in the MSG group had a significant increase compared to the control group (P = 0.001), but the number of these cells in the MSG co-administered with vit C and vit C groups were significantly lower than the MSG group. Germinal epithelial thickness also decreased in MSG group compared to the control group.

Conclusion

MSG can lead to increase apoptotic changes in the germinal epithelial of the testicle, and vit C as an antioxidant can modify the pathological and biochemical changes induced by MSG.

Dietary free glutamate comes from a variety of food products in the United States

Glutamate is naturally present in various foods, such as many savory foods. Therefore, we hypothesized that dietary free glutamate comes from a variety of foods in the United States. The aims of this study were to develop a naturally-occurring free glutamate composition database, in addition to further estimate dietary intake and identify major food sources of free glutamate in US children and adults. The composition database of free glutamate was developed based on analytical values obtained from food analysis and available literature. This database was applied to dietary data obtained from a 24-h dietary recall among 8597 children (2-19 y) and 13 969 adults (≥20 y) in the National Health and Nutrition Examination Survey (2009-2014) to estimate dietary intake and major food sources of free glutamate. Mean intake of free glutamate for children and adults was 258 mg/d (136 mg/1000 kcal) and 322 mg/d (155 mg/1000 kcal), respectively. According to the What We Eat in America category, major food sources of free glutamate were fruits (9.3%), condiments and sauces (9.0%), and mixed dishes-grain based (8.1%) for children and vegetables-excluding potatoes (13.6%), mixed dishes-meat, poultry, seafood (8.5%), and condiments and sauces (7.8%) for adults. For both children and adults, the top food sources included watermelon, raw; tomato catsup; tomatoes, raw; and roll, white, soft. To our knowledge, this is the first study to provide valuable data regarding intake of naturally-occurring free glutamate in foods. We found that dietary free glutamate comes from various foods in the US population, not exclusively from protein-rich foods.

Resistance training restores metabolic alterations induced by monosodium glutamate in a sex-dependent manner in male and female rats

Despite resistance exercises being associated with health outcomes, numerous issues are still unresolved and further research is required before the exercise can faithfully be prescribed as medicine. The goal of this study was to investigate whether there are sex differences in resistance training effects on metabolic alterations induced by monosodium glutamate (MSG), a model of obesity, in male and female rats. Male and female Wistar rats received MSG (4 g/kg body weight/day, s.c.) from postnatal day 1 to 10. After 10 days from MSG administration, the rats were separated into two groups: MSG-sedentary and MSG-exercised. At postnatal day 60, the animals started a resistance training protocol in an 80 degrees inclined vertical ladder apparatus and performed it for 7 weeks. Control rats received saline solution and were divided in saline-sedentary and saline-exercised. Resistance training restored all plasma biochemical parameters (glucose, cholesterol, triglycerides, aspartate aminotransferase, and alanine aminotransferase) increased in male and female rats treated with MSG. The MSG administration induced hyperglycemia associated with a decrease in the skeletal muscle glucose transporter 4 (GLUT4) levels and accompanied by deregulation in proteins, G-6Pase, and tyrosine aminotransferase, involved in hepatic glucose metabolism of male and female rats. MSG induced dyslipidemia and lipotoxicity in the liver and skeletal muscle of male rats. Regarding female rats, lipotoxicity was found only in the skeletal muscle. The resistance training had beneficial effects against metabolic alterations induced by MSG in male and female rats, through regulation of proteins (GLUT2, protein kinase B, and GLUT4) involved in glucose and lipid pathways in the liver and skeletal muscle.

The Role of the Japanese Traditional Diet in Healthy and Sustainable Dietary Patterns around the World

As incomes steadily increase globally, traditional diets have been displaced by diets that are usually animal-based with a high content of “empty calories” or refined sugars, refined fats, and alcohol. Dietary transition coupled with the expansion of urbanization and lower physical activity have been linked to the global growth in the prevalence of obesity, overweight and life style-related non-communicable diseases. The challenge is in how to reverse the trend of high consumption of less healthy food by more healthful and more environmentally sustainable diets. The increasing recognition that each individual has specific needs depending on age, metabolic condition, and genetic profile adds complexity to general nutritional considerations. If we were to promote the consumption of low-energy and low salt but nutritious diets, taste becomes a relevant food quality. The Japanese traditional diet (Washoku), which is characterized by high consumption of fish and soybean products and low consumption of animal fat and meat, relies on the effective use of umami taste to enhance palatability. There may be a link between Washoku and the longevity of the people in Japan. Thus Washoku and umami may be valuable tools to support healthy eating.