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Effects of monosodium glutamate (MSG) on human health: a systematic review

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  • Universal College of Medical Sciences, Nepal

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*Corresponding Author Address: Dr. Tushar Kanti Bera,, Assistant Professor, Department of Physiology, Universal College of Medical
Sciences, Bhairahawa, Lumbini Zone, Nepal; Email: tusharvu_kanti@yahoo.co.in
World Journal of Pharmaceutical Sciences
ISSN (Print): 2321-3310; ISSN (Online): 2321-3086
Published by Atom and Cell Publishers © All Rights Reserved
Available online at: http://www.wjpsonline.org/
Review Article
Effects of monosodium glutamate on human health: A systematic review
Tushar Kanti Bera*, Sanjit Kumar Kar, Prem Kumar Yadav, Prithwiraj Mukherjee, Shankar Yadav, Bishal
Joshi
Department of Physiology, Universal College of Medical Sciences, Bhairahawa, Lumbini Zone, Nepal
Received: 03-03-2017 / Revised: 30-03-2017 / Accepted: 17-04-2017 / Published: 26-04-2017
ABSTRACT
Monosodium glutamate (MSG) is one of several forms of glutamic acid found in foods, in large part because
glutamic acid (an amino acid) is pervasive in nature. MSG is used in the food industry as a flavor enhancer with
an umami taste that intensifies the meaty, savory flavor of food, as naturally occurring glutamate does in foods
such as stews and meat soups. MSG has been used for more than 100 years to season food, with a number of
studies conducted on its safety. Under normal conditions, humans can metabolize relatively large quantities of
glutamate, which is naturally produced in the gut by exopeptidase enzymes in the course of protein hydrolysis.
The median lethal dose (LD50) is between 15 and 18 g/kg body weight in mice and rats, respectively, five times
greater than the LD50 of salt (3 g/kg in rats). The use of MSG as a food additive and the natural level of glutamic
acid in foods are not toxicological concerns in humans. The U.S. Food and Drug Administration have given
MSG it’s generally recognized as safe (GRAS) designation. A popular belief is that large doses of MSG can
cause headaches and other feelings of discomfort, known as ‘Chinese Restaurant Syndrome’ (CRS), but double-
blind tests fail to find evidence of such a reaction. The European Union classifies it as a food additive permitted
in certain foods and subject to quantitative limits.
Keywords: MSG, Chinese restaurant syndrome, oxidative stress, appetite enhancer, oral care
INTRODUCTION
Foods have two main functions, i.e. they provide
nutrition and an occasion for a pleasurable social
event. Both functions are fulfilled only if a food is
actually consumed. A food composed of the
nutritional elements required for an optimal diet
that is unattractive and thus not consumed provides
no nutrition. Flavouring systems are of vital
importance in savoury food manufacturing. Many
industrially prepared foods are particularly
attractive to potential consumers primarily because
of their typical flavours. Therefore it's no surprise
that the food industry dealing with these product
segments shows great interest in the use of food or
food ingredients carrying the typical umami taste
and flavour enhancement systems. Flavourings can
play an important nutritional role, particularly in
foods that are not very flavourful, by providing the
needed appeal. Monosodium glutamate (MSG) is
the sodium salt of the amino acid glutamic acid.
Glutamic acid or glutamate is one of the most
common amino acids found in nature. It is the main
component of many proteins and peptides, and is
present in most tissues. It is made commercially by
the fermentation of molasses, but exists in many
products made from fermented proteins, such as
soy sauce and hydrolyzed vegetable protein.
Glutamate is also produced in the body and plays
an essential role in human metabolism [1]. It is a
major component of many protein-rich food
products such as meat, fish, milk and some
vegetables. However, only the free form of
glutamic acid or glutamates has an effect on the
glutamate receptors. When bound to other amino
acids in a protein, it does not stimulate glutamate
receptors. They become partially free during
processing, thereby accentuating their characteristic
flavor properties [2, 3]. The two isomers of
monosodium glutamate are L-glutamate
enantiomer and D-glutamate enantiomer. Only the
L-glutamate enantiomer has flavor-enhancing
properties. Manufactured monosodium glutamate
contains over 99.6% of the naturally predominant
L-glutamate form, which is a higher proportion of
L-glutamate than found in the free glutamate ions
of naturally occurring foods [4].
HISTORY
Glutamic acid was discovered and identified in
1866 by the German chemist Karl Heinrich
Bera et al., World J Pharm Sci 2017; 5(5): 139-144
140
Ritthausen, who treated wheat gluten with
sulphuric acid [5]. Kikunae Ikeda of Tokyo
Imperial University isolated glutamic acid as a taste
substance in 1908 from the seaweed Laminaria
japonica (Kombu) by aqueous extraction and
crystallization, calling its taste umami. Ikeda
noticed that dashi, the Japanese broth of
katsuobushi and kombu, had a unique taste not yet
scientifically described (not sweet, salty, sour, or
bitter) [6]. To verify that ionized glutamate was
responsible for umami, he studied the taste
properties of glutamate salts: calcium, potassium,
ammonium, and magnesium glutamate. All these
salts elicited umami and a metallic taste due to the
other minerals. Of them, sodium glutamate was the
most soluble and palatable and the easiest to
crystallize. Ikeda called his product ‘monosodium
glutamate’, and submitted a patent to produce
MSG; the Suzuki brothers began commercial
production of MSG in 1909 as Aji-no-moto
(essence of taste) [5, 7]. The level of glutamates
and free amino acids increases considerably after
ripening or seasoning of certain foods. Especially
certain cheeses due their taste and texture to long
ripening, which increases the presence of amino
acids. These products are often used to enhance the
flavor of meat dishes (Table-1).
Table 1: Natural glutamate content of fresh food -the values is expressed in mg/100g food [8].
Types of Foods
Bound glutamate
Free glutamate
Milk/Milk products
Cow
819
2
Human
229
22
Parmesan Cheese
9.847
1200
Poultry products
Eggs
1.583
23
Chicken
3.309
44
Duck
3.636
69
Meat
Beef
2.846
33
Pork
2.325
23
Fish
Cod
2.101
9
Mackerel
2.382
36
Salmon
2.216
20
Vegetables
Peas
5.583
200
Corn
1.765
130
Beets
256
30
Carrots
218
33
Tomatoes
238
140
PROPERTIES OF MSG
Monosodium glutamate (MSG, also known as
sodium glutamate; IUPAC name- Sodium 2-
aminopentanedioate) is the sodium salt of glutamic
acid, one of the most abundant naturally occurring
non-essential amino acids (Fig. 1). The tongue is
sensitive to five flavors- salt, sweet, bitter, sour,
and umami in the Japanese language, the taste of
MSG. ‘Umami’ is used by the Japanese to describe
the taste of MSG as well as the meaty taste of
certain fish and broth [9]. The substances which
constitute the umami taste can be divided in two
main groups.
One is the -amino acid group, represented
by monosodium glutamate.
5'-nucleotid group, represented by inosine
5'-monophosphate (IMP) and guanosine mono
phosphate (GMP) and their derivatives [10].
Figure 1: Chemical structure of
Monosodium Glutamate
Bera et al., World J Pharm Sci 2017; 5(5): 139-144
141
Food palatability increases with appropriate
concentrations of MSG [11]. The basic sensory
function of MSG is attributed to its ability to
enhance the presence of other taste-active
compounds. Ideal serum levels of Glutamine to
Glutamate appear to be 9 parts Glutamine to 1 part
Glutamate, which is mediated by enzymatic
conversion in various parts of the body as required
by fluctuating levels. When enzyme function is
depressed or electrolytes are deficiency-stressed in
the presence of too much glutamate to too little
glutamine the optimal ratio fails to support aerobic
metabolism. This is the reason why athletes need to
read the labels and consider reducing MSG from
their diet. ‘Monosodium Glutamate’ appears on
labels as "MSG", ‘contains glutamate’,
‘hydrosolated’, or simply a processed protein that
contains "Glutamate", should be limited. Simplified
summary of glutamic acid, glutamate, and
glutamine pathway [2].
AMMONIA + GLUTAMINE
GLUTAMINE SYNTHASE ENZYME
GLUTAMATE GLUTAMINE (BRAIN) CONVERSION
GABA or GLUTAMATE
ENERGY + GLUTATHIONE + NIACIN GLUTAMINE SYNTHASE
GLUTAMATE OR GABA
GLUTAMINE [SCAVENGES AMMONIA]
GLUTAMINE
GLUTAMATE
GABA
GLUTAMINE
EFFECTS OF MONOSODIUM GLUTAMATE
(MSG)
MSG on oxidative stress: More recent studies
have examined other metabolic and toxic effects of
MSG, with a number of the reports showing that
showing the induction of oxidative stress in
different tissues of experimental animals after
administration of chronic doses of MSG [12-14].
Glutamic acid has been suggested as one of the
amino acids utilized by the kidney during
gluconeogenesis since the net uptake of important
gluconeogenic precursors such as lactate, glycerol,
glutamate, glutamine and other amino acids by the
kidney accounts for the turnover of glucose by the
kidney [15]. Increased influx of substances into the
kidney has been associated with various changes
and oxidative stress [14]. This has been
corroborated in more recent reports in which
hyperglycemia caused oxidative stress in the
kidney via the formation of free radicals and altered
the antioxidant reactions catalyzed by ROS
scavenging enzymes [16]. Hyperglycemia is also
known to increase glucose auto-oxidation and
labile glycation or intracellular activation of the
polyol pathway, with the subsequent oxidative
degradation of the glycated protein enhancing the
production of reactive oxygen species [16].
Monosodium glutamate causes obesity: MSG
may influence you to overeat, leading to obesity.
Researchers from the University of North Carolina
did a study among people in rural China to examine
the effects of MSG. They chose that region because
most people there prepare their meals at home
without processed foods but still use a lot of MSG.
Those who used the most MSG were also the most
likely to be overweight, regardless of how their
total calories and levels of physical activity
Bera et al., World J Pharm Sci 2017; 5(5): 139-144
142
compared with those who used the least. In other
studies, mice are injected with MSG for the very
purpose of causing them to become obese.
Scientists think MSG causes lesions in the brain
and interferes with its processing leptin [17, 18].
Leptin is a hormone that signals to the brain that
you have had enough to eat, and it shuts off your
appetite and increases your calorie-burning.
Problems with leptin signaling, called leptin
resistance, are factors in obesity.
Monosodium glutamate and cancer: According
to the American Institute for Cancer Research,
studies to uncover MSG's potential ill effects began
in the late 1960s. At that time, some people began
to believe that the additive in dishes they ate at
Chinese restaurants made them sick. Since that
time, scientists have looked and have not found a
link between monosodium glutamate and cancer
[19]. Katherine Zeratsky, a registered and licensed
dietitian with Mayo Clinic, says that people's
complaints about monosodium glutamate vary.
Some say they develop headaches or nausea while
others feel flushed after eating it. Accelerated
heartbeat, chest pain and weakness also are some of
the reactions individuals associate with MSG.
There also are those who say they begin to sweat or
feel a certain pressure or numbness in the face
when exposed to the food additive. The U.S. Food
and Drug Administration requires manufacturers to
indicate on the label that a product has MSG. Read
the list of ingredients before buying canned and
other processed goods. If you have a history of
reacting to monosodium glutamate, do not buy
anything that lists it as an ingredient.
Monosodium glutamate poisoning: Other terms
for MSG are Chinese restaurant syndrome,
glutamate-induced asthma, hot dog headache and
MSG syndrome. The term ‘Chinese restaurant
syndrome’ was first used in the 1960s to describe
the symptoms experienced by some people after
eating in Chinese restaurants. Monosodium
glutamate poisoning refers to a cluster of symptoms
recognized as an adverse reaction to MSG. The
symptoms include headache, sweating, flushing,
heart palpitations, weakness, chest pain and nausea
[20]. Other symptoms are tightness in the face and
burning, numbness and tingling in the face and
neck.
MSG on pregnant and lactating women: It is
common practice for expectant women to eat a
varied and well-balanced diet and consume enough
calories to ensure a healthy pregnancy. To facilitate
fetal growth and development, most amino acids
are actively transported across the placenta.
Research indicates that amino acid concentrations
are higher in the fetus, regardless of what the
mother consumes [21]. Both the placenta and fetal
liver play important roles in amino acid (and
specifically glutamate) transport and metabolism
important for fetal development [22]. In rodent
studies, researchers investigated effects of dietary
intake of MSG on reproduction and birth. The
study looked at three generations of mice that were
fed a daily intake of up to 7.2 g/kg of MSG. No
adverse effect was observed in each generation, nor
was there evidence of any incident of brain lesions
in the neonates.
Besides research on the fetus, scientists also
investigated the effect of MSG ingestion on
lactation and breast-fed infants. Upon examination
of lactating women who consumed MSG at 100
mg/kg of body weight, researchers noticed no
increase in the level of glutamate in human milk,
and no effect on the infant’s intake of glutamate.
According to Baker and colleagues, a newborn
infant, through breastfeeding, ingests more free
glutamate per kilogram of body weight than during
any other period of its life. American Academy of
Pediatrics Committee stated that MSG has no effect
on lactation and poses no risk to the consuming
infant [23].
MSG on children: It has been speculated that
children would metabolize oral MSG more slowly
than adults. However, research conducted by
Stegink and colleagues at the University of Iowa
showed that children as young as one year old
metabolize glutamate as effectively as adults. In the
study, infants were fed beef consommé providing
MSG at various dosage levels of 0, 25 and 50
mg/kg of body weight. Researchers measured the
infant’s plasma glutamate levels and, after
comparing the children’s plasma levels to those of
adults, found no higher plasma glutamate values
for children [24]. Additionally, scientific evidence
has not implicated MSG in attention deficit
hyperactivity disorder or other behavioral problems
in children. For the general population, MSG does
not pose a health risk [25]. Based on the scientific
evidence upholding the safety and efficacy of
MSG, the Select Committee on GRAS Substances
(SCOGS) concluded in 1980 that there is no
evidence that demonstrates reasonable grounds to
suspect a hazard to the public when glutamic acid
or its salts are used at current levels and manners
now practiced [26].
MSG and neurological effects: MSG is a well-
known compound in research circles used to fatten
up rats for experimentation, because it dramatically
increases insulin production. According to
‘Contemporary Nutrition,’ the food additive
industry readily admits that MSG has addictive
properties and can cause people to gain weight, but
Bera et al., World J Pharm Sci 2017; 5(5): 139-144
143
they justify its use by claiming that this can be
beneficial to elderly persons who are sometimes
malnourished. Glutamate, the main component of
MSG, is the primary excitatory neurotransmitter in
the brain, and it has been linked to neurological
symptoms when taken in excess [27, 28].
Neurotransmitters, such as glutamate, are important
for chemical communication in the brain, where
they are very carefully balanced and managed.
Excessive quantities of a neurotransmitter,
however, can cause it to become an excitotoxin, a
substance that over-excites cells to the point of
damage, when the balance of glutamate is upset
this substance can become neurotoxic, leading to
enzymatic cascades resulting in cell death [29].
Neurological conditions that some researchers
claim may be associated with MSG include
migraines, seizures, autism, attention deficit
disorder, hyperactivity, Alzheimer's disease, Lou
Gehrig's disease, multiple sclerosis and Parkinson's
disease. However, according to a 2007 issue of the
‘European Journal of Clinical Nutrition,’ an
international team of experts concluded that MSG
was "harmless for the whole population." They
declared that 16 mg/kg of body weight per day was
the safe limit for MSG consumption [30].
MSG as an appetite enhancer: MSG is used
extensively throughout the world as a flavor
enhancer. It improves such specific flavor
characteristics of food as continuity, mouth
fullness, mildness, and thickness of food. It also
improves the overall preference for food. In the
elderly, there is a general decrease in the sensitivity
of the senses, including taste. Several such reports
have described the taste threshold to MSG in
elderly people in Western countries; however, few
data have evaluated changes in elderly people in
Asian countries [31]. A recent study reported the
sensitivity and preference for L-glutamate (umami
taste) in middle-aged and elderly Japanese women.
Similar to findings in Western individuals, the
threshold and preferred concentrations of L-
glutamate were significantly higher in elderly
Japanese women than in middle aged Japanese
women [32]. L-Glutamate (umami taste) preference
varies under different physiologic conditions. The
preference for umami is affected by nutritional
status. For example, poorly nourished subjects
prefer foods with a higher MSG concentration than
do well-nourished subjects [11]. It was reported
that umami taste sensitivity is correlated with the
protein preference score, suggesting that the taste
threshold for umami predicts one’s liking as well as
preference for high-protein foods.
Oral care effect of MSG: Eating is one of the
great pleasures in life. Optimal nutrition, appetite
satisfactions are of paramount importance in the
elderly. When food is ingested, saliva acts not only
as a solvent that allows tastants to be extracted
from foods but also as a glue and lubricant for
masticated foods that permits safe swallowing.
Furthermore, saliva is important for the dental
health (lubrication and mineralization), immune
function, and prevention of microbial growth [33].
Salivary secretion is provoked by mechanical
(mastication and speech) and gustatory stimuli, as
well as the autonomic nerves [34]. Kawamura et al
and Horio and Kawamura reported that umami
taste stimuli increase salivary flow in healthy adult
subjects. According to one study, next to sour taste,
umami taste is the most potent taste stimulus of
saliva secretion from the parotid gland. In addition,
of the 5 basic tastes, the increase in salivary
secretion produced by umami is the most long
lasting [35]. Schiffman and Miletic have measured
the influence of umami taste on the amount of
immunoglobulin A in the saliva (sIgA) secreted by
elderly subjects ingesting food. The ingestion of a
food containing added MSG was observed to
produce significantly more saliva secretion than
occurred after ingesting the same food with no
added MSG. Salivary sIgA concentration was not
different; hence, the oral cavity experienced a
greater total exposure to secreted sIgA when MSG
was present in the food [36]. The ability of umami
to increase salivary flow may therefore have
clinical potential in the elderly, who frequently
experience dry mouth and its complications.
CONCLUSION
It is apparent that there is no shortage of research
conducted on this ubiquitous ingredient and its
potential health effects. Because MSG is one of the
most intensely studied food ingredients in the food
supply and has been found safe, the Joint Expert
Committee on Food Additives of the United
Nations Food and Agriculture Organization and
World Health Organization placed it in the safest
category for food additives. United States food and
drug administration (FDA) concluded that MSG is
safe when ‘eaten at customary levels’ and, although
a subgroup of otherwise healthy individuals
develop an MSG symptom complex when exposed
to 3 g of MSG in the absence of food, MSG as a
cause has not been established because the
symptom reports are anecdotal. International and
national bodies governing food additives currently
consider MSG safe for human consumption as a
flavor enhancer.
Bera et al., World J Pharm Sci 2017; 5(5): 139-144
144
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... Earlier studies have correlated MSG to malnutrition and behavior disturbance [11], but the pathological mechanism mediating this effect is poorly understood. Therefore, to our knowledge, the current study is the first to explore the association between MSG, mal-nutrition and ADHD behavior disturbance in attempt to determine the nutritive importance in such disorder alongside the possible mechanistic pathway of MH as neuroprotective agent. ...
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... According to the chemical formula, monosodium glutamate is divided into two, namely 2-aminopentanedioc and 2-amino glutamic acid. Consuming MSG in excess can cause toxic effects, CNS disorders, obesity, disturbances in adipose tissue physiology, liver damage, and reproductive dysfunction that was reported by the studies of [5][6][7][8]. Meanwhile, the amount of MSG consumption in the body needs to be controlled to maintain the health of the human body. ...
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... Dose concentrations were selected based on the median lethal dose 50 (LD50) (9), for MSG (10), and NaNO2 (11), which are: 12 g/kg body weight for MSG, and the dose administered in 0.5 ml of distilled water through mouth by gavage needle, and 120 mg/kg body weight for NaNO2, in 0.2 ml of distilled water by injection intraperitoneal. ...
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Food additives and preservatives are widely used globally, which, despite their many benefits, have great harm if they are used without health restrictions or control, as they cause many health problems and tissue lesions. Therefore, the present study aimed to investigate the histopathological effects on the lung of pregnant rats of two types of these substances: Monosodium glutamate (MSG) and Sodium nitrite (NaNO2). Twenty-four pregnant rats used for this study, and they were divided into four groups equally. The control group was dosed with distilled water from the sixth day to the fifteenth day of pregnancy. The second was dosed with MSG at a 12g /kg concentration for the same period in the first group. The third injected with a concentration of 120 mg/kg of NaNO2 for the same period. The fourth was dosed with MSG and NaNO2 together, with the same concentrations and the above period. The results showed that the second group''s lungs showed many histopathological changes, including strong infiltration of inflammatory cells, congestion of blood vessels, necrosis of bronchioles and alveolar septa, and emphysema of some alveoli. In the third group, changes included hyperplasia of the fibroblasts, hemorrhage in the alveoli, desquamation and necrosis in bronchioles, peri-bronchial fibrosis, blood vessel congestion. The fourth group showed infiltration of inflammatory cells, necrosis in multiple lung areas, emphysema, fibrosis in some alveoli, and hypoplasia of the muscle fibers around the blood vessels. The study concluded that MSG and NaNO2 caused much tissue damage in the lungs of pregnant rats.
... MSG is formed from H2O, sodium, and glutamate, and it's a chief food taste enhancer, which improves to overstate the inherent flavor of foods (Kayode et al., 2020). Moreover, MSG is a subset of glutamate which is an important but non-vital amino acid that has an important role in human metabolism (Bera et al., 2017). It may be used in packaged foods involving beef, milk, tuna, and vegetables. ...
... Umami flavors are produced by MSG (Monosodium Glutamate) which is a synthetic flavoring ingredient. The safe limit of consumption of Monosodium Glutamate according to [1] is 16 mg/kg of body weight per day. According to [2] quoted [3]. the consumption of Monosodium Glutamate in large quantities can cause nerve cell damage in the brain. ...
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The consumption of Monosodium Glutamate with a large amount can lead to nerve cell damage to the brain so that natural ingredients substitute MSG is needed. In this research, we produced smart flavors from catfish through enzymatic hydrolysis by combining papain and biduri enzymes. The purpose of the study was to identify the influence of enzyme concentration and length of hydrolysis on the smart flavor characteristics and determine the best treatment to produce smart flavors. The parameters identified were color, yield, moisture content, dissolved proteins, degrees of hydrolysis, antioxidants, water binding ability, and emulsion stability. The results show the highest brightness are biduri and papain combination by 60:40 with one-hour hydrolysis. The highest dissolved protein is 50:50 combination with three-hour hydrolysis. In addition, antioxidant activity is marked in a combination of 50:50 with one-hour hydrolysis.
... • Choosing of doses Concentration used in the study The dose concentrations were selected in light of the median lethal dose 50 (LD50) for MSG ranging from 15-18 g/kg B.W. [16] and for NaNO2 ranging from 85-150 mg/kg B.W. [17]. The doses that were used in this study were as following: (9 g / kg) MSG, the dose was administered in 0.5 ml D.W. orally by the Gavage needle, and (110 mg/kg) for NaNO2 in 0.1 ml D.W. was given as intraperitoneal (I.P.) injection. ...
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The present study aimed to discover the histopathological of the Monosodium glutamate (MSG), and Sodium nitrite (NaNO2), on the embryonic development of the eyes of albino mice Mus musculus. On the fourteenth and eighteenth day of pregnancy, the stage of organogenesis in these animals. A concentration of 9 g/kg of MSG, a concentration of 110 mg/kg of NaNO2, and the interaction between them used. The results of the study showed the presence of pathological changes to the eyes of the fetuses. The eye on the 14th day of pregnancy, when 9 g/kg of MSG used, there were retinal duplication, increased vascularization in the retina, condensation of some nuclei of the inner nuclear layer and ganglion cells, and necrosis in the vicinity of the lens. When treating with NaNO2 110 mg/kg, there was an irregularity in the lens, corneal distortion, hyperplasia of the retinal nerve tissue. When the two materials overlapped, the corneal tissue necrosis, the lens fiber, and the inner plexiform layer were observed. On the 18th day of pregnancy, when treated with MSG 9g/kg, the most significant overall and striking damage was retinal duplication and optic nerve necrosis. When treated with NaNO2 110 mg/kg, the corneal stroma and dissociation were seen in the photoreceptor cells. In the case of their overlapping, extensive necrosis and reduction appeared in all layers of the retina. The study concluded that consuming MSG and NaNO2 more than the permissible limit during pregnancy leads to tissue lesions harmful to the eye.
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Background: Diodia sarmentosa leaves have gained application in the local treatment of certain ailments. This study evaluated the effect of ethanol extracts of Diodia sarmentosa leaves on biochemical, antioxidant, and histopathological indices of monosodium glutamate-induced uterine leiomyoma in albino rats. Methods: Twenty-one (21) female adult albino rats were acclimatized for 10 days and then classified into three treatment groups, each containing seven rats. Group 1 was the normal control (NC) without any induction, Group 2 was the positive control (PC) and was induced with 200 mg/kg body weight of monosodium glutamate (MSG) without treatment, and Group 3 was the treated group (TG), induced with 200 mg/kg body weight of MSG, then treated with 400 mg/kg body weight of ethanol extract of Diodia sarmentosa leaves for 30 days. Results: The results of the study showed an impaired antioxidant system in the positive control (untreated group). Some biochemical parameters were also altered in the positive control, mostly revealing a relationship between uterine leiomyoma and renal impairment, or kidney damage. Treatment with ethanol extracts of Diodia sarmentosa leaves significantly (P < 0.05) improved the altered biochemical and antioxidant parameters. These findings were also supported by a histopathology result, which revealed the extent of tumors in the affected tissues. Conclusion: The ethanol extract of Diodia sarmentosa (Sw) leaves mitigated oxidative stress and improved the impaired antioxidant system caused by uterine leiomyoma induction. Key words: Diodia sarmentosa, uterine leiomyoma, antioxidant, histopathology
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Background With the advent of food additives centuries ago, the human race has found ways to improve and maintain the safety of utility, augment the taste, color, texture, nutritional value, and appearance of the food. Since the 19th century, when the science behind food spoilage was discerned, the use of food additives in food preservation has been increasing worldwide and at a fast pace to get along with modern lifestyles. Although food additives are thought to be used to benefit the food market, some of them are found to be associated with several health issues at an alarming rate. Studies are still going on regarding the mechanisms by which food additives affect public health. Therefore, an attempt has been made to find out the remedies by exploiting technologies that may convey new properties of food additives that can only enhance the quality of food without having any systemic side effects. Thus, this review focuses on the applications of nanotechnology in the production of nano-food additives and evaluates its success regarding reduction in the health-related hazards collaterally maintaining the food nutrient value. Methodology Ahorough literature study was performed using scientific databases like PubMed, Science Direct, Scopus, Web of Science for determining the design of the study, and each article was checked for citation and referred to formulate the present review article. Conclusion Nanotechnology can be applied in the food processing industry to control the unregulated use of food additives and to intervene in the biochemical mechanisms at a cellular and physiological level for the ensuring safety of food products. The prospective of nano-additive of chemical origin could be useful to reduce risks of hazards related to human health that are caused majorly due to the invasion of food contaminants (either intentional or non-intentional) into food, though this area still needs scientific validation. Therefore, this review provides comprehensive knowledge on different facets of food contaminants and also serves as a platform of ideas for encountering health risk problems about the design of improved versions of nano-additives.
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Monosodium Glutamate (MSG) is one of the world's most widely used food additives. Its toxic effects have been shown in numerous animal studies, however in most of them, the method of administration and the doses were not similar to human MSG intake. In this paper we review animal and human studies in which MSG effects on central nervous system, adipose tissue and liver, reproductive organs and other systems have been shown and we discuss their implications for human MSG intake.
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Animal studies and one large cross-sectional study of 752 healthy Chinese men and women suggest that monosodium glutamate (MSG) may be associated with overweight/obesity, and these findings raise public concern over the use of MSG as a flavour enhancer in many commercial foods. The aim of this analysis was to investigate a possible association between MSG intake and obesity, and determine whether a greater MSG intake is associated with a clinically significant weight gain over 5 years. Data from 1282 Chinese men and women who participated in the Jiangsu Nutrition Study were analysed. In the present study, MSG intake and body weight were quantitatively assessed in 2002 and followed up in 2007. MSG intake was not associated with significant weight gain after adjusting for age, sex, multiple lifestyle factors and energy intake. When total glutamate intake was added to the model, an inverse association between MSG intake and 5 % weight gain was found (P = 0.028), but when the model was adjusted for either rice intake or food patterns, this association was abolished. These findings indicate that when other food items or dietary patterns are accounted for, no association exists between MSG intake and weight gain.
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Monosodium glutamate (MSG) has a long history of use in foods as a flavor enhancer. In the United States, the Food and Drug Administration has classified MSG as generally recognized as safe (GRAS). Nevertheless, there is an ongoing debate exists concerning whether MSG causes any of the alleged reactions. A complex of symptoms after ingestion of a Chinese meal was first described in 1968. MSG was suggested to trigger these symptoms, which were referred to collectively as Chinese Restaurant Syndrome. Numerous reports, most of them anecdotal, were published after the original observation. Since then, clinical studies have been performed by many groups, with varying degrees of rigor in experimental design ranging from uncontrolled open challenges to double-blind, placebo controlled (DBPC) studies. Challenges in subjects who reported adverse reactions to MSG have included relatively few subjects and have failed to show significant reactions to MSG. Results of surveys and of clinical challenges with MSG in the general population reveal no evidence of untoward effects. We recently conducted a multicenter DBPC challenge study in 130 subjects (the largest to date) to analyze the response of subjects who report symptoms from ingesting MSG. The results suggest that large doses of MSG given without food may elicit more symptoms than a placebo in individuals who believe that they react adversely to MSG. However, the frequency of the responses was low and the responses reported were inconsistent and were not reproducible. The responses were not observed when MSG was given with food.
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In 1907 Kikunae Ikeda, a professor at the Tokyo Imperial University, began his research to identify the umami component in kelp. Within a year, he had succeeded in isolating, purifying, and identifying the principal component of umami and quickly obtained a production patent. In 1909 Saburosuke Suzuki, an entrepreneur, and Ikeda began the industrial production of monosodium l-glutamate (MSG). The first industrial production process was an extraction method in which vegetable proteins were treated with hydrochloric acid to disrupt peptide bonds. l-Glutamic acid hydrochloride was then isolated from this material and purified as MSG. Initial production of MSG was limited because of the technical drawbacks of this method. Better methods did not emerge until the 1950s. One of these was direct chemical synthesis, which was used from 1962 to 1973. In this procedure, acrylonitrile was the starting material, and optical resolution of dl-glutamic acid was achieved by preferential crystallization. In 1956 a direct fermentation method to produce glutamate was introduced. The advantages of the fermentation method (eg, reduction of production costs and environmental load) were large enough to cause all glutamate manufacturers to shift to fermentation. Today, total world production of MSG by fermentation is estimated to be 2 million tons/y (2 billion kg/y). However, future production growth will likely require further innovation.
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In 1908 Kikunae Ikeda identified the unique taste component of konbu (kelp) as the salt of glutamic acid and coined the term umami to describe this taste. After Ikeda's discovery, other umami taste substances, such as inosinate and guanylate, were identified. Over the past several decades, the properties of these umami substances have been characterized. Recently, umami has been shown to be the fifth basic taste, in addition to sweet, sour, salty, and bitter. Am J Clin Nutr 2009;90(suppl):719S-22S.
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This is a review of the taste of umami substances, and some related findings. The data demonstrate that, though the taste of the common umami substances such as MSG and IMP is mainly caused by their anions, the effects of their cations, such as Na, should not be ignored. The effects of cations approach the taste thresholds of umami substances. Although the taste threshold of MSG was slightly lower than that of Na, the threshold of IMP was found to be controlled by Na. However, the degree of saltiness was less than 10% above the threshold of the equivalent weight of NaCl. It was also found that the taste of IMP was probably caused by glutamic acid in saliva, since IMP itself has no umami taste. That is, IMP enhances the umami taste of MSG. Finally, comparison of umami sensitivity of Japanese and Americans revealed no difference.
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Lunch intake was followed in 31 matched pairs of hospitalized diabetic patients over four consecutive days. Pairs of patients were matched for type and duration of diabetes, gender, age and body mass index. Lunches were composed of appetizer, meat, vegetables, starch, cheese, bread and dessert; water, coffee, tea and lemon were available. One patient per pair was randomly ascribed to the experimental group and was served vegetable and starch dishes added with 0.6% monosodium glutamate (MSG). Lunch intake was measured by weighing amounts served and left-overs. Patients in the experimental group ingested more starch food than their matched controls, and less lemon juice and yogurt. However, the total energy load at lunch was not different between groups. This effect on meal time food selection replicates earlier observations made on elderly persons. It is suggested that manipulating palatability of various foods within a meal, and especially by using MSG, is an efficient way to affect food selection in the meal, without inducing hyperphagia.
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In this study we describe the most relevant morphological features of the microglial reaction that takes place in the arcuate nucleus (AN) after neurotoxic injury induced by a single subcutaneous injection of monosodium glutamate (MSG) in neonatal rats. The time course of the reaction was evaluated by lectinhistochemistry. Microglial/macrophagic cells were labelled with the lectin obtained from Lycopersicon esculentum and with B4 isolectin from Griffonia simplicifolia. The microglial response was also studied by ultrastructural observations. The histochemical study revealed the presence of few reactive microglial cells at 6 h post-injection. These cells were intensely stained and had a globular morphology but contained no neuronal debris inside them when observed under the electron microscope. At 12 h post-injection, the number of microglial cells had increased and, at the same time, intense phagocytic activity was observed ultrastructurally. The microglial reaction peaked at 24 and 36 h post-injection, when the number of microglial/macrophagic cells was maximum, although the ultrastructural observations showed that at 36 h the amount of debris ingested by macrophages was decreased with respect to animals sacrificed at 24 h. Finally, at 4 days after neurotoxic injection the number and morphology of microglial cells were similar to those observed in the control rats. The ultrastructural study also revealed the existence of microglial cell mitosis in the territory of the AN together with a strong increase in the number of supraependymal cells resembling macrophages in the third ventricle during the lesion. Our data demonstrate that activated microglial cells initially extend throughout the damaged territory, but from 24-36 h onwards they are especially patent in the ventrolateral portions of the AN.