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Contribution of umami taste substances in human salivation during meal

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The oral gustatory perception during a meal has very important physiological roles such as inducing appetite, smoothing mastication and swallowing, promoting digestion and each nutrient availability. One hundred years ago, L-glutamate was discovered as a new taste substance in Japan. Since then, Japanese taste physiologists have lead the research to establish L-glutamate as the prototype molecule for the fifth basic taste (umami taste), in addition to saltiness, sweetness, bitterness and sourness. Meanwhile, various lines of evidence demonstrated that taste perception is linked to taste stimuli-oral/pharyngeal reflexes. In this review, we focus on the efficacy of L-glutamate for human salivation and discuss the possible application of umami taste simulation to the nutritional management for the elderly due to amelioration of their quality of life (QOL).
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INTRODUCTION
The Oral gustatory perception during a meal ful-
fills very important physiological roles in food selec-
tion, subsequently oral functions such as salivation,
which essential for mastication, and swallowing, and
nutrient availability through pre-ingestive responses
as a cephalic phase. From time immemorial, human
beings have used their sense of taste to identify
which foods are good to eat in order to ensure sur-
vival. Each taste portray a different meaning for
the selection of food. Therefore, in the field of taste
physiology research, each sensation of the five ba-
sic tastes (saltiness, sweetness, sourness, bitterness
and umami taste) are thought to have a physiologi-
cal meaning to ingest and maintain each nutrient
homeostasis. A sweet taste indicates that a foodstuff
contains carbohydrates. Sourness tells us whether
a fruit or a vegetable is ripe. Bitterness warns us of
the presence of poisonous substances, and saltiness
helps us to choose foods that contain sufficient min-
erals, particularly sodium ion. Umami taste indicates
the presence of amino acids, i.e. proteins. We can
distinguish a slight change in each nutrient com-
position among daily meals by perception for soluble
taste materials of foods. Purified carbohydrates or
proteins are generally tasteless due to their high
molecular sizes.
Cephalic-phase responses triggered by sensory
properties of food shape the coordinated response
of an incoming nutrient load and enhance food di-
gestion, nutrient absorption and utilization (1). Par-
ticular attention has focused on the cephalic-phase
of exocrine (gastric and pancreatic juices) and en-
docrine (insulin) secretions because of their cru-
cial roles in regulating food digestion and limiting
postabsorptive hyperglycemia (2). Umami as well
as sweet taste stimulation evokes an increase of gas-
tric juice section (pepsinogen and gastric acid) and
pancreatic juice secretion in animals (3, 4).
MINI-REVIEW
Contribution of umami taste substances in human sali-
vation during meal
Hisayuki Uneyama, Misako Kawai, Yuki Sekine-Hayakawa, and Kunio Torii
Physiology and Nutrition Group, Institute of Life Sciences, Ajinomoto Co., Inc., Kawasaki, Japan
Abstract : The oral gustatory perception during a meal has very important physiological
roles such as inducing appetite, smoothing mastication and swallowing, promoting di-
gestion and each nutrient availability. One hundred years ago, L- glutamate was discov-
ered as a new taste substance in Japan. Since then, Japanese taste physiologists have lead
the research to establish L-glutamate as the prototype molecule for the fifth basic taste
(umami taste), in addition to saltiness, sweetness, bitterness and sourness. Meanwhile,
various lines of evidence demonstrated that taste perception is linked to taste stimuli -
oral/pharyngeal reflexes. In this review, we focus on the efficacy of L-glutamate for hu-
man salivation and discuss the possible application of umami taste simulation to the nu-
tritional management for the elderly due to amelioration of their quality of life (QOL).
J. Med. Invest. 56 Suppl. : 197-204, December, 2009
Keywords :dietary L-glutamate, umami taste, human salivation, elderly nutrition.
Received for publication November 19, 2009 ; accepted Novem-
ber 26, 2009.
Address correspondence and reprint requests to Kunio Torii,
D.V.M., Ph.D., Physiology and Nutrition Group, Institute of Life
Sciences, Ajinomoto Co., Inc., Suzuki-cho 1 -1, Kawasaki-ku,
Kawasaki 210- 8681, Japan and Fax : +81 -44 -210 -5893.
The Journal of Medical Investigation Vol. 56 Supplement 2009
197
One hundred years ago, the new taste molecule,
umami taste substance (L-glutamate), was discov-
ered in Japan from the extract of dried sea tangle.
Since then, Japanese taste physiologists have lead
the research that establish L-glutamate as the fifth
basic taste (umami) (5). Meanwhile, many lines of
evidence demonstrated that there is a taste stimuli-
oral/pharyngeal reflex with taste perception. Now
we just began to apply the effect of taste stimulation
to improve oral functions, such as salivation, mas-
tication and swallowing. In this paper, we would
like to review recent clinical advancements on be-
tween umami taste sensation and human salivation.
We will discuss the importance of taste stimulation
during a meal to maintain nutrient homeostasis due
to our health, and propose the possible applications
of umami taste substances, particularly L-glutamate
for the nutritional management in the elderly.
UMAMI TASTE SUBSTANCES IN FOODS
Extracts of seaweed (konbu) have been used as
a soup stock for over a thousand years in Japan. In
1908, moved by the desire to improve the nutritional
status of Japanese, Dr. Kikunae Ikeda at the Tokyo
imperial university discovered that salts of the amino
acid L-glutamic acid were the taste -active compo-
nents of the konbu stock, and named this taste the
umami taste (6). He also invented the production
process for the monosodium salt of L- glutamic acid
(monosodium glutamate : MSG), which consisted
on the hydrolysis of wheat gluten with HCl. Aftter
his discovery and invention, MSG became commer-
cially available as an umami seasoning for the first
time in the world. In recent, it was appreciated that
the molecular discovery of umami receptors in the
taste buds established umami taste as one of the
five basic tastes, distinct from the other basic tastes
such as saltiness, bitterness, sourness and sweet-
ness. Even though it was only recently recognized,
many foods and seasonings popular throughout his-
tory have appeared to be naturally high in umami
taste materials. One such flavoring agent used in
ancient Greece and Rome was a pickled fish sauce
called Garum. This condiment dates back 2500
years, making it the oldest recorded umami season-
ing. Various traditional seasonings around the world,
such as soy and oyster sauce, tomato ketchup, nam
plaaandothersaswellasfoodingredientssuchas
tomatoes and cheese have been found to be rich
sources of free glutamate, and L- glutamate in amino
acid form contributes to the deliciousness of foods
(7, 8).
In 1913, Shintaro Kodama, a colleague of Kikunae
Ikeda, examined the components of katsuo-bushi
(dried bonito) and reported that 5-inosinate was
also involved in umami taste (9). Many years later,
during a study of ribonucleotide production through
biochemical degradation of yeast RNA, Dr. Akira
Kuninaka, another Japanese scientist, identified 5-
guanylate to be one more important umami sub-
stance (10). This nucleotide is naturally present in
a soup stock dashistuff and comes from dried
Japanese black mushroom, shiitake.Now,theseL-
glutamate and 5-ribonucleotides are considered
typical umami taste substances (Fig. 1).
The Ministry of Health and Welfare in Japan (the
Ministry of Health, Labor and Welfare) reported a
daily free L-glutamate intake for people over 20
years of over 1.6 g (12). We wanted to know the
real content of free glutamate to evaluate the prac-
tical free glutamate intake through daily meals.
We measured free amino acid contents in a typical
Japanese lunch box as shown in figure 2. Interest-
ingly, the concentration of total free amino acids in
this lunch was about 1,500 mg from which only 450
mg was free glutamate. Obviously, the total daily
ingestion of free L-glutamate has to be divided into
three meals through breakfast, lunch and dinner.
Fig. 1 Discoveryofmajorthreeumamitastesubstances
The amino acid L- glutamate is the major umami taste component
in Konbu (Japanese sea kelp). 5- nucloeotides, 5- inosinate and
5-guanylate, are major umami taste substance in Katsuo-bushi
(dried bonito) and shiitake (dried Japanese mushroom), respec-
tively. Those three umami substances are commercially available
as monosodium L-glutamate (MSG), 5- inosine monophosphate
(IMP) and 5-guanosine monophosphate (GMP). Figure was
quoted from Uneyma & Yamada (11).
H. Uneyama, et al. Umami taste and human salivary secretion.
198
SENSORY PERCEPTION OF UMAMI TASTE
IN THE ELDERLY
The nutritional management of the elderly, due
to the maintenance of their appetite, mastication,
swallowing, food digestion and each nutrient absorp-
tion, is very important to regulate their body nutri-
tional status during their daily meals. Taste is a fun-
damental sensory system because it regulates food
selection, the hedonic and sensory experience of
food, and related metabolism efficiency. At the end
of all meals, these factors help to preserve a good
quality of life in people, especially the elderly. Taste
also regulates fundamental physiological functions
through cephalic phase reflex, such as exocrine (sa-
liva, gastric and pancreatic juices) and endocrine
(gut hormones) activities during meals. Neck can-
cer patients treated with radiation therapy show
sometimes taste dysfunction including umami taste
loss and umami insensitivity. Among the five basic
tastes, perception of umami taste dysfunctions in
patients is the one presents the strongest co - rela-
tionship with appetite loss (14), suggesting that
umami taste is an important taste quality for appe-
tite in humans. Thinking together, umami taste
stimulation is also expected to normalize oral and
gut functions, when some retardation occurs.
There are several reports describing the taste
threshold of MSG in the old people of the Western
world (15, 16), whereas there is little knowledge
rather than them in Eastern one. Thus, we exam-
ined that relationship between umami taste sensitiv-
ity and preference in the Japanese elderly (Fig. 3).
In this study, we used rice gruel as taste medium,
because it is a familiar ingredient for Japanese
elderly who are used to combine gruel with tradi-
tional savory pickles. As a result, the taste thresh-
old for MSG in these old subjects was 0.5% (39
Fig. 2. Amino acid contents in a typical Japanese lunch box.
Amino acids were measured by an amino acid analyzer in hot -water soluble components. Data were quoted from Uneyama (13).
Fig. 3. Umami taste sensitivity and preference of Japanese
elderly
Two - alternative forced choice test was performed using 0.2% NaCl
containing rice gruel as medium in old women (n=39, 84 !
6.1
year-old). The ratio of correct answer (filled circle) means the
ratio of subjects who correctly chose the gruel with MSG as the
stronger taste comparing gruels with and without MSG. For the
calculation of the preference ratio (open triangle), the preference
in subjects that gave the wrong answer in the sensitivity test was
ignored. Asterisks show statistical significance by binomial test
(* : p!
0.05, *** : p!
0.001). Data were modified from Hayakawa
et al. (17).
The Journal of Medical Investigation Vol. 56 Supplement December 2009 199
women, 84.3!
6.1 year -old), higher than those for
the middle-aged adults (40 women, 49.6!
5.6 year-
old) in which was less than 0,063%. Accordingly,
the optimal preferred concentration of MSG in old
Japanese was around 0.5 % showing a bell-shaped
concentration-preference curve (17). Thus, as ob-
served in other gustatory perceptions, the amount
of ingested L-glutamate seems to be self -limiting
by the intensity of umami taste in food.
UMAMI TASTE STIMULATION IMPROVES
SALIVA SECRETION IN THE ELDERLY
Saliva has many essential functions as shown in
the figure 4. It is the first digestive juice in the ali-
mentary canal and is secreted in response to food
assisting mastication, swallowing and initiation of
the oral digestion of starch and lipids (18). During
this process, saliva acts as a solvent of taste sub-
stances allowing the sensation of taste substances
in variety of foods. Clinically, the most important
role of saliva is the formation of the food bolus and
maintenance of oral health, including the protection
of teeth and mucosa from infections, maintenance
of the milieu of taste receptors and communication
through speech.
Beyond oral health, considerable evidence now
demonstrates that saliva and its components have
multiple functions in the esophageal and gastric
mucosa. Saliva aids the formation of the bolus ; it
lubricates, protects and cleanses the pharyngeal and
esophageal mucosa. Salivary bicarbonate buffers
esophageal acid in common reflux. Salivary epider-
mal growth factor (EGF) stimulates gastrointestinal
(GI) mucosal proliferation via a direct lumenal ef-
fect in the esophagus and stomach (20). Normal
salivary flow decreases the duration of acid contact
with esophageal mucosa, an important factor in the
development of gastro- esophageal reflex disease
(GERD). For instance, the esophageal mucosal bar-
rier is significantly enhanced by the quantity and
the quality of salivary organic components such as
salivary mucin, nonmucin protein, salivary EGF and
salivary prostaglandin E2(21). If salivary flow is de-
pressed or if the esophago- salivary reflex is lost, a
patient may be predisposed to develop GERD.
Ingestion of palatable foods yields the greatest
pleasures in life in general. In the elderly it is most
important to satisfy their appetite and maintain their
dignity and quality of life (QOL). Since the normal
physiological functions in the elderly are compro-
mised and often take various drugs, their taste sensi-
tivity, salivary secretion, chewing and swallowing,
Fig. 4. Physiological functions of saliva
Saliva has many essential functions regulating appetite, mastication, swallowing, digestion, and maintenance of the gastrointestinal
mucosa. The figure was modified from ref. 19. See the text for details.
H. Uneyama, et al. Umami taste and human salivary secretion.
200
as well as the sanitary condition of the oral cavity,
are often prone to deterioration. The effectiveness
of umami taste se sensation for salivation in humans
was first reported by Dr. Kawamura and colleagues
from Osaka university, Japan (22). Recently, it has
been re-confirmed that a typical umami taste ma-
terial (MSG) at most preferable concentration (0.5%)
induces salivary secretion in the healthy adults (23).
We investigated the temporal pattern of MSG-in-
duced salivation in the healthy adults (Fig. 5). The
time-course of salivation after the gustatory stimu-
lation with umami taste (MSG) was compared with
the effect of sour taste (citric acid) at the same in-
tensity. The reason why we used sourness as a con-
trol taste stimuli is that sourness is often used for
promotion of salivary secretion in hospital for the
oral care. Interestingly, sour taste was a strong sali-
vary inducer but during a short period of time
(within 2 min after taste stimulation in our condi-
tion). In contrast, umami taste sensation induced a
long-lastingsalivarysecretion(morethan10min).
Therefore, the total amount of saliva induced by
umami taste (MSG) stimulation became significantly
larger than the case of sour taste stimulation (24).
As considering the function of saliva in mastication,
swallowing and cleanness of the oral cavity, this
feature of umami taste seems to be important for
normal digestion. The use of umami taste materials
in oral care might be helpful to maintain the oral
mucosal integrity in patients with dry mouth. In-
deed, an effective salivation with umami taste stimu-
lation was observed in the elderly with otherwise
hyposalivation (25). Shiffman reported previously
that the supplementation of foods with MSG im-
proved salivary flow and increased the total amount
of secreted IgA in the elderly (25) (Fig. 6). As
Fig. 6. Effects of umami taste stimulation on the salivary IgA in the elderly.
Secretion rate of sIgA (left), and concentration of sIgA (right) of collected saliva secreted were shown after taking chicken soup with
(black bar) and without (white bar) MSG. Each column and vertical bar indicates mean!
s.e.m., respectively. Data were quoted from
Schiffman et al. (25).
Fig. 5. Effects of umami taste stimulation on human salivation.
After subjects tasted 3 ml of each stimulus solution for 30 sec, then they spat content in their mouth at every 30 sec for 10 min (n =
24). The weight of the content except stimulus solution was regarded as the weight of secreted saliva. Salivary flow per min (left)
and total saliva for 10 min (right) were presented with mean!
s.e.m.. In the graph for salivary flow, same symbol in each time
means that there is no significant difference. Data was modified from Hayakawa et al. (24).
The Journal of Medical Investigation Vol. 56 Supplement December 2009 201
mentioned before, IgA is one of key molecules to
maintain the mucosal environment as a barrier sys-
tem against bacterial contamination in the oral cav-
ity. Thus, umami-fortified meals might contribute
to the oral care management in the elderly.
POSSIBLE CONTRIBUTION OF UMAMI
TASTE SUBSTANCES IN THE ELDERLY
QOL
Recent animal evidence using L- glutamate indi-
cate that dietary free L- glutamate is sensed by the
alimentary tract and helps gastric digestion, nutrient
absorption and utilization via visceral glutamate in-
formation through vagal afferent pathways (26- 29).
Altogether, umami taste substance, especially MSG,
might be used for its properties in gustatory and
visceral perception to improve the management of
nutritional stasus (Fig. 7). We ingest certain amount
of free L-glutamate, which is a residue of peptides
and proteins, every day through our daily meals be-
cause a great variety of foods (vegetables, meats
and traditional seasonings) contain free L- glutamate.
During ingestion, free glutamate is sensed by the
umami taste receptors on the tongue and the umami
sensation to be yielded, which is thought to indicate
protein intake. The specific appetite for proteins
allows maintaining the body protein (L-amino acid)
homeostasis. At the same time, the sensation of
umami taste induces taste reflexes such as salivary
secretion that is required for mastication and swal-
lowing of meals, and the cephalic phase responses
to prepare the gastrointestinal tract for protein di-
gestion. At the same time, saliva keeps the oral hy-
giene after each meal. After swallowing the food bo-
lus, the free glutamate in the bolus is sensed again
by the visceral afferents that innervate the gastro-
intestinal tract. Glutamate-mediated visceral nutri-
ent information might increase the efficiency of pro-
tein digestion, absorption and utility within the body,
by stimulating the gut function. Free glutamate it-
self is consumed in the mucosa as energy during
protein digestion. The visceral sensation through
post-ingestive process is expected to control the
appetite for protein intake and the visceral afferent
inputs to the brain stem can contribute to the main-
tenance of the basal brain activity. The input of pe-
ripheral sensory stimuli plays very important role
for the activation of brain circuits. Old people has
special difficulties to maintain a proper oral and gut
function, which reduces their QOL with diseases
such as anorexia, aphasia, diarrhea, constipation and
memory dysfunction. Umami taste substances have
the potential to improve these conditions in the eld-
erly with some disorders of GI functions. After MSG
fortification trials in hospitalized elderly, some of the
expected outcomes were reconfirmed (improve the
redox status of plasma albumin, immunity and con-
sciousness) (30-32).
Fig. 7. A new hypothesis based on the scientific evidence for the umami taste substance glutamate in nutritional management.
Scientific evidence for contributing the nutritional management for the elderly was summarized. See text for details.
H. Uneyama, et al. Umami taste and human salivary secretion.
202
CONCLUSIONS
The elderly usually suffers from hyposalivation
due to a reduction of sensory perception such as
taste and smell. Compared to other taste stimuli
such as sourness, umami taste induces long - lasting
salivation in humans. Recently, Sato-Kuriwada and
colleagues reported that oral stimulation with MSG
increased salivary flow in minor salivary glands (33).
It is essential to encourage the ingestion of food in
bedridden old people. With the proper nutritional
management the appetite, mastication, and swallow-
ing can improve in this elderly subjects. A better
understanding of the umami taste physiology espe-
cially in taste reflex will help develop new methods
or new treatments for eating-related disorders such
as disgeusia, dysphagia, dry mouth, and anorexia.
ACKNOWLEDGEMENT
The authors thank for Dr. Ana San Gabriel for
helpful assistance to prepare this review.
REFERENCES
1. Giduck SA, Threatte RM, Kare MR : Cephalic
reflexes : their role in digestion and possible
roles in absorption and metabolism. J Nutr
117 : 1191-1196, 1987
2. Louis-Sylvestre J : Preabsomptive insulin re-
lease and hypoglycemia in rats. Am J Physiol
230 : 56-60, 1976
3. Uneyama H, Kropycheva RP, Andreeva YV,
Torii K, Zolotarev VA : Physiological regulation
of the oral umami taste sensation in the rat gas-
tric secretion. Jpn J Taste and Smell Res 15 :
371-374, 2008
4. Ohara I, Otsuka S, Yugari Y : Cephalic phase
response of pancreatic exocrine secretion in
conscious dogs. Am J Physiol 254 : G424-428,
1988
5. Kurihara K : Glutamate : from discovery as a
food flavor to role as a basic taste (umami). Am
J Clin Nutr 90 : 719S- 722S, 2009
6. Ikeda, K : Japanese patent 4805, 1908
7. Giacometti T, Free and bound glutamate in
natural products. In : Filer LJ, Garattini S, Kare
MR, Reynolds AW, Wurtman RJ eds. : Glutamic
acid : advances in biochemistry and physiology.
New York : Raven Press, 1979 : 25-34
8. Kawai M, Uneyama H, Miyano H : Taste- active
components in foods, with concentration on
umami compounds. J Health Sci 55 : 667-673,
2009
9. Kodama S : On a procedure for separating inos-
inic acid. J Tokyo Chem Soc 34 : 751- 757, 1913
10. Kuninaka A : Studies on taste of ribonucleic
acid derivatives. J Agric Chem Soc Jpn 34 : 487 -
492, 1960
11. Uneyama H, Yamada Y : Possible applications
of umami taste to improve eating disorders. J
Health Sci 55 : 699- 700, 2009
12. Yamada T, Ishiwta H, http : //www.ffcr.or.jp/
zaidan/FFCRHOME. nsf/pages/DI-study
13. Uneyama H : Umami : a physiological signifi-
cance of umami taste substances in the dietary
foods. Chromatography 29 (suppl 2) : 15-18,
2008
14. Shi HB, Masuda M, Umezaki T, Kuratomi Y,
Kumamoto Y, Yamamoto T, Komiyama S : Ir-
radiation impairment of umami taste in patients
with head and neck cancer. Auris Nasus Larynx
31 : 401-406, 2004
15. Schiffman SS : Sensory enhancement of foods
for the elderly with monosodium glutamate and
flavors. Food Rev Int 14 : 321- 333, 1998
16. Stevens JC, Bartoshuk, LM, and Cain WS :
Chemical senses and aging : Taste versus smell.
Chem Senses 9 : 167-179, 1984
17. Hayakawa Y, Kawai M, Sakai R, Toyama K,
Kimura Y, Iwakiri N, Uneyama H, Torii K :
Umami sensitivity of elderly females : Com-
parison with middle-aged females. Jpn J Taste
Smell Res 14 : 443-446, 2007
18. Pedersen AM, Bardow A, Jensen SB, Nauntofle
B : Saliva and gastrointestinal functions of taste,
mastication, swallowing and digestion. Oral Dis
8 : 117-129, 2002
19. Amerongen AV, Veerman ECI : Saliva - the de-
fender of the oral cavity. Oral Dis 8 : 12-22,
2002
20. Valdez IH, Fox PC : Interactions of salivary and
gastrointestinal systems. I. The role of saliva
in digestion. Dig Dis 9 : 125- 132, 1991
21. Sarosiek J, McCallum RW : Do salivary organic
components play a protective role in health and
disease of the esophageal mucosa? Digestion
56 (Suppl 1) : 32-37, 1995
22. Horio T, Kawamura Y : Salivary secretion in-
duced by umami taste. Shika Kiso Igakkai
Zasshi 31 : 107- 111, 1989
23. Hodson, N, Linden R: The effect of monosodium
The Journal of Medical Investigation Vol. 56 Supplement December 2009 203
glutamate on parotid salivary flow in compari-
son to the response to representatives of the
other four basic tastes. Physiol Behav 89 : 711 -
717, 2006
24. Hayakawa Y, Kawai M, Torii K, Uneyama H :
The effect of umami taste on saliva secretion.
Jpn J Taste Smell Res 15 : 367-370, 2008
25. Schiffman S, Miletic I : Effect of taste and smell
on secretion rate of salivary IgA in elderly and
young persons. J Nutr Health Aging 3 : 158-
164, 1999
26. Uneyama H, Niijima A, San Gabriel A, Torii
K : Luminal amino acid sensing in the rat gas-
tric mucosa. Am J Physiol 291 : G1163-G1170,
2006
27. Uneyama H., San Gabriel A., Kawai M., Tomoe
M., Torii K : Physiological role of dietary free
glutamate in the protein digestion. Asia Pac J
Clin Nutri 17 : 372- 375, 2008
28. Nakamura E, Torii K, Uneyama H : Physiologi-
cal roles of dietary free glutamate in gastroin-
testinal functions. Biol Pharm Bull 31 : 1841-
1843, 2008
29. Kondoh T, Mallick HN, Torii K : Activation of
the gut-brain axis by dietary glutamate and
physiologic significance in energy homeostasis.
Am J Clin Nutr 90 : 832S- 837S, 2009
30. Toyama K, Tomoe M, Inoue Y, Sanbe A,
Yamamoto S : A possible application of mono-
sodium glutamate to nutritional care for elderly
people. Biol Pharm Bull 31 : 1852- 1854, 2008
31. Tomoe M, Inoue Y, Sanbe A Toyama K,
Yamamoto S, Komatsu T : Clinical trial of glu-
tamate for the improvement of nutrition and
health in the elderly. Ann NY Acad Sci USA
1170 : 82-86, 2009
32. Yamamoto S, Tomoe M, Toyama K, Kawai M,
Uneyama H : Can dietary supplementation of
monosodium glutamate improve the health of
the elderly? Am J Clin Nutr 90 : 844S -849S,
2009
33. Satoh-Kuriwada S, Shoji N, Kawai M, Uneyama
H, Kaneta N, Sasano T : Hyposalivation strongly
influences hypogeusia in the elderly. J Health
Sci 55 : 689-698, 2009
H. Uneyama, et al. Umami taste and human salivary secretion.
204
... Las principales funciones de la saliva son la de digestión, de protección, de defensa y de regulación. Sus múltiples funciones se relacionan con su compleja composición como se observa en la Fig. 2 3 . Figura 2: Funciones fisiológicas de la saliva en relación a sus constituyentes. ...
... Figura 2: Funciones fisiológicas de la saliva en relación a sus constituyentes. Adaptado de: Uneyama et al. 3 Actualmente la sialometría y la sialoquímica representan una alternativa cada vez más útil para el diagnóstico y/o seguimiento de numerosas enfermedades. En este sentido, los biomarcadores se definen como un parámetro objetivo y mensurable, que sirven como indicador de procesos fisiológicos, del progreso de una patología o del control de la respuesta farmacológica a una intervención terapéutica. ...
... Insbesondere bei Tumorpatienten spielen neben Geschmacksstörungen auch Nahrungsmittelaversionen eine große Rolle. Subjektiv wahrgenommene Geschmacksstörungen und Aversionen gegenüber direkt vor der Chemotherapie gegessenen Lebensmitteln werden vor allem in Zusammenhang mit der zytotoxischen Therapie beschrieben [34,[39][40][41]. Geschmacksstörungen und Nahrungsmittelaversionen sind besonders bei Patienten, die an einer Krebserkrankung leiden gefährlich, da sie zu einem deutlichen Appetitverlust mit möglicher konsekutiver Malnutrition und zur Unterhaltung einer bestehenden Tumorkachexie beitragen können [42][43][44] ...
... Such a correlation has never been verified in a study. However, it is known that glutamate has a stimulating effect on appetite and saliva production [41]. When glutamate is elevated in a meal, the craving for salt and sugar is reduced. ...
Thesis
Hintergrund und Ziele: Patienten, die an einer malignen Tumorerkrankung leiden, sind einem hohen Risiko für Mangelernährung und Kachexie ausgesetzt. Dies erhöht wiederum die Morbidität und Mortalität dieser Patientengruppe. Bislang gibt es keine exakten Auslöser einer tumorbedingten Kachexie. Sowohl inflammatorische Prozesse, als auch eine vorhandene Geschmacksstörung (mit konsekutiv geringerer Nahrungsaufnahme) scheinen jedoch eine entscheidende Rolle hierbei zu spielen. Ziel dieser Studie war es Einblicke in die auslösenden Faktoren von Geschmacksstörungen zu gewinnen. Inwiefern beeinflussen der Tumor selbst, inflammatorische Prozesse oder etwa die tumorspezifische Therapie die Entstehung und Aufrechterhaltung von Geschmacksstörungen? Methoden: Zur Erfassung bestehender Geschmacksstörungen wurden Tumorpatienten (n=42), Patienten, welche aufgrund einer akuten inflammatorischen Erkrankung hospitalisiert (n=57) waren und gesunde Kontrollprobanden (n=39) untersucht. Um den Einfluss einer chemotherapeutischen Behandlung zu untersuchen, wurden Tumorpatienten mit und ohne aktuelle Chemotherapie verglichen. Als Leitfaden für die Geschmackstestung wurde die DIN ISO 3972:2011 verwendet. Zur Quantifizierung der Inflammation wurden Laborparameter verwendet. Die statistische Aufarbeitung erfolgte mit Hilfe der Software R. Ergebnisse und Beobachtungen: Tumorpatienten zeigten im Vergleich zu gesunden Probanden signifikant erhöhte Geschmacksschwellen für süße, salzige und würzige (umami) Geschmacksstoffe. Ein signifikanter Unterschied zwischen Patienten mit früherer, wie auch aktueller Chemotherapie und Chemotherapie-naiven Patienten lag nicht vor. Patienten mit akuten inflammatorischen Erkrankungen hatten verglichen mit Gesunden Patienten erhöhte Geschmacksschwellen für umami. Schlussfolgerungen: Es konnte gezeigt werden, dass Tumorpatienten unabhängig davon ob eine chemotherapeutische Vorbehandlung stattgefunden hatte oder nicht an Geschmacksstörungen leiden. Verglichen mit akuten inflammatorischen Erkrankungsbildern, scheint die malignomassoziierte Inflammation einen größeren Einfluss auf die Entstehung von Geschmacksstörungen zu haben. Dementsprechend sollte bereits in frühen Stadien einer Tumorerkrankung ernährungstherapeutische Begleitung erfolgen um Mangelernährungszuständen vorzubeugen, welche durch Geschmacksstörungen ausgelöst wurden.
... Symptoms of hyposalivation may include dry mouth, discomfort, inadequate nutrition resulting from loss of taste, pain, and a decline in dental health (Golež et al., 2021). Umami is shown to stimulate long-lasting saliva secretion, appetite during consumption, postingestive satiety, and overall improved health and weight (Masic & Yeomans, 2014;Uneyama et al., 2009). These benefits are key in the prevention of undernourishment in the elderly since malnutrition decreases health prospects and quality of life. ...
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Understanding taste is key for optimizing the palatability of seaweeds and other non‐animal‐based foods rich in protein. The lingual papillae in the mouth hold taste buds with taste receptors for the five gustatory taste qualities. Each taste bud contains three distinct cell types, of which Type II cells carry various G protein‐coupled receptors that can detect sweet, bitter, or umami tastants, while type III cells detect sour, and likely salty stimuli. Upon ligand binding, receptor‐linked intracellular heterotrimeric G proteins initiate a cascade of downstream events which activate the afferent nerve fibers for taste perception in the brain. The taste of amino acids depends on the hydrophobicity, size, charge, isoelectric point, chirality of the alpha carbon, and the functional groups on their side chains. The principal umami ingredient monosodium l‐glutamate, broadly known as MSG, loses umami taste upon acetylation, esterification, or methylation, but is able to form flat configurations that bind well to the umami taste receptor. Ribonucleotides such as guanosine monophosphate and inosine monophosphate strongly enhance umami taste when l‐glutamate is present. Ribonucleotides bind to the outer section of the venus flytrap domain of the receptor dimer and stabilize the closed conformation. Concentrations of glutamate, aspartate, arginate, and other compounds in food products may enhance saltiness and overall flavor. Umami ingredients may help to reduce the consumption of salts and fats in the general population and increase food consumption in the elderly.
... These publications lead to suggest glutamate also Nutrients 2021, 13, 2921 9 of 11 could protect oral mucosity. Decreased saliva secretion is also a serious problem during CRT, but MSG has contributed to the promotion of saliva secretion during meals [28], which can be expected to improve QOL, such as eating delicious meals. Therefore, dietary supplementation with MSG may not only improve taste-related quality of life but also ameliorate malnutrition and, thereby, reduce mortality with improved QOL in patients with advanced head and neck cancer treated with CRT. ...
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(Background) We investigated the effect of dietary supplementation with monosodium glutamate (MSG) on chemotherapy-induced downregulation of the T1R3 taste receptor subunit expression in the tongue of patients with advanced head and neck cancer. (Methods) Patients undergoing two rounds of chemoradiotherapy were randomly allocated to a control or intervention group (dietary supplementation with MSG at 2.7 g/day during the second round of chemotherapy). The relative expression of T1R3, a subunit of both umami and sweet taste receptors, in the tongue was assessed by quantitative polymerase chain reaction analysis. Dysgeusia was assessed with a visual analog scale and daily energy intake was evaluated. (Results) T1R3 expression levels in the tongue, taste sensitivity, and daily energy intake were significantly reduced after the first round of chemotherapy compared with before treatment. Furthermore, these parameters significantly decreased after the second round of chemotherapy, but the extent of decrease was significantly attenuated in the MSG group compared with the control group. (Conclusions) MSG supplementation suppresses chemotherapy-induced dysgeusia, possibly due to the inhibition of the T1R3-containing taste receptor downregulation in the tongue, thereby increasing energy intake in patients with advanced head and neck cancer.
... Umami taste is thought to drive protein intake, and sensitivity to umami tastants has been implicated in a variety of sensory and health-related outcomes such as salivary secretion [23], taste enhancement [24], increasing appetite and satiety [25,26], reducing fat mass in rats [27], and obesity [12]. Furthermore, previous research has suggested that umami taste sensitivity is related to an increased liking of dietary protein and the nutritional need of protein in high-protein consumers [28]. ...
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Taste is a fundamental mechanism whereby compounds are detected orally, yet it is highly variable among individuals. The variability in taste that is attributable to genetics is not well-characterized despite its potential role in food selection and therefore eating habits that contribute to risk of overweight and obesity. In order to implicate measures of taste function and preference as potentially deterministic factors in adverse eating behaviours that lead to obesity, it must be shown that a relationship exists between genetic variation in taste receptor genes and psychophysical measures of taste in the absence high BMI. The primary objective of this pilot study was to investigate the relationship between single nucleotide polymorphisms (SNPs) in taste receptor genes and three different psychophysical measures of taste in healthy young adults. Sweet, salt, umami, fat, sour, and bitter taste receptor gene SNPs were genotyped in 49 participants (ages 24.6 ± 0.6 years) who completed testing to determine oral detection threshold (DT), suprathreshold sensitivity (ST) and taste preference (PR). A simultaneous association test was conducted between each SNP and the three taste outcomes (DT, ST, and PR). Twelve SNPs were associated with at least one of the three taste outcomes. Associations were observed between SNPs in taste receptor genes and psychophysical measures of sweet, fat, umami, and salt taste. These results suggest that differences in inter-individual psychophysical measures of tastes, namely DT, ST, and PR, may be partially attributed to genetic variation in taste receptor genes. Future studies are warranted to investigate if these findings have consequences for habitual dietary intake of foods that elicit these tastes.
... Its palatable and favorite flavor is a must in almost all Chinese and South-Asian dishes. L-glutamate is the molecule responsible for the umami taste (the 5 th basic taste in addition to saltiness, sweetness, bitterness and sourness (Amira ,et al.,2016).It is added to the food either as a purified monosodium salt or as a component of a mixture of amino acids and small peptides resulting from the acid or enzymatic hydrolysis of proteins (Uneyama,et al., 2009). Study recorded, the consumption MSG has increased all over the world (Beyreuther, et al., 2007).ALA is a specific antioxidant; it can easily quench radicals, has an amphiphilic character, and does not exhibit any serious side effects (Gora, et al., 2011). ...
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This is an Open Access Journal / article distributed under the terms of the Creative Commons Attribution License (CC BY-NC-ND 3.0) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. All rights reserved. Monosodium Glutamate is one of the most world's most widely used food additives. Its toxic effect have been shown in numerous animal studies, in which study MSG effects on cardiovascular system, therefore, This study was aimed to investigate the adverse effect of Mono sodium glutamate (MSG) on the ECG alteration and damage large blood vessels. Thirty two male rabbits was divided equally and randomly into four groups as following. Control group in which rabbits where fed with normal diet without supplementation, second group was gived MSG orally (8mg/kg.BW), While animals of third group were given ALA orally (60mg/kg.BW) while animal in fourth group were given orally (MSG 8mg/kg.bw and ALA 60mg/kg.bw), all treatment are extended to 10 weeks. there is a significant increase (p<0.05) in peroxynitrate (ONOO) andmalondialdehyde(MDA) a significant decrease (p<0.05) in glutathione(GSH) in second group in comparison with control group and group received ALA.
... Its palatable and favorite flavor is a must in almost all Chinese and South-Asian dishes. L-glutamate is the molecule responsible for the umami taste (the 5 th basic taste in addition to saltiness, sweetness, bitterness and sourness (Amira ,et al.,2016).It is added to the food either as a purified monosodium salt or as a component of a mixture of amino acids and small peptides resulting from the acid or enzymatic hydrolysis of proteins (Uneyama,et al., 2009). Study recorded, the consumption MSG has increased all over the world (Beyreuther, et al., 2007).ALA is a specific antioxidant; it can easily quench radicals, has an amphiphilic character, and does not exhibit any serious side effects (Gora, et al., 2011). ...
Article
Full-text available
Monosodium Glutamate is one of the most world’s most widely used food additives. Its toxic effect have been shown in numerous animal studies, in which study MSG effects on cardiovascular system, therefore, This study was aimed to investigate the adverse effect of Mono sodium glutamate (MSG) on the ECG alteration and damage large blood vessels . Thirty two male rabbits was divided equally and randomly into four groups as following. Control group in which rabbits where fed with normal diet without supplementation, second group was gived MSG orally (8mg/kg.BW), While animals of third group were given ALA orally (60mg/kg.BW) while animal in fourth group were given orally (MSG 8mg/kg.bw and ALA 60mg/kg.bw), all treatment are extended to 10 weeks. there is a significant increase (p<0.05) in peroxynitrate (ONOO) andmalondialdehyde(MDA) a significant decrease ( p<0.05) in glutathione(GSH) in second group in comparison with control group and group received ALA.
... In contrast to the complications associated with a lack of oral intake, gustatory stimulation is linked to a range of potential benefits for persons with dysphagia and xerostomia. First, the introduction of virtually any substance into the mouth is known to increase salivary flow [15][16][17][18]. For some patients with dysphagia who are unable to manage the increased secretions safely, a higher risk of aspiration and related complications could result. ...
Article
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The full text of this paper is viewable at https://digitalcommons.unl.edu/specedfacpub/175/ and also at https://rdcu.be/Oigp ____________________ Non-food gustatory stimulation has multiple potential therapeutic benefits for people with dysphagia and xerostomia. This study examined palatability and saliva flow associated with dissolvable flavored films. Taste strips with real-food flavors dissolved on the tongues of 21 persons with dysphagia and/or xerostomia and 21 healthy age- and sex-matched adults while sublingual gauze pads absorbed saliva over randomized 3-min trials. Participants rated taste enjoyment for each trial on a hedonic general labeled magnitude scale. Flavored strips elicited more saliva than baseline for both groups, and production was higher for controls than patients (M = 2.386 and 1.091 g, respectively; p = 0.036). Main effects of flavor were observed for saliva production (p = 0.002) and hedonics (p < 0.001). Hedonic ratings and saliva production were weakly correlated (r = 0.293, p < 0.001). Results support dissolvable taste strips as a tool for providing low-risk taste stimulation in dysphagia and for eliciting an increase in saliva flow that may provide temporary relief from dry mouth symptoms. The preferred flavors were, on average, also the ones that elicited greater saliva production. Taste strips have the potential to be beneficial for swallowing-related neural activity, timing, and safety in dysphagia. Further, they may ameliorate complications of xerostomia.
Article
Umami intensity promotes food flavor blending and food choice, while a universal quantification procedure is still lacking. To evaluate perceived umami intensity (PUI) in seven categories of foods, modified two-alternative forced choice (2-AFC) method with monosodium glutamate as reference was applied. Meanwhile, we explored whether equivalent umami concentration (EUC) by chemical analysis and electronic tongue (E-tongue) are applicable in PUI quantification. The results indicated that EUC was appropriate in quantifying PUI of samples from meat, dairy, vegetable and mushroom groups (r = 1.00, p < 0.05). Moreover, models with a good prediction capacity for PUI and EUC (R² > 0.99) were established in separated food categories by back propagation neural networks, where E-tongue data were set as input. This study explored the effectiveness of the three methods in evaluating the PUIs of various foods, which provides multiple choices for the food industry.
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A century ago, an amino acid, L-glutamate (Glu), was found to be the important substance for umami (savory) taste of a Japanese soup stock cooked with sea tangle. Since that time, umami seasoning has been used to make foods palatable all over the world. Chemical analysis proved that Glu had been used for savory seasonings around the world, though its taste had been hidden behind the flavors of fat or herbs. Recently, research has shown that Glu affects the chemical senses not only in the oral cavity but also in the gastrointestinal tract, and it modulates the ingestion, digestion and metabolism of proteins. Umami taste, one of the five basic tastes along with sweet, salty, sour and bitter tastes, derived from Japanese cuisine, might be applicable for the nutritional care of elderly people, who are at risk for protein malnutrition even in developed countries.
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Saliva has multiple essential functions in relation to the digestive process taking place in the upper parts of the gastrointestinal (GI) tract. This paper reviews the role of human saliva and its compositional elements in relation to the GI functions of taste, mastication, bolus formation, enzymatic digestion, and swallowing. The indirect function of saliva in the digestive process that includes maintenance of an intact dentition and mucosa is also reviewed. Finally, pathophysiological considerations of salivary dysfunction in relation to some GI functions are considered.
Article
Aging is sometimes associated with decreased sensitivity to tastants, i.e., hypogeusia. The loss of taste sense induces not only the decreased quality of life (QOL), but also weight loss or health problems in the elderly. In our recent study, whole saliva secretion including minor salivary secretion, was found to be significantly decreased in the elderly with gustatory impairment, while it was normal in all of the elderly with normal taste thresholds, indicating that hyposalivation is closely related to hypogeusia. Moreover, clinical studies have shown that treatment for hyposalivation alleviates hypogeusia, even that due to the side effects of prescribed drugs or the effects of disease, e.g., nervous disorders or endocrine disorders. Thus, salivation is essential for maintenance of the normal taste function. Many medications for relief of dry mouth, primarily parasympathomimetic drugs, have serious adverse effects such as palpitation, sweating, nausea, diarrhea or dizziness, particularly in the elderly. To circumvent this problem, we use glutamate (umami taste) in an attempt to increase salivary secretion and to alleviate hypogeusia. An umami stimulus might be an effective method for the alleviation of hypogeusia through improvement of hyposalivation or dry mouth without side effects in aged patients. Consequently, attempts should be made to remedy hypogeusia by alleviation of hyposalivation so as to maintain and promote the health of the elderly.
Article
Earlier studies have suggested that aging may adversely affect the sense of smell more than the sense of taste. Although both sense modalities lose some absolute (threshold) sensitivity, agerelated losses of suprathreshold magnitude seem to occur commonly in the sense of smell, less commonly in the sense of taste. This apparent difference between taste and smell was put to direct test in the same subjects in the same test session. Young (20–25 years) and two groups of elderly people (65–78 and 80–95 years) estimated the taste intensity of various concentrations of NaCl and the odor intensity of various levels of iso-amyl butyrate, under instruction to make magnitude estimations of both kinds of stimuli on a common scale. Relative to the taste estimates, the old gave lower odor estimates than the young. Also, the 80–95 year group showed, on average, a greater odor deficit than the 65–78 year group. This outcome supports the main hypothesis that as age increases smell deficits present a more serious problem than do taste deficits.
Article
Worldwide, both the number and proportion of elderly persons is increasing dramatically. By 2025, it is predicted that there will be 1.121 billion persons over 60 years of age. Most of these elderly will have sensory losses including impairment of taste and smell perception. Taste and smell losses are serious because they can lead to inadequate dietary intake and impaired nutritional status. Dietary patterns in the elderly can be improved by sensory enhancement of foods using monosodium glutamate (MSG) and/or commercial flavors to compensate for chemosensory losses. Intensification of taste and odor with MSG and flavors can improve food acceptance, increase salivary flow and immunity, and reduce oral complaints.