5 Basic Tastes

Umami taste

Sweet(Sugar, Chocolate, etc.)

The history of “umami taste” started in 1908. Professor Kikunae Ikeda of the School of Science at Tokyo
Imperial University (currently the School of Science at Tokyo University) was inspired from the words ofProfessor Hiizu Miyake, the dean of the School of Medicine at Tokyo Imperial University, “good taste
promotes digestion.” Professor Ikeda discovered that L-glutamate in konbu (sea tangle) extract (soupSalty

U mami(Salt, etc.)(Soup Stock of Konbuand Bonito etc.)

stock of sea tangle) had a characteristically good taste, which he named “umami taste.” This was stated in
his scientiﬁc paper in the “Journal of The Tokyo Chemical Society” published in 1909. Later, the Society for
Research on Umami Taste was established in 1982 and proposed to use “umami” as a scientiﬁc term

Sour

Bitter(Vinegar, Lemon, etc.) (Coffee, Bitter Gourd, etc.)

because an English term did not exist.
Since the 1990s, umami has been gaining attention as one of the ﬁve basic tastes (sweet, bitter, salty, sourand umami taste).

Brain

New applications of umami substances

BrainGut axis

Umami substances not only add umami taste to foods but also increase their ﬂavor andEsophagus

thereby improve the appetite. Recent studies suggest that these substances play animportant role in the selection, ingestion, digestion/absorption and metabolism of foods

Liverthat are essential for life. Therefore, umami substances are expected to improve theStomach
Pancreas

quality of life (QOL) for people around the world and are assumed to have various

Small Intestine
Large Intestine

applications.

Mechanisms of detecting umami substances in the digestive tract
Amino acids are known to induce visceral sensations in the stomach and intestine via activation of the vagus nerve. Recent studies in rats indicate that, among the 20amino acids that composes proteins, the gastric vagal aﬀerent nerves speciﬁcally respond to glutamate＊1 . Signals are transmitted from the gastric vagal aﬀerents to theinsular cortex, limbic system, and hypothalamus that regulates food intake, digestion/absorption and metabolism. Thus, an umami taste not only aﬀects food intake butalso digestion. The mechanism by which the brain recognizes this taste and the eﬀective use of substances with an umami taste as a trigger for digestion are being
studied worldwide.
＊1 Reference: Uneyama H, Niijima A, SanGabriel A, et al: Luminal amino acid sensing in the rat gastric mucosa. Am J Physiol
Gastrointest Liver Physiol 291: 1163-1170, 2006

StomachThe vagus nerve contains sensory ﬁbers that transmit information on food in the stomach and small intestine

Vagus Nerve

to the brain. Information on glutamate intake perceived at the surface of the digestive tract is transmitted tothe brain via this nerve.

Gastric Mucosa

With the use of functional MRI, information on the presence of glutamate in the digestive tract is transmitted to the nucleus in the insular cortex, as
well as to the hippocampus, amygdala and hypothalamus, leading to regulation of the appetite, digestion/absorption and metabolism.

Center of memory
Center of emotion

Hippocampus

Amygdala

Dorsomedial nucleus
Lateral hypothalamic area

Insular cortex

Center of the autonomic nervous system

Input of taste and visceral sensation

Umami substances promote digestion
In the 1990s, the Russian Academy of Sciences published a number of reports on the digestion-enhancing eﬀects of substances with an umami taste ＊2 .
When substances with an umami taste (including glutamate) were added to dog food, gastric secretion was promoted. Further, when monosodium
glutamate was added to the food of patients with chronic atrophic gastritis and impaired digestive function, gastric secretion was improved. Recent studies
in human have suggested the possibility that glutamate modulates the transit of food from the stomach to the intestine, in proportion to its nutritional
value ingested and thereby increases the eﬃciency of digestion.
＊2 Reference: Vasilevskaia LS, Rymshina MV, Shlygin GK.. Eﬀect of glutamate and combined with inosine monophosphate on gastric secretion. Vopr. Pitan. 1993; (3): 29-33.

(glutamate+nucleotide)
Gastricjuice

(mL)
50

Brain

Vagus Nerve

Total gastric juice volume

Meat+Umami substances

Meat + Umami substances

40(glutamate+nucleotide)
30
20

Meat
1001234Time after eating

56 ( Hours )