User:Tyingmyshiu/sandbox

Taste receptors
Most taste buds on the tongue and other regions of the mouth can detect umami taste, irrespective of their location. The tongue map in which different tastes are distributed in different regions of the tongue is a common misconception. Biochemical studies have identified the taste receptors responsible for the sense of umami as modified forms of mGluR4, mGluR1, and taste receptor type 1 (T1R1 + T1R3), all of which have been found in all regions of the tongue bearing taste buds. These receptors are also found in some regions of the duodenum. A 2009 review corroborated the acceptance of these receptors, stating, "Recent molecular biological studies have now identified strong candidates for umami receptors, including the heterodimer T1R1/T1R3, and truncated type 1 and 4 metabotropic glutamate receptors missing most of the N-terminal extracellular domain (taste-mGluR4 and truncated-mGluR1) and brain-mGluR4."

Receptors mGluR1 and mGluR4 are specific to glutamate whereas T1R1 + T1R3 are responsible for the synergism already described by Akira Kuninaka in 1957. However, the specific role of each type of receptor in taste bud cells remains unclear. They are G protein-coupled receptors (GPCRs) with similar signaling molecules that include G proteins beta-gamma, PLCB2 and PI3-mediated release of calcium (Ca2+) from intracellular stores. Calcium activates a so-called transient-receptor-potential cation channel TRPM5 that leads to membrane depolarization and the consequent release of ATP and secretion of neurotransmitters including serotonin.

Cells responding to umami taste stimuli do not possess typical synapses, but ATP conveys taste signals to gustatory nerves and in turn to the brain that interprets and identifies the taste quality via the gut-brain axis.

Affects on Health
Umami is seen as a possible way for humans to adjust their caloric intakes by using the benefits of umami satiation and low sodium to eat healthier. It is also seen as a way to regulate appetite, either by satisfying the palate or satiating it for those who need stimulation. The lack of umami taste could decrease caloric intakes, which could lead to poor health. For those who are older, aging, or sick, adjusting the umami levels in food can help to increase salivation due to the gustatory-salivary reflex. This increases the ability to dissolve the components of food, which increases the appeal of the food. This helps those who are struggling to eat have a stronger appetite through the enjoyment of their food. However, constant umami stimulation could lead to the deactivation of umami taste perception. The satisfying affects of the umami taste could also lead to the overconsumption of food, which could lead to obesity.

In regards to those who are aging, sodium can often be a cause for worry in many foods. Umami allows for a reduced salt content in food, which helps those who suffer from high blood pressure. Without sacrificing the taste of food, salt can be reduced for those who need it. Currently, this is not a widespread tactic for food, as most elderly in nursing homes have regulated salt intakes while their glutamate intakes do not coincide accurately. In Japan, where umami would arguably be considered the most mainstream, salt intakes of those in nursing homes ranges from (361-1516mg/100g), while glutamate intake ranges from (16-697mg/100g).

Bibliography:


 * Patients were fed umami deficient food, to which they complained of being hungry, which also correlated with weight loss. This lead to poor health in the patients.
 * Umami stimulation increases salivary flow rate because of the gustatory-salivary reflex.
 * Loss of appetite in the elderly is common, as gustatory function diminishes with age.
 * Patients with the loss of umami taste also exhibited poor health.
 * T1R receptors express the umami taste. They are not only found on the tongue, but also in the duodenum.
 * An umami taste test was developed by this group, which could be used to indicate normal and abnormal umami taste sensations.
 * MSG was used to simulate the umami sensation.
 * Improvements were made to the elderly patients umami sensitivity. This also increased the patients appetites, as well as overall health.
 * Umami induces salivation in humans.
 * Constant umami stimulation could cause deactivation of the umami taste.
 * It can also lead to the overconsumption of food, and therefore obesity.
 * Constant umami stimulation could cause deactivation of the umami taste.
 * It can also lead to the overconsumption of food, and therefore obesity.