Glutamate or monosodium glutamate (MSG) is the sodium salt of glutamic acid. It activates specific areas of the taste buds and is therefore often used as a flavor-enhancing additive in foods.
Table of contents
- What is glutamate?
- How does glutamate work?
- Other functions of glutamate
- Paradox glutamate level
- Important co-factors
What is glutamate?
Glutamate, also known as monosodium glutamate (MSG), is the sodium salt of glutamic acid. sodium salt of glutamic acida non-essential amino acid. High levels of MSG are naturally found in a number of food sources - including seaweed, soy sauce, parmesan cheese, tomatoes and breast milk.
The uniquely savory taste associated with these foods is called "umami," which is now referred to as the fifth taste.
Interestingly, glutamic acid itself has no umami flavor, but glutatmat activates glutamate receptors in the taste buds. These transmit signals to different regions of the brain and cause the characteristic taste.
The US Food and Drug Administration (FDA) has classified MSG as "generally recognized as safe."
In 1907, scientist Kikunae Ikeda, a professor at the University of Tokyo in Japan, was the first to extract MSG from seaweed. Nowadays, MSG is produced by the fermentation of carbohydrates. The process can be compared to the production of yogurt and wine.
Nowadays, manufacturers are required to list MSG as a component. However, ingredients such as hydrolyzed vegetable protein, autolyzed yeast, soy extract, and protein isolate also contain naturally occurring MSG.
How does glutamate work?
Glutamate is the most important excitatory neurotransmitter in the brain. The stomach and intestinal lining is rich in glutamate receptors. MSG and other forms of glutamate are absorbed by interacting with these receptors. Once in the gut, glutamate is either broken down as fuel or incorporated into other molecules.
It is believed that glutamate supplied through the diet is unable to cross the blood-brain barrier, suggesting that glutamate found in the brain is also produced there.
But there is evidence from studies in mice that the blood-brain barrier in newborns is immature and that some glutamate can get into the brain. High levels of glutamate injected into newborn mice caused significant brain damage. However, there is no evidence of brain damage in humans due to glutamate in the diet.
According to current knowledge, glutamate is essential for the transmission of sensory perceptions, movement control, but also for learning and memory.
Further functions of glutamate
In Alzheimer's patients, both the release and the reuptake of glutamate is impaired. The latter is handled by special transport systems on the brain cells and is particularly important because too much glutamate can destroy the neurons. This so-called exotoxicity probably contributes to the death of neurons after a stroke. Glutamate also seems to play a role in epileptic seizures. In addition, some psychoactive drugs also exert their intoxicating effects via the glutamate receptor.
In contrast to glutamate, GABA is an inhibitory neurotransmitter in the brain. When it docks at the receptor, it decreases the excitability of neurons. You could say that GABA and glutamate are opposites.
Paradox glutamate level
But what about "Chinese restaurant syndrome"? The controversy surrounding the use of glutamate in food - mostly Chinese - continues.
Glutamate consumption has been linked to itching, hyperactivity, headaches, and swelling of the tongue and throat under Chinese restaurant syndrome.
Most studies fail to establish a link between glutamate consumption and physiological symptoms. However, some clinical reports show an association.
Therefore, the question of whether glutamate is the cause of adverse food reactions or whether there is another culprit (especially with today's highly processed foods) remains open.
Vitamin B6 (pyridoxine) is necessary for the biosynthesis of several neurotransmitters. Its concentration in the brain is usually about 100-fold higher than in the blood. The active coenzyme is the phosphorylated derivative pyridoxal phosphate. This coenzyme is involved in glutamate and glutamine metabolism.
Glutamate is primarily known for the exciting taste of chips, Asian food, Parmesan cheese, etc. In the brain, it supports important cognitive functions such as memory. In Alzheimer's patients, both the release and reuptake of glutamate is impaired. Elevated glutamic acid levels have been observed in patients with type 1 diabetes. Elevated glutamic acid levels damage both neurons and beta cells. It is believed that glutamate levels in the brain cannot be affected by diet.