Monosodium glutamate is a common seasoning in kitchen, which is mainly composed of sodium glutamate. The function of monosodium glutamate is to freshen up, which is widely used in kitchens in China. The monosodium glutamate was invented by the Japanese in 1908, and it was also called "flavor essence" in Japan, so it was quickly introduced to China. Now some people have begun to replace monosodium glutamate with chicken essence. Some people think that chicken essence is more nutritious and delicious than monosodium glutamate. The older generation will tell us that monosodium glutamate should not be eaten too much, and excessive consumption will have side effects and some harm. The harm of excessive consumption of monosodium glutamate is mainly composed of sodium glutamate. Besides being a good seasoning assistant, monosodium glutamate can decompose glutamic acid during digestion, which can be converted into an inhibitory neurotransmitter by enzyme catalysis in brain tissue. When monosodium glutamate is consumed too much, this inhibitory neurotransmitter will make various nerve functions in the human body in an inhibitory state, resulting in a series of symptoms such as dizziness, headache, drowsiness and muscle spasm. Some people will be anxious and flustered; Some people with sensitive physique may even feel sore bones and weak muscles. In addition, excessive inhibitory neurotransmitters will also inhibit the secretion of thyroid-stimulating hormone from the hypothalamus of human body, which will hinder the development of bones, especially for children. When the consumption of monosodium glutamate exceeds the metabolic capacity of the body, it will also lead to an increase in the content of glutamic acid in the blood, limiting the use of essential minerals such as calcium, magnesium and copper. In particular, glutamic acid can combine with zinc in blood, and the zinc glutamate that cannot be used is excreted, resulting in zinc deficiency in human body. Zinc is an important nutrient for infants' physical and intellectual development. Therefore, infants and lactating mothers should fast or eat less monosodium glutamate. In addition, Japanese researchers believe that long-term excessive consumption of monosodium glutamate may lead to thinning of retina, decreased vision and even blindness. A large amount of glutamic acid slows down the heart operation, increases the contraction range of the heart, and compresses the coronary vessels. A large amount of glutamic acid will stop the heart. Eating too much monosodium glutamate will damage your vision. Researchers at Guangqi University in Japan found that feeding rats with a strong flavor diet will make their retinas thinner and increase the chances of vision damage. After feeding three groups of rats with glutamate food for six months, the researchers found that the retina of rats with high concentration of glutamate food became thinner by 75%, which led to the decrease of vision. However, the visual impairment of rats in the middle concentration group was less. Glutamate enters the body mainly concentrated in vitreous fluid of eyeball, which destroys retinal cells, reduces the impulse signal of optic nerve and makes it blind. HIROSHI, a Japanese expert, announced that the concentration in high glutamic acid food was 20%, and he was not sure what the real concentration was. Glaucoma with normal intraocular pressure in Asia may be related to high glutamate food. The accumulation of glutamate for many years can explain why glaucoma with normal intraocular pressure is more common in the elderly. It used to be thought that monosodium glutamate was harmless and glutamic acid was harmless to people, but now it seems that it should be corrected.