People over the age of 60 are particularly sensitive to sodium intake, so the elderly and people suffering from diseases such as hypertension, kidney disease and edema should especially eat less monosodium glutamate. 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. The harm of monosodium glutamate, is it safe? Is monosodium glutamate harmful to human body? Is monosodium glutamate safe as seasoning? This is the question that the citizens are most concerned about and want to know the answer in order to feel at ease. The answer should be: I don't know at present The harm, "harmfulness" and "safety" of monosodium glutamate are not simple, black and white things. "Eating too much will kill people", even fresh water can be fatal if poured into the stomach in large quantities. Eating too much sugar, salt and oil is also very harmful to health. In fact, most people in Hong Kong do eat too much sugar, salt and oil, causing various serious diseases, such as high blood pressure and heart disease. In short, taking too much food is harmful and unsafe. The problem of monosodium glutamate is particularly complicated, because it is originally a very "natural" substance. The manufacturer of monosodium glutamate points out the following facts, which prove that monosodium glutamate can't be harmful to human body: monosodium glutamate is a natural ingredient in food, and almost all foods containing protein (including human milk) contain monosodium glutamate. Glutamate is continuously produced in the human body, and its composition is exactly the same as monosodium glutamate. The amount of monosodium glutamate used in cooking on weekdays is less than that already in the body and absorbed from other foods. However, things are not divorced from reality, and many people do have long-term problems after eating food containing monosodium glutamate. In addition to psychological effects, one explanation is that some people are sensitive to the sudden increase of monosodium glutamate. Anyone who eats a meal containing a lot of monosodium glutamate feels uncomfortable and has the so-called "monosodium glutamate symptoms". At present, scientific research still can't find a definite reason to explain why those symptoms (see above) are caused. Harm of monosodium glutamate: On the other hand, apart from the short-term discomfort of "monosodium glutamate symptoms", science has not yet confirmed that monosodium glutamate has long-term and serious harm to human body. It is as difficult to prove that a substance will inevitably cause a disease as it is to prove that a substance is harmless to people, and it takes a lot of time and research. So far, it has not been proved that monosodium glutamate is harmful, but it does not mean that it is harmless.