Many people are accustomed to using MSG when cooking, but according to a recent survey in Taiwan, about 30% of people have experienced symptoms such as drowsiness and irritability due to excessive MSG intake.
The main component of MSG is sodium glutamate, which can break down into glutamate during digestion. The latter, catalyzed by enzymes in brain tissue, can be converted into an inhibitory neurotransmitter. When excessive MSG is consumed, this inhibitory neurotransmitter can suppress various neural functions in the body, leading to a series of symptoms such as dizziness, headaches, drowsiness, and muscle spasms. Some may also experience irritability and anxiety. People with more sensitive constitutions may even feel bone pain and muscle weakness. Furthermore, excessive inhibitory neurotransmitters can also suppress the secretion of thyrotropin-releasing hormone by the hypothalamus, hindering bone development, with a particularly significant impact on children.
Consuming too much MSG often leads to thirst because MSG contains sodium, and excessive intake can lead to high blood pressure. People over 60 are particularly sensitive to sodium intake, so the elderly and those with conditions such as hypertension, kidney disease, or edema should especially limit their MSG consumption.
When excessive MSG is consumed beyond the body's metabolic capacity, it can also lead to increased levels of glutamate in the blood, limiting the body's utilization of essential minerals such as calcium, magnesium, and copper. In particular, glutamate can bind with zinc in the blood to form glutamate zinc, which cannot be utilized and is excreted, leading to zinc deficiency in the body. Zinc is an important nutrient for the physical and intellectual development of infants and young children. Therefore, infants, young children, and mothers who are breastfeeding should avoid or strictly limit their consumption of MSG. Additionally, Japanese researchers believe that long-term excessive MSG consumption may lead to retinal thinning, decreased vision, and even blindness.
So, how much MSG is appropriate per meal? Researchers suggest that no more than 0.5 milligrams should be used per dish. The severity of MSG's side effects can vary depending on an individual's constitution. Therefore, while enjoying delicious food, everyone should also pay attention to their health.