MSG, or monosodium glutamate, occurs naturally in some foods like tomatoes and cheese. However, its principal purpose nowadays is to enhance food flavor. MSG appeared in 1908 after Japanese researches discovered its use. Since then, the food industry identified it as a useful food additive because the taste remains the same regardless of the quality or freshness of the other ingredients. The FDA declared it safe (GRAS), but they also categorized artificial sweeteners, sugar, salt, etc. as GRAS. The Center for Science in the Public Interest states that not all GRAS foods go through meticulous testing, which is crucial to make known artificial ingredients safe.
Products containing MSG are popular. If you add it to your dishes, you will notice that the food tastes good no matter what. It gives it an umami taste, which is savory and meaty. 
Even if MSG is GRAS, experts argue that it can have several harmful side effects when consumed long term.
Is it Harmful?
MSG comes from glutamic acid, one of the most common amino acids. The problem is that there are some studies which prove that it has dangerous effects on the human body, while others show that we need more research to say it is harmful. In any case, we have some proof that MSG could cause CNS disorders, hepatic damage, obesity, reproductive malfunctions, disruptions in adipose tissue physiology, and cardiorenal syndrome. Nonetheless, we need more studies to prove the link between this food additive and cardiovascular diseases, hypertension, and headaches. 
Sometimes people experience MSG side effects. These symptoms include headache, muscle tightness, weakness, skin flushing, tingling, nausea, etc. These were reported after eating high amounts of Chinese food or products containing MSG.  Apart from this, some people might even have a sensitivity to the additive. Anyone who experienced unpleasant side effects after consuming MSG, should avoid or limit it. Many people say MSG isn't more harmful than any other preservative or food additive. However, bear in mind that it is mainly present in processed foods and low-quality products, which shouldn't be part of your regular diet.
Foods Containing MSG
The FDA demands that companies that produce foods containing added MSG list it in the ingredient panel. When you do your groceries, look for monosodium glutamate or E621. MSG also occurs naturally in hydrolyzed vegetable protein, autolyzed yeast, hydrolyzed yeast, yeast extract, soy extracts, and protein isolate, as well as in tomatoes and cheeses. In these cases, the FDA doesn't demand companies to list it in the ingredient panel.
The fast-food industry is the leading user of MSG. No wonder it tastes so good! You can find it in Chinese food, McDonald's, KFC, and Chick-fil-A. These are just a few examples, but if you go to other fast-food restaurants, their products will most probably have the same ingredients.
Here is a list of other foods that contain MSG:
- Chips and snacks
- Seasoning blends
- Frozen Meals
- Canned soups and soup mixes
- Processed meats
- Condiments (salad dressings, mayonnaise, BBQ sauce, etc.)
- Instant noodle products
In conclusion, anything which takes your taste buds on a trip to Disney Land might contain MSG. Foods that have a savory, meaty taste, even though it's not natural, most probably contain a sort of additive that enhances their flavor.
on March 2, 2020