Recently I felt sick after I visited the Chinese restaurant next door. I have heard that monosodium glutamate is commonly used in Chinese food and could cause allergic reactions. Why is this food additive used?

Monosodium glutamate (MSG) is the sodium salt of glutamic acid. Glutamate is a naturally occurring amino acid that is found in nearly all foods, especially high protein foods such as dairy products, meat and fish and in many vegetables. The human body also produces glutamate and it plays an essential role in normal body functioning.

When MSG is added to foods it produces a flavour similar to the glutamate that occurs naturally in foods. It acts as a flavour enhancer and adds a fifth taste, called “umami”, which is best described as a savoury, broth-like or meaty taste.

In the European Union, MSG is classified as a food additive (E621) and regulations are in place to determine how and when it can be added to foods. Typically, MSG is added to savoury prepared and processed foods such as frozen foods, spice mixes, canned and dry soups, salad dressings and meat or fish-based products. In some countries, it is used as a table-top seasoning.

MSG used to be blamed for “Chinese Restaurant Syndrome” because the first anecdotal report of a reaction was made following the consumption of a Chinese meal. Symptoms reported included burning sensations along the back of the neck, chest tightness, nausea and sweating. However, a double-blind controlled challenge of individuals claiming to suffer from the “syndrome” failed to confirm MSG as the cause. Other studies have found that allergic-type reactions after Asian meals are more often due to other ingredients such as shrimp, peanuts, spices and herbs. If you think you are sensitive to MSG or any other food ingredient, the best advice is to check with your doctor or with a dietitian and read food labels carefully.