Adverse Reactions to Monosodium Glutamate (MSG)

Q:  I saw your column about MSG, and I, too, have a reaction to it: I get a very uncomfortable tightening in my chest, am unable to swallow, and I begin to hypersalivate. It usually starts about 5 to 10 minutes after I start eating and can last 5 to 15 minutes depending upon how much I have eaten (or how much MSG I have consumed). I mentioned this to an allergist once and he said that glutamate is a gut transmitter so rather than an allergic response, it may have a direct action on the esophagus. (I interpreted this as esophageal spasm, as, once I tried to drink some water during one of these episodes and couldn't swallow).

It happens primarily after Chinese food (my wife's oyster sauce chicken was where I first noticed the reaction). Another time it occurred after Kentucky Fried Chicken Original recipe, which I thought odd until I came across a book one day that tried to copy various recipes, and the only ingredient they could identify in the "eleven herbs and spices" was MSG. It also occurs with McDonald's McLean deluxe burger, which is made with a seaweed compound that is also a precursor of MSG.

The allergy people said they would do a swallow evaluation with an MSG stimulus, but the experience is so unpleasant, (I feel like I am dying), I have never taken them up on their offer. I basically avoid the above and emphatically request "no MSG" at Chinese restaurants.

A:  You are not alone in suffering from Chinese Restaurant Syndrome. Surveys show that from 6-25% of people will have burning skin sensations, heart palpitations, weakness, numbness, muscle tightening, or lightheadedness. Your difficulty swallowing may indeed be spasm of the esophagus, since one researcher has shown similar effects in guinea pig intestines.

It's good that you've discovered on your own some specific foods to avoid, but you need to know that there is much "hidden" MSG in labeling. I just learned this from a chapter from the "allergy Bible" that Tom Puchner, MD, formerly an Instructor in Allergy at the Medical College of Wisconsin, sent me. As of 1995, the Food and Drug Administration (FDA) has approved labeling for MSG under these terms as well: hydrolyzed vegetable protein, natural flavoring, flavor, hydrolyzed plant protein, and Kombu extract. These terms are technically correct since MSG is produced commercially by hydrolysis of plant and vegetable protein.

The FDA classified MSG "generally as safe" and has set no limitation on its quantity in food. MSG was routinely added to infant formula until the late 1960s when studies were released about MSG toxicity in the nervous system of baby mice. These effects have not been shown in adult animals or humans.

"Dear Doctor" is a compilation of patient questions answered by doctors from the Medical College of Wisconsin.