What is MSG?
First, let's define what we're talking about. Monosodium glutamate, or MSG, is the free form sodium salt of glutamic acid. Glutamic acid naturally occurs in many fermented or aged foods, including soy sauce, fermented bean paste (miso), and cheese. It's also found in asparagus, tomatoes, corn, peas, and even human milk.
Glutamic acid was identified in the year 1866 by Karl Ritthausen, in German chemist. Later, in 1907, Kikunae Ikeda, a researcher at theTokyo Imperial University, identified it in the brown crystals left behind after the evaporation of kombu. These crystals of glutamic acid reproduced a flavor he detected in many foods, especially in seaweed. Professor Ikeda called this flavor umami. He went on to patent a method of mass-producing a crystalline salt of glutamic acid: MSG.
MSG and Chinese Restaurant Syndrome.
The question of MSG's safety began in April, 1968. Robert Ho Man Kwok wrote a letter to the New England Journal of Medicine stating:
“I have experienced a strange syndrome whenever I have eaten out in a Chinese restaurant, especially one that served northern Chinese food. The syndrome, which usually begins 15 to 20 minutes after I have eaten the first dish, lasts for about two hours, without hangover effect. The most prominent symptoms are numbness at the back of the neck, gradually radiating to both arms and the back, general weakness and palpitations...”
In 1969 this syndrome was attributed to the flavor enhancer glutamate, largely due to the widely-cited article "Monosodium L-glutamate: its pharmacology and role in the Chinese Restaurant Syndrome" (CRS)* published in the journal Science, that year. It became known under the names "Chinese food syndrome" and "monosodium glutamate symptom complex."
Symptoms attributed to the Chinese restaurant syndrome are rather common and unspecific. They have included burning sensations, numbness, tingling, feelings of warmth, facial pressure or tightness, chest pain, headache, nausea, rapid heartbeat, bronchospasm in people with asthma,drowsiness, and general weakness.
The Science of MSG Safety
Finding reliable studies on the safety of MSG had been a struggle. As with all things on the net (including this article), lots of people seem to quote lots of other people and then say, “See? This shows I'm right” regarding their position on the safety of MSG. Oddly, people on both sides of the argument quote the same studies as evidence as being for their position, and against the opposing one.
The problem with many of the studies that show MSG is the cause of CRS symptoms, an association has never been demonstrated under rigorously controlled conditions, even in studies with people who were convinced that they were sensitive to the compound. A 2002 study, for example, found that rats fed on diets supplemented with 10% and 20% pure monosodium glutamate suffered retinal degeneration, possibly through glutamate accumulation in the eye. The problem is, these amounts are more than 10 times higher than those used for flavoring or naturally found in foods prepared for human consumption.
The one constant seems to be MSG sensitivity. Some people are sensitive to it, and others aren't. Those that are sensitive should avoid it. Those that are not sensitive, can enjoy it in moderate amounts.
My Take on MSG
After reading doing the research, and reading the hype on both sides, I've decided to throw my hat in with the MSG is generally safe at normal consumption levels crowd. I've never suffered when eating MSG laden food at Chinese restaurants. It's not just Chinese food, though. You're likely to get as much glutamic acid from eating pizza with tomatoes and Parmesan cheese as you are moo goo gai pan.
Does that mean I'm going to rush out and buy a bottle of MSG? No, but not because it isn't safe. I simply don't need to. It's already found in ingredients I commonly use to help flavor foods, such as meat stocks and cheeses. I don't add any ingredient to my foods unless there's a reason. If I don't need the MSG to make things taste good, why buy it?
For more information on MSG, and another foodie's take on the MSG safety issue, I found the following websites to be useful, or at least entertaining:
If MSG is so bad for you, why doesn't everyone in Asia have a headache? - The Guardian
Monosodium glutamate (MSG): Is it harmful? - The Mayo Clinic
Monosodium glutamate: Poison the body to better the taste! - Worldwide Health Center (this is a commercial site, but the posted article was interesting)
Research on MSG – Feingold Association
MSG Myths (video) – Web MD
*Note that CRS, Chinese Restaurant Syndrom, should not be confused with the other kind of CRS that so many of us face as we get older: Can't Remember .... what was I talking about, again?