The "What's That Stuff?" on monosodium glutamate (MSG) by Maureen Rouhi was interesting and informative (C&EN, July 28, page 57). However, I must take exception to devoting one-third of the piece to the views of the Glutamate Association. The impression left with the reader is that MSG presents no risk of any kind and/or that Chinese restaurant syndrome (CRS) has no basis in fact. From my own experience, I find that doubtful.
I have been eating in Chinese restaurants for more than 50 years and have had some very significant episodes of CRS. One episode was so severe that I almost stopped breathing. In reviewing the results of my own experiences, several points are clear: First, not everyone experiences CRS. In my family, my mother and I were sensitive, but my father was not when sharing the same food. Second, not all Chinese restaurants trigger the syndrome. The ones that did were generally the smaller and less expensive ones. My CRS reactions have decreased significantly since the 1970s and have essentially stopped occurring. And third, the one ingredient common to Chinese restaurants and used in large amounts was MSG.
Anecdotal evidence does not make a good medical study and MSG may not be the trigger, but CRS is real, reproducible, and a significant risk factor for some portion of our population.
Grosse Pointe Woods, Mich.
I am writing to take you to task for your article on glutamates. For persons such as myself, life is not as good as it might be, as we have become sensitive to excess free glutamates in our diets. The most frustrating aspect of this is the industry practice of using substances that have been deliberately processed to form or to increase the free glutamate content without informing the public. Thus, we find, by trial and error in many cases, that we cannot eat most industry "prepared" foods without becoming ill and that a potluck meal is often like Russian roulette. (Strangely, my friends and I, who do not routinely use processed foods in our cooking, eat very luscious meals without glutamate-induced illness.)
It is well known among those who have glutamate sensitivity that eating out is difficult and that our choices are very limited even in restaurants that "don't use MSG." This is in part due to Food & Drug Administration loopholes that allow the use of a variety of terms for introduced food additive mixtures that contain substantial proportions of glutamates but that are called something else that restaurant cooks are often unable to decipher the composition of.
This is illustrated by the grocery store bouillon containers that I have recently seen that prominently proclaim "no MSG added." The vast majority of shoppers probably misinterpret what that means, unless they are glutamate sensitive and are fortunate enough to know what makes them ill.
I will match your unbiased Glutamate Association references to the safety and nontoxicity of glutamates with the unbiased references available from the National Organization Mobilized to Stop Glutamate (http://www.nomsg.com). Increased glutamate concentrations in prepared foods may not present a health risk to the majority of the well-nourished American public, but it makes the lives of those who are sensitive to such elevated glutamate levels more challenging than we would like. Even accurate labeling would be a huge help for us (http://www.truthinlabeling.com). I am saddened that you did not consult someone who knows something about glutamate sensitivities before you sang the praises of MSG as promulgated by the Glutamate Association.
Donald F. Gaines
Blue Mounds, Wis.
I enjoyed your article on monosodium glutamate. You probably will receive some letters from individuals who believe there is good evidence for adverse side effects in some sensitive people who consume MSG (despite manufacturers' studies and FDA opinion). The fact is that MSG is chiral and does not consist solely of the sodium salt of l-glutamate, even in the best commercial preparations. The enantiomer d-glutamate exists in commercial preparations at about the 0.2% level and at much higher levels in processed and fermented foods/sauces (sometimes exceeding 30%) [Chirality, 6, 277 (1994)]. Perhaps some studies should be done on the effects of d-glutamate, since it is known that different enantiomers sometimes elicit different biological responses in certain individuals.
Daniel W. Armstrong
Just because a product is labeled as MSG does not mean it is 100% pure MSG. Although MSG itself does not cause harmful health effects, as mentioned in Rouhi's article, some of the inferior products on the market are not sufficiently pure. Having cooked in restaurants for a number of years to finance my college education, I can testify that MSG is definitely not manufactured equally. MSG from certain less expensive sources is a bit yellowish and is clearly visibly less pure to a layman. This type of inferior MSG resulted in more restaurant customers complaining about the ill effects. There exists sufficient commonsense evidence to discount the harmful effects, which I have<br > no doubt are caused by fermentation by-products/impurities. Perhaps attention should be paid to the impurities.
Nam Sun Wang
College Park, Md.
Rouhi Responds: It is unfortunate that my short piece gave the impression that the statements regarding safety came only from the Glutamate Association. However, as noted in the piece, the association's statements about safety always refer back to the findings of the Food & Drug Administration and other similar organizations. I checked other references, including http://www.fda.gov/fdac/features/2003/103_msg.html; an annotated paper titled "Glutamate and Monosodium Glutamate: Examining the Myths" by the International Food Information Council Foundation; a paper by John D. Fernstrom of the University of Pittsburgh School of Medicine in the Journal of Nutrition [130, 1077S (2000)]; and a paper by Bernd Lindemann, Yoko Ogiwara, and Yuzo Ninomiya in Chemical Senses [27, 843 (2002)].
The article by Fernstrom, which summarized the proceedings of an international conference on glutamate, is instructive. It states: "Although the occurrence of one or more adverse responses to MSG has been reported repeatedly in the published literature, study design has invariably left questions regarding outcome bias, either on the part of the subject or the experimenter. As discussed by several clinical investigators at the conference, by today's scientific standards, such effects rarely occur in studies in which both the experimenter and experimentee are blinded to the treatment, in which the subjects' medical conditions are adequately controlled (a particularly important consideration in the design of asthma studies), and in which the criteria for identifying MSG responders include their showing both a reproducible and positive response to MSG and a reproducible nonresponse to the placebo."
According to Fernstrom, he has not come across studies since then that suggest a change in this view.