You may have heard someone claim they are “allergic” to monosodium glutamate, or perhaps you think you have an MSG allergy, or you’ve been wondering if claims about MSG side effects are true.

Here’s a review of just some of the research that has been undertaken to investigate whether an MSG allergy is something to be worried about or is even real.

The first report of a reaction to MSG, back in 1968, was an anecdotal account by one person after he ate at a Chinese restaurant – it was published as a letter to the editor in the New England Journal of Medicine.1 The writer described his reaction as generalized weakness, palpitations and numbness in the arms, but acknowledged that these symptoms may have been due to any number of ingredients in the meal including sodium, or alcohol from Chinese cooking wine, and not necessarily the MSG. However the letter spawned the idea that vague reactions such as these might be attributed to monosodium glutamate (MSG) and introduced the phrase Chinese Restaurant Syndrome.

In 1995, an independent scientific panel, the Federation of American Societies for Experimental Biology (FASEB) published a comprehensive analysis of the safety of MSG and included a list of MSG symptoms and alleged side effects that reports claimed were associated with consuming foods with MSG.2

According to FDA:

FASEB’s report concluded that MSG is safe. The FASEB report identified some short-term, transient, and generally mild symptoms, such as headache, numbness, flushing, tingling, palpitations, and drowsiness that may occur in some sensitive individuals who consume 3 grams or more of MSG without food. However, a typical serving of a food with added MSG contains less than 0.5 grams of MSG. Consuming more than 3 grams of MSG without food at one time is unlikely.3

The FDA, in its Q&A about monosodium glutamate, notes: “Over the years, FDA has received reports of symptoms such as headache and nausea after eating foods containing MSG. However, we were never able to confirm that the MSG caused the reported effects.”

Research on MSG, conducted for over decades, has found that most people who believe they respond adversely to MSG do not have these reactions when evaluated in carefully controlled tests. As Food Standards Australia New Zealand concludes in its thorough review affirming MSG’s safety, “Although the prevalence of CRS (Chinese Restaurant Syndrome) has been estimated to be about 1–2% of the general population it is not clear what proportion of the reactions, if any, can be attributed to MSG. The vast majority of reports of CRS are anecdotal, and are not linked to the actual glutamate content of the food consumed. Furthermore, when individuals with a suspected sensitivity to MSG are tested in double-blind challenges the majority do not react to MSG under the conditions of the study (or react equally to placebo). Many individuals may therefore incorrectly be ascribing various symptoms to MSG, when in fact some other food component may be the cause. This highlights the need for individuals with suspected MSG sensitivity to undergo appropriate clinical testing.”4

The Bottom Line: Seek a proper medical diagnosis if you believe you are reacting to something you’ve eaten.

Allergens are well defined and packaged foods list common allergens on their labels. Sensitivities are not uncommon and can be attributed to a wide variety of foods and ingredients. In Chinese food, for example, ingredients such as peanuts, sesame seeds, shell-fish or even egg can cause reactions for some people. This is why it’s important not to self-diagnose. As with any product to which you suspect you are having an allergic-type reaction consult a healthcare professional to get a proper medical diagnosis.

References:

  1. Kwok RHM. Chinese-restaurant syndrome [letter]. N Engl J Med 1968; 278:796.
  2. Raiten DJ, Talbot JM, Fisher KD, eds. Analysis of adverse reactions to monosodium glutamate (MSG). J Nutr 1995; 125: 2892S–2906S
  3. FDA: “Questions and Answers on Monosodium Glutamate (MSG)
  4. “Monosodium Glutamate, A Safety Assessment” (Technical Report Series No. 20), Food Standards Australia New Zealand (FSANZ)

Further references can be found on Wikipedia here.

Studies Investigating MSG Allergy and “Sensitivity”:

Scientific review dismisses link between glutamate and asthma, headaches and Chinese Restaurant Syndrome

Purpose:
To review the application of glutamate in food and its benefits and role as one of the common food ingredients used.
Research Institution:
Center of Excellence for Food Safety Research (CEFSR), Faculty of Food Science and Technology, Universiti Putra Malaysia, Malaysia
Scientist(s):
S. Jinap and P. Hajeb
Results Published:
Appetite. 2010 Aug;55(1):1-10. doi: 10.1016/j.appet.2010.05.002; abstract
Conclusion:
Despite a widespread belief that glutamate can elicit asthma, migraine headache and Chinese Restaurant Syndrome (CRS), there are no consistent clinical data to support this claim. It also states that there is no consistent evidence to suggest that individuals may be uniquely sensitive to glutamate.

Discussion of four cases in which patients showed hypersensitivity reactions after the consumption of Chinese or Indonesian meals

Purpose:
Detailed discussion of four cases in which patients showed hypersensitivity reactions after the consumption of Chinese or Indonesian meals
Research Institution:
Academisch Ziekenhuis, afd. Dermatologie, onderafdeling Allergologie, Utrecht
Scientist(s):
F. de Maat-Bleeker
Results Published:
Etiology of hypersensitivity reactions following Chinese or Indonesian meals; abstract
Ned Tijdschr Geneeskd, March 1992.
Ned Tijdschr Geneeskd, December 1992.
Study Design:
Four people’s reactions were studied – two men and two women.
Study Results:
The author concludes that the patients in fact had hypersensitivity reactions to foods, namely allergy to prawns, peanuts or spices, in particular coriander, rather than to monosodium glutamate.

To review whether monosodium glutamate 'allergy' really exists?

Purpose:
To review whether monosodium glutamate ‘allergy’ really exists?
Research Institution:
Scripps Clinic, San Diego, USA
Scientist(s):
A. N. Williams and K. M. Woessner
Results Published:
Monosodium glutamate ‘allergy’: menace or myth?, Clinical & Experimental Allergy, May 2009; abstract
Study Design:
This review paper examines all of the available scientific literature relating to the possible role of monosodium glutamate in causing allergic reactions.
Study Results:
The review concludes that there is no link between the ingestion of monosodium glutamate and the development of allergies. In their conclusions, the authors state, “The current evidence does not suggest that MSG is a significant contributor to asthma, urticaria, angio-oedema or rhinitis”.

To determine whether MSG ingestion induces asthma attacks in asthmatic subjects.

Purpose:
To determine whether MSG ingestion induces asthma attacks in asthmatic subjects.
Research Institution:
Department of Molecular and Experimental Medicine, The Scripps Research Institute; and the Division of Asthma, Allergy and Immunology, Scripps Clinic
Scientist(s):
Katharine M. Woessner, Ronald A. Simon, Donald D. Stevenson
Results Published:
“Monosodium glutamate sensitivity in asthma,” Journal of Allergy and Clinical Immunology, 1999; abstract
Study Design:
With single-blind, placebo-controlled screening challenges, 100 subjects with asthma (30 subjects with a history of Oriental restaurant asthma attacks; 70 subjects with a negative history) were challenged with 2.5 g of MSG.A total of 78 patients were proved to have aspirin-sensitive asthma.
Study Results:
MSG challenges in subjects with and without a perceived sensitivity to MSG failed to induce signs or symptoms of asthma. Those who had a history of oriental asthma attacks found that their problems were not a result of MSG, but were able to identify other causes, including food allergies and heartburn caused by overeating.

A study of potential sensory side effects caused by ingesting MSG.

Purpose:
To study potential sensory side effects caused by ingesting MSG.
Research Institution:
University of Western Sydney, Australia
Scientist(s):
L. Tarasoff, M.F. Kelly
Results Published:
“Monosodium L-Glutamate: A Double Blind Study and Review,” Food and Chemical Toxicology, 1993; abstract
Study Design:

Seventy-one healthy individuals participated in a randomized, double-blind, cross-over study.The subjects were given five different oral administrations that included two placebos and three different doses (1.5, 3.0, 3.15 g/person) of MSG.

Each subject was interviewed two hours after ingestion and asked to complete a comprehensive questionnaire on their reactions.

Study Results:

One half of the participants reported they experienced one or more symptoms regardless of MSG content. The most common reaction was none at all. The study failed to demonstrate statistically significant sensitivity reactions to high levels of MSG.*The American Academy of Allergy, Asthma and Immunology considers the double-blind placebo controlled protocol to be the “gold standard” for determining food sensitivity. (S. Allan Bock M.D., Hugh A. Sampson M.D., et al. Double-blind, placebo-controlled food challenge (DBPCFC) as an office procedure: A manual. Journal of Allergy and Clinical Immunology 988; 82: 986-997.)

A study of the effects of oral consumption of MSG in people with chronic asthma.

Purpose:
To study the effects of oral consumption of MSG in people with chronic asthma.
Research Institution:
Beth Israel Hospital
Scientist(s):
Richard M. Schwartzstein, Mittie Kelleher, Steven E. Weinberger, J. Woodrow Weiss, Jeffrey M. Drazen
Results Published:
“Airway Effects of MSG in Subjects with Chronic Stable Asthma,” Journal of Asthma, 1987; abstract
Study Design:
Twelve adults with a history of asthma ingested MSG or a placebo in a double-blind, random, crossover test.
The subjects’ breathing was measured before and 4 hours after the test.
Study Results:
At no time during the observation period did any subject’s breathing change. Doctors who conducted the study concluded that asthmatics need not avoid MSG.

A test of the validity of Chinese Restaurant Syndrome among self-reported sufferers.

Purpose:
To test the validity of Chinese Restaurant Syndrome among self-reported sufferers.
Research Institution:
Department of Physiology, George Washington University, School of Medicine and Health Services
Scientist(s):
R.A. Kenney
Results Published:
“The Chinese Restaurant Syndrome: An Anecdote Revisited,” Food and Chemical Toxicology, 1985; abstract
Study Design:
Six people presenting Chinese Restaurant Syndrome symptoms consumed a liquid solution containing 6 grams of MSG and an MSG-free control solution for comparison in a double-blind test.
Study Results:
None responded only to MSG. Two of the six subjects reacted slightly to both the control solution and to the MSG solution, while the remaining four people had no reaction to either solution. The study confirmed that MSG does not cause Chinese Restaurant Syndrome in most people who claimed to suffer from the syndrome.

To develop an objective estimate of the prevalence of Chinese Restaurant Syndrome.

Purpose:
To develop an objective estimate of the prevalence of Chinese Restaurant Syndrome.
Research Institution:
The University of Texas School of Public Health, the University of Texas Health Science Center and Harvard University School of Public Health
Scientist(s):
George R. Kerr, Marion Wu-Lee, Mohamed El-Lozy, Robert McGandy, Frederick J. Stare
Results Published:
“Prevalence of Chinese Restaurant Syndrome,” Journal of American Dietetic Association, 1979; abstract
Study Design:
More than 3,000 adults, representing a cross-section of U.S. population, participated in a questionnaire survey that attempted to define the prevalence of symptoms characteristic of Chinese Restaurant Syndrome.
Study Results:
Less than 2 percent or respondents reported symptoms characteristic of Chinese Restaurant Syndrome and only 6 individuals associated these characteristics with consumption of Chinese food. In contrast, forty-three percent of respondents associated unpleasant symptoms with all kinds of foods and eating environments.