Some people may show an adverse reaction to monosodium glutamate (MSG). The type and number of reactions may vary between those affected, but tend to be reproducible for the individual. This may be referred to as the "Chinese Restaurant Syndrome" or "MSG Symptom Complex".
Mechanism: The reaction does not appear to be allergic (IgE-mediated). MSG may act as a neurotransmitter in affected persons.
The symptom(s) that a person typically associates with MSG exposure are termed "index" symptoms. A positive reaction to MSG was defined as having >= 2 index symptoms.
Symptoms described by affected persons:
(1) feeling of general weakness
(2) feeling of muscle tightness
(3) feeling of muscle twitching
(4) feeling of flushing
(5) sweating sensation
(6) burning sensation
(7) headache or migraine symptoms
(8) chest pain
(9) palpitations or heart pounding
(10) additional symptom associated by the patient with an MSG challenge
Headache, muscle tightness, numbness/tingling, weakness and flushing were more frequent after MSG exposure than after placebo. Yang et al identified the threshhold dose for reactivity as 2.5 grams.
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Severity of Symptom
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Description of Impact
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Points
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none
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none
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0
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mild
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noticeable but causing only slight discomfort
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1
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moderate
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definitely troublesome but not incapacitating
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2
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severe
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significant impact (incapacitating)
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3
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total score =
= SUM(points for symptoms)
average severity for positive reactions =
= (total score) / (number of positive reactions)
Interpretation:
• minimum total score: 0
• maximum total score: 30
• minimum average score: 0
• maximum average score: 3
• The higher the score, the more intense the described reaction.
