Hypertension in patients taking MAOIs who had eaten certainfoods (soy sauce,chicken nuggets) has been attributed, in anecdotal reports, to an interaction with monosodium glutamate. However, a small controlled study found no evidence to support thisidea, and reaction was probably related to tyramine,.
Five healthy subjects were given monosodium glutamate 400 to 1600mg or a placebo with or without tranylcypromine for at least 2 weeks. Episodes of hypertension were seen in 2 subjects taking tranylcypromine with both placebo and monosodium glutamate,but no changes in blood pressure or heart rate occurred that could be attributed to an interaction while taking monosodium glutamate. The largest dose of monosodium glutamate used was about twice amount usually found in meals containing large amounts of monosodium glutamate (See reference number 1).
There have been anecdotal reports of hypertensive reactions in patients taking MAOIs that were attributed to interactions with monosodium
Monosodium glutamate alone can cause a small rise in blood pressure,and MAOIs alone very occasionally cause hypertensive episodes. However, reactions reported with soy sauce and chicken nuggets were probably due to a high tyramine content, as a high tyramine content has subsequently been detected in some soy sauces,(See reference number 4) (see also MAOIs or RIMAs + Tyramine-rich foods interaction).
No interaction between monosodium glutamate per se and MAOIs has been established, although it should be pointed out that number of subjects studied was very small. It is quite possible that anecdotal reports were due to tyramine content of foods, and not to monosodium glutamate. In Hong Kong,patients on MAOIs are not advised to avoid monosodium glutamate, but are instructed to avoid excessive soy sauce because of its possible high tyramine content (See reference number 4).
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Pohl R,Balon R, Berchou R. Reaction to chicken nuggets in a patient taking an MAOI. Am J Psychiatry (1988) 145, 651.
Lee S,Wing YK. MAOI and monosodium glutamate interaction. J Clin Psychiatry (1991) 52,