MSG Sensitivity

Also indexed as: Chinese Restaurant Syndrome

MSG sensitivity, also known as Chinese Restaurant Syndrome, is a set of symptoms that may occur in some people after they consume monosodium glutamate (MSG). The syndrome was first described in 1968 as a triad of symptoms: “numbness at the back of the neck radiating to both arms and the back, general weakness and palpitations.”1 Although some Chinese (and other) restaurants now avoid the use of MSG, many still use significant amounts.

MSG is used worldwide as a flavor enhancer. The average person living in an industrialized country consumes about 0.3 to 1.0 gram of MSG per day. MSG is classified by the Food and Drug Administration as “generally recognized as safe.” Indeed, many researchers have questioned the very existence of a true MSG-sensitivity reaction. Most clinical trials, including some double-blind trials, have failed to find any symptoms arising from consumption of MSG, even large amounts, when taken with food.2 3 4 5 6 7 However, clinical trials have found that MSG taken without food may cause symptoms, though rarely the classic “triad” described above.8 9 10 A large trial and a review of studies on MSG both suggested that large amounts of MSG given without food may elicit more symptoms than a placebo in people who believe they react adversely to MSG. However, persistent and serious effects from MSG consumption have not been consistently demonstrated.11 12 13

People sensitive to MSG may also react to aspartame (NutraSweet®).14

Checklist for MSG Sensitivity

Rating Nutritional Supplements Herbs
2Stars Vitamin B6  
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

What are the symptoms of MSG sensitivity? The symptoms of MSG sensitivity have commonly been described as headache, flushing, tingling, weakness, and stomachache. After eating meals prepared with MSG, people with MSG sensitivity may have migraine headache, visual disturbance, nausea, vomiting, diarrhea, weakness, tightness of the chest, skin rash, or sensitivity to light, noise, or smells.

How is it treated? Doctors typically recommend that people with MSG sensitivity avoid eating foods containing MSG. Severe reactions may be treated with antihistamines. MSG sensitivity is not a universally accepted medical condition. Other than avoidance of foods containing MSG, there is no conventional treatment for this condition.

Dietary changes that may be helpful: Simply avoiding MSG will prevent MSG-sensitive reactions. MSG is found in some Chinese and Japanese food and is also contained in some flavor enhancers, such as Accent® and the Japanese seasoning AJI-NO-MOTO™. MSG may be difficult to avoid completely, as it also occurs in hydrolyzed vegetable protein, textured vegetable protein, gelatin, yeast extracts, calcium and sodium caseinate, vegetable broth, whey, smoke flavoring, malt extracts, and several other food ingredients—including “flavoring” and “natural flavoring”—without otherwise appearing on the label.

Nutritional supplements that may be helpful: Years ago, researchers discovered that animals who were deficient in vitamin B6 could not properly process MSG.15 Typical reactions to MSG have also been linked to vitamin B6 deficiency in people.16 In one study, eight out of nine such people stopped reacting to MSG when given 50 mg of vitamin B6 per day for at least 12 weeks.

The actual percentage of people with MSG sensitivity who are deficient in vitamin B6 and who respond to B6 supplementation is unknown. Nonetheless, many doctors suggest that people having MSG-sensitivity symptoms try supplementing with vitamin B6 for three months as a trial.

Are there any side effects or interactions? Refer to the individual supplement for information about any side effects or interactions.

References:

1. Kwok RHM. Chinese-restaurant syndrome. N Engl J Med 1968;278:796 [letter].

2. Prawirohardjono W, Dwiprahasto I, Astuti I, et al. The administration to Indonesians of monosodium L-glutamate in Indonesian foods: an assessment of adverse reactions in a randomized double-blind, crossover, placebo-controlled study. J Nutr 2000;130(4S Suppl):1074–6S.

3. Bazzano G, D’Elia JA, Olson RE. Monosodium glutamate: feeding of large amounts in man and gerbils. Science 1970;169:1208–9.

4. Morselli PL, Garattini S. Monosodium glutamate and the Chinese restaurant syndrome. Nature 1970;227:611–2.

5. Zanda G, Franciosi P, Tognoni G, et al. A double blind study on the effects of monosodium glutamate in man. Biomedicine 1973;19:202–4.

6. Marrs TC, Salmona M, Garattini S, et al. The absorption by human volunteers of glutamic acid from monosodium glutamate and from a partial enzymic hydrolysate of casein. Toxicology 1978;11:101–7.

7. Tung TC, Tung KS. Serum free amino acid levels after oral glutamate intake in infants and human adults. Nutr Rep Int 1980;22:431–43.

8. Schaumburg HH, Byck R, Gerstl R, Mashman JH. Monosodium L-glutamate: its pharmacology and role in the Chinese restaurant syndrome. Science 1969;163:826–8.

9. Rosenblum I, Bradley JD, Coulston F. Single and double blind studies with oral monosodium glutamate in man. Toxicol Appl Pharmacol 1971;18:367–73.

10. Kenney RA, Tidball CS. Human susceptibility to oral monosodium L-glutamate. Am J Clin Nutr 1972;25:140–6.

11. Walker R, Lupien JR. The safety evaluation of monosodium glutamate. J Nutr 2000;130(4S Suppl):1049–52S [review].

12. Geha R, Beiser A, Ren C, et al. Multicenter multiphase double-blind placebo controlled study to evaluate alleged reactions to monosodium glutamate (MSG). J Allergy Clin Immunol 1998;101:S243 [abstract].

13. Geha RS, Beiser A, Ren C, et al. Review of alleged reaction to monosodium glutamate and outcome of a multicenter double-blind placebo-controlled study. J Nutr 2000;130(4S Suppl):1058–62S [review].

14. Stegink LD, Filer LJ Jr, Baker GL. Effect of aspartame and sucrose loading in glutamate-susceptible subjects. Am J Clin Nutr 1981;34:1899–905.

15. Wen CP, Gershoff SN. Effects of dietary vitamin B6 on the utilization of monosodium glutamate by rats. J Nutr 1972;102:835–40.

16. Folkers K, Shizukuishi S, Scudder SL, et al. Biochemical evidence for a deficiency of vitamin B6 in subjects reacting to monosodium-L-glutamate by the Chinese restaurant syndrome. Biochem Biophys Res Commun 1981;100:972–7.