MSG Sensitivity

Also indexed as: Chinese Restaurant Syndrome

Enjoy the taste of Chinese food and other ethnic dishes without the headaches and nausea that MSG can sometimes cause. According to research or other evidence, the following self-care steps may be helpful:

Mix in a B6
Take 50 mg of vitamin B6 a day to help process MSG into harmless byproducts

Forego certain foods
Check food labels for MSG and ask restaurant staff if the Chinese or Japanese food you eat contains MSG

Skip the seasoning
Avoid Accent or Aji-No-Moto products and any foods containing these seasonings

These recommendations are not comprehensive and are not intended to replace the advice of your doctor or chemist. Continue reading the full MSG sensitivity article for more in-depth, fully-referenced information on medicines, vitamins, herbs, and dietary and lifestyle changes that may be helpful.

MSG sensitivity (sometimes 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 flavour 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 However, clinical trials have found that MSG taken without food may cause symptoms, though rarely the classic “triad” described above.⁷ ⁸ ⁹ 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.¹⁰ ¹¹ ¹²

People sensitive to MSG may also react to aspartame (NutraSweet®).¹³

Product ratings for MSG sensitivity

Science Ratings	Nutritional Supplements	Herbs
	Vitamin B6
Reliable and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit. For a herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

What are the symptoms?

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, diarrhoea, weakness, tightness of the chest, skin rash, or sensitivity to light, noise, or smells.

Medical options

Over the counter antihistamines, such as diphenhydramine (Benedryl®), might help reduce the symptoms of MSG sensitivity.

Severe reactions may be treated with prescription antihistamines such as hydroxyzine (Atarax®).

MSG sensitivity is not a universally accepted medical condition. Other than avoidance of foods containing MSG, there is no common 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 flavour enhancers, such as Accent® and the Japanese seasoning AJI-NO-MOTO™. MSG may be difficult to avoid completely, as it also occurs in hydrolysed vegetable protein, textured vegetable protein, gelatine, yeast extracts, calcium and sodium caseinate, vegetable broth, whey, smoke flavouring, malt extracts, and several other food ingredients—including “flavoring” and “natural flavouring”—without otherwise appearing on the label.

Vitamins that may be helpful

Years ago, researchers discovered that animals who were deficient in vitamin B6 could not properly process MSG.¹⁴ Typical reactions to MSG have also been linked to vitamin B6 deficiency in people.¹⁵ 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
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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. 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.

7. 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.

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

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

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

11. 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].

12. 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].

13. 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.

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

15. 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.

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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires March 2007.

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