The Origin of the MSG Controversy and the 'Chinese Restaurant Syndrome'
The negative reputation of monosodium glutamate (MSG) began in 1968, following a letter published in the New England Journal of Medicine by Dr. Robert Ho Man Kwok. Dr. Kwok described feeling symptoms like numbness and palpitations after eating Chinese food and speculated on several possible causes, including MSG. The medical journal then coined the term 'Chinese restaurant syndrome' (CRS), and the anecdotal report, fueled by xenophobic sentiments of the era, rapidly took hold in the public imagination. Despite later attempts by the FDA to clarify the issue, the stigma persisted for decades.
Clinical Studies on MSG Sensitivity
Since the origin of the CRS term, numerous studies have attempted to understand the effects of MSG on sensitive individuals. These controlled clinical trials, often double-blind and placebo-controlled, have yielded revealing results:
- Placebo Effect: Many studies, including one involving 61 self-identified MSG-sensitive individuals, showed a significant placebo effect. A notable percentage of participants reported symptoms after consuming only the placebo, suggesting a strong psychosomatic component to perceived sensitivity.
- Dose-Dependent Reaction: In the studies where participants did react specifically to MSG, a reaction was more likely to occur with high doses (typically 3 grams or more) of MSG consumed on an empty stomach. A typical serving of food containing MSG, in contrast, contains less than half a gram.
- Inconsistency of Reactions: Even those who showed a reaction to MSG in one trial often did not in repeated trials, suggesting other factors might be at play.
The Difference Between MSG Intolerance and a True Allergy
It is important to distinguish between a food intolerance and a true food allergy, as these involve different biological mechanisms and levels of severity.
Comparison: Food Intolerance vs. Food Allergy
| Feature | MSG Intolerance (MSG Symptom Complex) | True Food Allergy |
|---|---|---|
| Mechanism | No immune system involvement; issues with digestion or processing | Involves the immune system (IgE-mediated) |
| Reaction Time | Typically occurs within one to two hours after consumption | Can be immediate, within minutes of exposure |
| Symptoms | Headaches, flushing, sweating, numbness, nausea, chest tightness | Hives, swelling, wheezing, shortness of breath, anaphylaxis |
| Severity | Generally mild and self-limiting; more severe with high doses | Can be life-threatening (anaphylaxis) |
| Culprit | Excessive doses of glutamate or individual susceptibility to processing | Specific food protein (not MSG itself, but potentially other proteins in the food) |
What Might Be Behind the Symptoms?
While MSG itself is not the bogeyman it was once portrayed as, the symptoms people experience can be attributed to several factors:
- High Sodium Intake: Many processed foods that contain added MSG are also high in sodium, which can cause symptoms like flushing, thirst, and headaches.
- Processed Food Intake: The foods often containing MSG, such as canned soups, frozen meals, and fast food, are highly processed and may contain other ingredients or high amounts of fat that can cause adverse reactions.
- Psychosomatic Effect: Given the long-standing stigma, psychological factors and the nocebo effect can play a powerful role in creating perceived symptoms.
- Other Food Ingredients: It's possible that individuals may be reacting to another component within the meal, rather than the MSG itself.
How to Manage Perceived Sensitivity
For those who consistently experience adverse symptoms after eating foods with MSG, the most logical step is to avoid or limit its consumption. Managing symptoms involves focusing on overall dietary choices and being mindful of food labels.
- Read Food Labels Carefully: Look for 'monosodium glutamate' on the ingredient list. The FDA requires manufacturers to list it.
- Be Aware of Hidden MSG: The glutamate in MSG is identical to the glutamate naturally occurring in foods like yeast extract, hydrolyzed proteins, and soy extracts. While these don't have to be labeled as MSG, they can contribute to overall glutamate intake.
- Choose Whole Foods: Focus on a diet rich in whole, unprocessed foods, which naturally minimizes the intake of not just added MSG, but also excessive sodium and unhealthy fats.
- Stay Hydrated: Drinking plenty of water can help alleviate symptoms like thirst and flushing, should they occur.
Conclusion
While the concept of widespread MSG sensitivity as a harmful food allergy has been largely debunked by decades of research, the experience of a small number of people who report adverse reactions is valid. Current scientific consensus refers to this phenomenon as 'MSG symptom complex,' classifying it as a mild food intolerance rather than a severe allergy. Reactions, when they do occur, are typically linked to high doses of MSG consumed on an empty stomach and may also be complicated by the high sodium and processing levels of the foods it's added to. Ultimately, managing perceived sensitivity is about informed food choices, mindful consumption, and focusing on a balanced, whole-food diet.
It is important to differentiate science from anecdote, but also to recognize your body's personal reactions. If you suspect an MSG sensitivity, managing your intake can be a simple way to alleviate discomfort. For persistent or severe symptoms, consulting a healthcare professional is always recommended.
An excellent resource for further reading on the FDA's perspective is their Q&A page on monosodium glutamate.
