In last week's post, we looked at the placebo effect's evil cousin, the nocebo effect, which can lead people to experience side effects from placebo pills and believe that WiFi and wind farms are causing them to become sick. A seemingly far more common belief that also appears to be caused by the nocebo effect is the idea that monosodium glutamate (MSG), the common ingredient in oriental foods, can cause headaches and other side effects.
MSG quickly becomes glutamate when it meets with water, resulting in the taste of “umami” or the savory flavor we associate with foods such as Parmesan, soy sauce, and Roquefort — all natural sources of glutamate. Glutamate is also contained to a lesser extent in plenty of everyday foods including pork, beef, chicken, eggs, potatoes, corn, tomatoes, squid, scallops, and sardines.
Since way back in 1968, anecdotal reports of negative reactions to Chinese food have been attributed to MSG, after a letter to the New England Journal of Medicine in which the phenomenon was branded "Chinese restaurant syndrome." But despite the apparent popular consensus, this is most likely another syndrome that exists only in the mind. Decades of research summarised in a 2009 review of the literature on MSG refutes the existence of Chinese restaurant syndrome.
Negative symptoms have been reported in past studies involving MSG, but crucially, these studies were all small, uncontrolled, and unblinded, allowing the participants' expectations to impact the results. When studies have been placebo-controlled and double-blinded, there is no difference in symptoms between participants ingesting normal amounts of MSG and participants who ingested a placebo.
Recent research suggests MSG might not only not be bad for you — it could actually be used to help people eat a healthy diet, as the savory foods that stimulate umami taste buds are important for overall health. A study published recently in the journal Flavour found that old people who had lost the sensitivity of their umami taste buds complained of appetite and weight loss. The researchers measured umami sensation by placing monosodium glutamate (MSG) on specific areas of the mouth and tongue. The researchers found that giving their participants kelp tea, which is rich in MSG, resulted in improvements in salivation, taste function, and appetite.
Next time you are having dinner with someone and they mention they react badly to MSG, you might want to ask them if they have ever heard of the nocebo effect.
Sasano, T., Satoh-Kuriwada, S., & Shoji, N. (2015). The important role of umami taste in oral and overall health. Flavour, 4(1), 10.
Williams, A. N., & Woessner, K. M. (2009). Monosodium glutamate ‘allergy’: menace or myth?. Clinical & Experimental Allergy, 39(5), 640-646.
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