Tucket News HubIn 1908, Japanese chemist Kikunae Ikeda set out to discover the source of the rich savouriness of his wife’s sea kelp broth.
Upon discovering that the amino acid glutamate was responsible for the broth’s satisfying flavour, he named this distinctive taste “umami”, which translates to “pleasant savoury taste”.
Going on to market it as the water-soluble sodium salt, monosodium glutamate (MSG), the popularity of this flavour enhancer exploded across Japan, China, and Southeast Asia. By the late 1940s its adoption had also become widespread throughout the United States, appearing in everything from canned soups and TV dinners to military rations.
For decades millions of people had used MSG without problem – and then in 1968, everything changed with a brief letter to the editor of the New England Journal of Medicine (NEJM). Dr Robert Ho Man Kwok, a Maryland paediatrician, described his symptoms of numbness, weakness and palpitations after eating out at Chinese restaurants, pondering whether they might be due to excessive salt, the cooking wine, or perhaps the food seasoning MSG.
His letter, catchingly titled Chinese Restaurant Syndrome, resulted in numerous responses from other doctors over the following months. Some reported similar experiences, while others, including the NEJM editors, were sceptical: why did different people report completely different symptoms; why did some people experience symptoms almost immediately, others much later; why was the phenomenon reported in some areas but not at all in other towns and cities? Curiously, all the symptoms associated with the syndrome – such as palpitations, dizziness, and headaches – could be triggered simply by anxiety.
Many of the responses to Dr Kwok’s letter adopted a satirical tone, using humour and irony to critique the perceived overreaction to MSG. Even the earnestness of Dr Kwok’s original letter was questioned given he signed off as the senior research investigator at the National Biomedical Research Foundation, an institute for which no record could be found.
But newspapers, not letting facts get in the way of a good story, dropped the scepticism and satire of the NEJM conversations and ran with the dramatic story of a “Chinese Restaurant Syndrome”, and how doctors were concerned the food additive MSG was making people ill. It caught the public imagination, and an urban myth was born – driven by a toxic mix of chemophobia and xenophobia.
The 1960s were a time of increasing concern over food additives such as preservatives and artificial sweeteners, though this was often combined with an irrational fear of anything “chemical”. A refined white powder being added to food with the chemical-sounding name “monosodium glutamate” was an easy target for stoking people’s chemical fears. And there was also considerable anti-Asian sentiment in the United States, a cultural bias that made it easy for people to single out Asian-style food as suspect and potentially harmful.
In the face of declining business, Chinese and other Asian restaurants displayed “No MSG” on their signage and menus, and food manufacturers started removing MSG from their products.
Most people didn’t stop to think why this problem had just suddenly appeared; nor did they stop to wonder how glutamate, a common, naturally occurring component of food, could be causing problems. Cheese, tomatoes, mushrooms, and human and cow’s milk are just some of the foods that contain free (unbound) glutamate. Moreover, glutamate is the most prevalent amino acid in dietary protein, and during digestion this protein-bound glutamate is released and subsequently absorbed.
Consequently, glutamate is abundant in the
human diet, and the addition of MSG as a flavour enhancer contributes only a small percentage more – below normal daily fluctuations. Many people, while diligently steering clear of Chinese restaurants and foods containing added MSG, were unknowingly preparing meals at home with even higher levels of glutamate!
Some argued that MSG’s sodium content might pose a health problem by increasing sodium consumption. But, because both salt and MSG enhance flavour, substituting some salt with MSG – which contains just 12 percent sodium compared to salt’s 39 percent – lowers overall sodium intake.
In the wake of Dr Kwok’s letter, several scientific studies reported associations between MSG and negative health outcomes. However, the scientific community strongly criticised these early studies, noting that they relied on anecdotal evidence or were based on poorly designed, unblinded experiments that did not control for the nocebo effect – where just the expectation of harm can lead to negative health outcomes.
Unfortunately, people often don’t pay much attention to the details of how studies are run, and those methodologically flawed studies fed into the public narrative that MSG was harmful – the public panic over MSG continued to build.
Subsequent, high-quality, placebo-controlled studies failed to show any reproducible adverse effects for MSG consumed with food. Notably, individuals who self-identified as having adverse reactions to MSG failed to do so under placebo-controlled, double-blind conditions, and ongoing scientific reviews continue to affirm the safety of MSG as a flavour enhancer.
Nevertheless, many people continue to avoid MSG; even when the science is clear, urban myths and persistent biases can be difficult to overcome. Unfortunately, “MSG free” labelling remains a selling point and continues to reinforce the notion that MSG is harmful.
Misinformation and rumour have given MSG an undeserved bad reputation. It’s a useful kitchen seasoning that can enhance the flavour of a wide range of meals while lowering salt use.
Health scientist Dr Steve Humphries is a director at Hebe Botanicals in Ōtaki. He was previously a lecturer at Massey University and director of the Health Science Programme.
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