For more than half a century, monosodium glutamate (MSG), a savory flavor enhancer, has been unfairly targeted, with people attributing a range of symptoms, including headaches, indigestion, flushing, and acid reflux, to its consumption. Chinese restaurants, in particular, have borne the brunt of this condemnation. But is MSG truly harmful, or is there more to the story? According to the U.S. Food and Drug Administration (FDA), MSG is considered safe for consumption, as concluded by a study commissioned by the agency. MSG is simply the sodium salt of the amino acid glutamic acid (and, despite its name, contains no gluten). The 1995 FDA study did report a few instances of mild, short-term symptoms such as headache, flushing, or drowsiness in individuals sensitive to MSG who consumed a large amount (3 grams or more) without food. However, a typical serving of food containing added MSG has less than 0.5 grams. Consuming more than 3 grams of MSG without food at once is highly unlikely.
If the evidence surrounding MSG’s safety was clear decades ago, why does the fear persist? The long-held apprehension surrounding this umami-boosting ingredient originates from an old letter, a series of poorly conducted studies, and media hysteria from the 1960s onwards. In 1968, a Maryland doctor, Robert Ho Man Kwok, penned a letter to the New England Journal of Medicine describing symptoms – numbness, weakness, and heart palpitations – after eating Northern Chinese food. He coined the term “Chinese Restaurant Syndrome” and suggested three possible culprits: salt, cooking wine, or MSG. MSG was originally isolated and patented by a Japanese chemist, Kikunae Ikeda, in the early 1900s. It became a common additive in East Asian cooking. By around 1926, MSG was making its way to the U.S. through two channels: Chinese restaurants and canned foods, such as those produced by Campbell’s Soup Company. By the time of Kwok’s letter, MSG was widely found in processed, packaged, and restaurant-prepared foods, and even considered a household spice.
Several doctors and scientists responded to Kwok’s letter, describing their own experiences with “Chinese Restaurant Syndrome,” but there was little overlap in their symptoms. Dr. Howard Steel, an orthopedic surgeon, even suggested that the entire exchange was a hoax, wagering that he could get published in the prestigious New England Journal of Medicine. The media, however, latched onto the narrative, publishing headlines like “Chinese Restaurant Syndrome” and stigmatizing Chinese cuisine. Initially, no specific ingredient was singled out, as Kwok had suggested three potential causes for his alleged ailments. But between 1968 and 1969, a series of poorly designed studies aimed to establish Chinese Restaurant Syndrome as a medical condition triggered by MSG. “When you look at the trials, it’s pretty extreme,” stated Dr. Andrew Cohen, a headache specialist and assistant professor of medicine and neurology at the Icahn School of Medicine at Mount Sinai in New York, who recently published a review on the topic. These early trials, forming the basis for MSG’s negative reputation, were heavily biased. Unblinded studies were conducted on individuals who had already experienced negative reactions to food at Chinese restaurants, seeking to confirm those reactions. Unsurprisingly, they found what they were looking for. Later studies investigated MSG’s health effects in mice, linking it to brain lesions and obesity. However, in these cases, MSG was injected under the skin rather than ingested as humans would, and administered in extremely high doses.
As researchers continued to publish flawed and misleading studies, and the media amplified their findings, public perception solidified. MSG was perceived as a poison, and Chinese restaurants became the scapegoat. Chinese restaurants began displaying “No MSG” signs in their windows. Food manufacturers followed suit, adding the same language to their packaging. In 2024, Yelp reviews still abound with discussions of MSG-induced symptoms, even though the phenomenon has been widely debunked. “Fast food and snacks are usually high in MSG, but do not carry the same extent of complaints,” added Dr. Katie Shelke, principal scientist at Corvus Blue LLC, a food science and nutrition research and regulatory affairs firm based in Chicago. She further pointed out that foods like tomatoes, mushrooms, and Parmesan cheese naturally contain MSG, but there’s no mention of “Italian Restaurant Syndrome.”
Shelke suggested that the power of suggestion should also be considered. The stigma surrounding MSG and Chinese food exemplifies the “nocebo” effect: the phenomenon where negative expectations or beliefs about a substance lead to unpleasant symptoms, even in the absence of any physiological cause. In other words, individuals can experience real reactions, such as headaches, flushing, or nausea, simply because they’ve been told to expect them. Cohen’s team found that while MSG could potentially trigger headaches, many studies used doses much higher than normal consumption. Clinical trials reported “conflicting results,” and the role of MSG in causing migraines remains unclear, the researchers wrote in their review. Cohen noted that various ingredients, like alcohol, dairy, or eggs, are generally considered safe but can still trigger headaches in some individuals. Although MSG can potentially trigger headaches, “a lot of people think it is when it’s not,” he concluded.
