MSG: How a Friendly Flavor Became Your Enemy

Today we're going to pull up a seat at our favorite restaurant, order our favorite meal — and whether we want to or not, we're going to gorge down on glutamic acid, better known in its commercial form as MSG. Although vilified by many, glutamic acid is something we all eat lots of every day, as it occurs naturally in our bodies and our food, and yet it is strangely claimed to produce a staggering array of unpleasant symptoms when any additional amount is added to our food as a flavoring agent. This is the story of MSG, and how it went from being a natural and important amino acid, to a favorite flavoring for chefs all around the world, to being reviled as a threat to your health.

Let's take a quick look at the basics of MSG, perhaps already familiar to you. It's monosodium glutamate, a molecule of the common amino acid glutamate (also called glutamic acid) with a single sodium ion attached. Glutamic acid is everywhere. It naturally occurs in many foods, so much so that the average adult diet includes 13 grams of it every day. It's also a primary neurotransmitter in our brains, playing critical roles in nutrition, metabolism and signaling. It's so ubiquitous that nobody gets away from it; it's throughout your body naturally, and it would scarcely be possible to concoct a protein-containing meal free of it. Yet the reason we're talking about it today is that it has another important quality: it's tasty. Very tasty. Just as it has with sugar and fats, our body has evolved to crave the nutrients that it needs the most. Glutamic acid — the crucial component of MSG — is just such a nutrient.

This was discovered in 1908 by a Japanese researcher at Tokyo Imperial University, Professor Kikunae Ikeda, who noted that broth made from the popular and yummy seaweed called kombu had a taste that didn't seem to be included in (what were then) the four basic flavors: sweet, salty, sour, and bitter. He isolated the taste and named it umami — which we call savory — and found that it was coming from the glutamic acid in the seaweed. He experimented with all sorts of different glutamate salts that would permit the glutamic acid to be crystallized in the same way regular salt is, allowing it to be conveniently used in meal preparation, and he found that monosodium glutamate did this best without losing or changing the flavor. Ikeda filed a patent, and ever since then, MSG has been one of the world's favorite flavorings, and for over a century we've now been counting five basic flavors. (If you want to know what it tastes like, think of parmesan cheese, which gets nearly all its flavor from the glutamic acid it contains.) It hit the store shelves in Japan as a retail product called Ajinomoto. By 1931, there was a shaker of it on every restaurant table and on every chef's spice rack.

And thus began a strange, strange journey through the cultural currents of the twentieth century. Ajinomoto swept through Japan's island colony of Taiwan, but initially failed to make the jump to the Chinese market, which had very similar cuisine to Taiwan. The reason? Ajinomoto was a symbol of Japanese imperialism, profoundly offensive to the Chinese. Yet it was an excellent fit with Chinese cooking, especially as a savory vegetarian alternative to meat. So the Chinese knocked it off, selling their own copies with Chinese names and Chinese packaging; and very soon, these copies were outselling the original.

In these same pre-war years, Ajinomoto also found a market in the United States; not to consumers, but to major food manufacturers, most notably Campbell's Soup, for years the world's single largest buyer of MSG. Then with the approach of war with Japan came an intensifying focus on quality food for soldiers, and the need for good morale led to massive adoption of MSG for field rations. After the war, MSG dominated the frozen foods market. It was everywhere, to the point that chefs in Asia began to snub it as an ingredient, feeling that it had made all food taste the same.

And then, at the height of MSG's popularity, twentieth century culture dealt it its biggest blow. The 1960s saw the explosion of the Western esotericism movement; a rejection of all things artificial and the embrace of all things natural — a focus on origin only, with no regard for actual content or safety. As Westerners reveled in post-war abundance, juggernaut environmental movements rose to vilify just about anything tainted by human intervention. Food additives were targeted early on. Curiously, amid this vast wave of chemophobia as a fashion statement, it was a single short letter to the editor published in a scientific journal — hardly an epicenter for pop culture — that cemented MSG's place on the list of public bogeymen.

The letter was from a Chinese-American doctor, Robert Ho Man Kwok, living in Maryland. It was published in 1968 in the New England Journal of Medicine. Kwok wrote:

For several years since I have been in this country, I have experienced a strange syndrome whenever I have eaten out in a Chinese restaurant... The syndrome, which usually begins 15 to 20 minutes after I have eaten the first dish, lasts for about two hours... The most prominent symptoms are numbness at the back of the neck, gradually radiating to both arms and the back, general weakness, and palpitation.

Addendum: A recent claim that this letter was written as a prank has been debunked. Regardless, what matters is the impact that the letter had, no matter who wrote it or why. —BD

Kwok hypothesized the potential causes being the soy sauce, the cooking wine, the high sodium content, or... the MSG. The editors gave his letter the headline "Chinese Restaurant Syndrome". The letter was ravenously devoured by the esotericists, jubilant that there was a new artificial food ingredient that could arguably be framed as dangerous. Even the fact that Kwok was Chinese played a role: 1968 was when the idea of Chinese enlightenment was just beginning to spread like wildfire through American culture, launching the fads of acupuncture and meditation and traditional herbal remedies. It played perfectly into the esotericism movement. Even in the medical sciences, Kwok's letter triggered a flurry of more such letters, filling the literature with anecdotal warnings and fears about MSG. In Japan, sales of Ajinomoto dropped for the first time ever as popular books were published repeating all the worst of the American claims.

Ever since then, through to the present day, people have been self-diagnosing with MSG sensitivity. The claimed symptoms have broadened considerably, popularly including just about any negative symptom that a person might feel: headaches, sweating, anxiety, numbness, palpitations, chest pain, nausea, weakness, dizziness, and facial flushing, tingling, or pressure.

So let's look into these claims of symptoms. First, it's important to note that whatever effects MSG may or may not have, sensitivity to it is not an allergy. This is an important distinction, and it's a very commonly believed piece of misinformation. Allergies involve IgE (Immunoglobulin E), an antibody produced by your immune system. Any potential sensitivity to MSG, however, is not mediated by IgE. The reason this is so important is that the treatments for allergies and sensitivities are different, and even those who have self-diagnosed with severe MSG sensitivity need not worry about the worst allergic reactions like anaphylactic shock. It's completely unrelated, despite much widely available information on the Internet warning of the dangers of "MSG allergies".

In 1995, the US Food & Drug Administration set out to resolve the question of MSG sensitivity once and for all. They contracted with FASEB (the Federation of American Societies for Experimental Biology) to assemble an Expert Panel to review all of the existing research on MSG. Their final report, which is 350 pages long, is called Analysis of Adverse Reactions to Monosodium Glutamate. What they found is interesting. An average person gets 13 grams of glutamate in their normal daily diet, with only about half a gram of that (about 4%) in the form of added MSG. So MSG is a pretty small contributor to the amount of glutamate that anyone gets. Research found no adverse effects from this. Meaning that if you consume MSG in a normal amount in the normal way, exhaustive controlled testing has found that even people who self-diagnose as MSG sensitive do not experience any symptoms that correlate to the MSG in their meal. However, the Expert Panel was able to identify two groups of people who may experience symptoms.

The first of these were healthy test subjects who were given 3 grams of MSG on an empty stomach with no other food — just the MSG — about six times as much as the average person gets in a whole day of meals. When given this extreme amount, a small number of test subjects reported feeling some of the symptoms within one hour, though the symptoms were both minor and transient and soon disappeared. Given anything less than that, no blinded and controlled trials have ever found that people experience any negative symptoms as a result of MSG in their food.

To put that in perspective, it's comparable to being given three tablespoons of salt on an empty stomach with no other food (that's six times what the average person gets in a day). What symptoms would you experience? It doesn't really matter, because nobody ever does that.

The second group was people with severe asthma, but only when given MSG in a meal containing no carbohydrates or other proteins. This was reported in eleven different studies on asthmatics and MSG. However, the Expert Panel found that all eleven studies were either methodologically flawed, and/or the evidence they found was too weak to justify the conclusion. So the best the panel could do on the issue of severe asthmatics was to recommend that it be properly studied.

But the bottom line was that the FASEB report found MSG to be safe, and reconfirmed its FDA designation as "generally recognized as safe" (GRAS). Later research continues to find the same thing; a major review in 2006 of 40 years of testing concluded "there is no consistent evidence to suggest that individuals may be uniquely sensitive to MSG", and this finding is repeated time and time again despite continued calls from natural food proponents to have MSG banned.

As nearly every article on the history of MSG lays the ultimate blame for Americans' aversion to MSG on anti-Asian racism, a word on that is needed. When Dr. Kwok's letter was published, there was a tradition in the New England Journal of Medicine to print satirical and comical replies. Of those that followed Kwok's letter, many were bursting at the seams with unabashedly racist mocking of Chinese words and Chinese food in general, even extending to off-color limericks. The gist of it all was that Chinese food and culture itself was enough to make one feel ill, and indeed very little attention was given to Kwok's actual MSG theory.

Update: An earlier version of this failed to include the role racism played in the rise of anti-MSG sentiment. —BD

At the same time — outside of the Old Boys' Club of the NEJM — esoteric rejection of artificial food additives was swelling from an isolated hippie fad into the tidal wave of mainstream pop culture. Whether Dr. Kwok had ever written his letter or not, MSG's fate was sealed. It joined the ranks of added sugar and preservatives and artificial colorings. No matter how many NEJM correspondents made fun of egg foo yung and bird's nest soup, MSG was an artificial food additive and it was doomed. It was a double whammy. Today Americans grow up only ever hearing of MSG in Chinese restaurants -- never in steakhouses or Italian restaurants where it's equally popular. And just to remind us that no cultural trend is simple, all of this was going on during an era of fetishism over Eastern wisdom.

So here's the bottom line. If you, like many people around the world, suffer symptoms reliably when you eat a meal with added MSG, consider talking to a doctor or a registered dietitian. You may indeed have some food sensitivity; however, be ready for the news that it's not what you thought it was. It may be the nocebo effect (your expectations of reacting to the perceived presence of MSG), or it may be something else in the food — but it's almost certainly not the MSG; unless you happen to be eating it by the tablespoon with nothing else.

By Brian Dunning
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