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What if your gluten intolerance is all in your head?


While living in China from 2003 to 2005, I often served as the designated translator for fellow expatriates. Whenever we ate out, this involved asking our server which menu items contained monosodium glutamate (MSG). Invariably I was told that almost everything is made with weijing ("flavour essence"), including, on one occasion, the roast peanut appetiser my MSG-sensitive friends were snacking on as I made my enquiry.




Chinese restaurant syndrome

In April 1968, the New England Journal of Medicine published a letter by Robert Ho Man Kwok that described a strange set of symptoms: "Numbness at the back of the neck, gradually radiating to both arms and the back, general weakness and palpitation." Stranger still was the fact that Kwok, himself a Chinese immigrant, typically noted the onset of these symptoms 20 minutes after eating at restaurants serving "Northern Chinese food".

An editor at the journal titled Kwok's letter "Chinese restaurant syndrome", and thus began a minor epidemic. For countless sufferers, a mystery had been finally solved. "No MSG" signs sprang up across the US, and, eventually, the world. Study upon study confirmed the syndrome's existence and speculated about the science underlying it.

But after reading some of these studies, even a layperson will start to get suspicious. Take the editorial note that precedes Russell Asnes's article "Chinese restaurant syndrome in an infant": "The evidence that this infant had the Chinese Restaurant syndrome may be only circumstantial. However, the description of the symptom is accurate as attested to by the Editor's wife who suffers from the same malady. Incidentally, she remains a devotee of Chinese cuisine."


Despite this thorough debunking, a surprisingly large number of people – generally those who lived through the epidemic – still insist they are sensitive to MSG. Google around and you'll turn up scores of alarmist websites, which tend to combine outdated research with anecdotal, indignant rebuttals of the current scientific wisdom: "How dare you suggest my MSG sensitivity is only in my head? Why, just the other day I went out for Chinese and forgot to ask about MSG. After 45 minutes I couldn't breathe and my heart was racing."


Gluten rising

In 2007, my wife's cake shop did not offer a gluten-free option. Six years later, hardly a month goes by without a request for a gluten-free tasting. Thanks in part to celebrities such as Oprah Winfrey and Lady Gaga, nearly one-third of all consumers are now interested in gluten-free food, a multi-billion-dollar industry projected to exceed $10 billion by 2017. (Even children's play sand now comes with a gluten-free guarantee!)


Scientists are applying themselves to the riddle, and last February Slate's Darshak Sanghavi reported on an Italian study that confirmed the existence of gluten intolerance ("non-coeliac wheat sensitivity") as a third, "distinct clinical condition". In the study, one-third of patients who self-identified as gluten-intolerant did in fact experience symptom relief after adopting a gluten-free diet. Case closed, right? Pass the gluten-free pasta.

Not so fast. An important implication of the study is that two-thirds of people who think they are gluten intolerant really aren't. In light of this, the even-handed Sanghavi suggested that "patients convinced they have gluten intolerance might do well to also accept that their self-diagnosis may be wrong".


Allergic to evidence


Obviously this is not the case. For one, our memories are notoriously unreliable. You may remember getting headaches from Chinese food when in fact those memories were created when you read about Chinese restaurant syndrome in the news. The same is true for memories of gluten intolerance. Don't forget, certainty about your memories is not sufficient evidence of their truth: "Look, I know that for the last 20 years, every time I ate gluten it gave me terrible gas."

Under oath, eyewitnesses constantly forget crucial details and replace them with their own fabrications. They aren't liars – they're just human. One reason for this unreliability is that memory and perception are prone to confirmation bias. Once a bias is in place, we'll selectively remember – and notice – whatever facts help confirm it.

Food historian Ian Mosby has explained the "success" of Chinese restaurant syndrome by connecting it to racialised discourse that drew on a vision of Chinese cooking as bizarre or extreme. In the case of gluten intolerance, it doesn't take much to come up with a plausible confirmation bias. Only nine years ago, 1 in every 11 Americans was on a low-carb diet. In a country terrified of weight gain and recently obsessed with the Atkins diet, gluten makes a great villain. It's hard not to notice the theme of weight loss on gluten-free sites. Pasta, bread, cake, cookies, pretzels – they don't just make you fat, they make you sick! (Added bonus: diets motivated by a medical condition are far more effective – ask any diabetic.)

Nocebo nosh


People's desire to believe in a cure actually affects their symptoms. That's why placebo-controlled, double-blinded studies are integral to medical research. Without them, we'd be in constant danger of ascribing physiological causality to treatments that are actually psychological.



Mindful of suffering

It is here where the trouble begins. There's something intensely disturbing about the notion that we can make ourselves sick. Belief, not physiology, becomes the causal agent, displacing MSG or gluten as the source of blame for someone's suffering. This can make us feel vulnerable, stupid and weak, as though we have the choice to be better but lack the mental acuity to manage it. Not only that, it's hard not to feel like a psychological explanation trivialises one's condition – hence the expression "It's only in your head." But things that are in our heads aren't fake or unimportant (OCD? anorexia?), and susceptibility to a nocebo effect isn't a sign of weakness. Anyone can unknowingly invent a false memory or react to a substance that is actually benign.


Thinking that way is a mistake. Reductionist psychological explanations of religious beliefs can be offensive because they deny fundamental religious truths: "You believe in heaven to stave off your fear of death, not because it really exists." Legitimate psychological explanations of medical conditions, on the other hand, deny no such truths. The question of whether and to what extent MSG and gluten cause physiological reactions is scientific, not religious. When one's explanation of a medical condition becomes an unquestionable truth, the explanation is no longer scientific.

Many basic claims of nutrition science are unintuitive and sometimes don't stand up to repeated research. (Salt? Cholesterol? Vitamins? Alcohol? Coffee?) At this point, scientists simply don't have a good explanation for the mechanism and prevalence of gluten intolerance – hence the need for studies about whether it exists at all.

Maybe people have always been gluten intolerant and were going undiagnosed – as is true with coeliac disease. Maybe our guts haven't evolved to process gluten – as some advocates of the Palaeolithic diet claim. Maybe it's Monsanto (conspiracy theorists rejoice!). Maybe gluten intolerance isn't really caused by gluten, and we should actually be blaming a family of proteins in wheat called amylase trypsin inhibitors.



Alan Levinovitz is an assistant professor of Chinese philosophy and religion at James Madison University in Harrisonburg, Virginia. This article first appeared in Slate magazine


Was Chinese restaurant syndrome the gluten intolerance of its day? <i>(Image: Martin Puddy/Getty)</i>

Was Chinese restaurant syndrome the gluten intolerance of its day? (Image: Martin Puddy/Getty)


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