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 (鈥渇lavour essence鈥�), including, on one occasion, the roast peanut appetiser my MSG-sensitive friends were snacking on as I made my enquiry.
After observing that no one reacted to the peanuts, I was inspired to conduct a simple (and admittedly unethical) experiment. One evening, instead of translating honestly, I told my companions at a large banquet that the kitchen had promised to avoid using MSG. Everyone thanked me and happily ate their meal, dish after poisoned dish.
An hour later? Two hours later? The next day? Nothing.
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I repeated this experiment on multiple occasions, always with the same result. And yet foreigners living in China routinely complained of reactions to their food that included headaches, chest pain and shortness of breath. Was there something about my presence that conferred temporary resistance to MSG? Or could it be that MSG sensitivity was only in their heads?
Chinese restaurant syndrome
In April 1968, the New England Journal of Medicine published that described a strange set of symptoms: 鈥淣umbness at the back of the neck, gradually radiating to both arms and the back, general weakness and palpitation.鈥� 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 鈥淣orthern Chinese food鈥�.
An editor at the journal titled Kwok鈥檚 letter 鈥淐hinese restaurant syndrome鈥�, and thus began a minor epidemic. For countless sufferers, a mystery had been finally solved. 鈥淣o MSG鈥� signs sprang up across the US, and, eventually, the world. Study upon study confirmed the syndrome鈥檚 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 that precedes Russell Asnes鈥檚 article 鈥淐hinese restaurant syndrome in an infant鈥�: 鈥淭he 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鈥檚 wife who suffers from the same malady. Incidentally, she remains a devotee of Chinese cuisine.鈥�
Science, that sworn enemy of circumstantial evidence, marched on, and slowly but surely physiological explanations of Chinese restaurant syndrome began to lose credibility. Double-blinded studies failed to turn up evidence of a clinical condition. MSG, many people noted, appears in everything from . Journalists performed experiments , their results echoing the consensus of professional scientists: in the overwhelming majority of cases, MSG sensitivity is a psychological phenomenon.
Despite this thorough debunking, a surprisingly large number of people 鈥� generally those who lived through the epidemic 鈥� still insist they are sensitive to MSG. Google around and you鈥檒l turn up scores of , which tend to combine outdated research with anecdotal, indignant rebuttals of the current scientific wisdom: 鈥淗ow 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鈥檛 breathe and my heart was racing.鈥�
Occasionally, as with vaccines and climate change denial, alarmism veers into paranoia, yielding accusations that a shadowy east Asian cabal is paying off scientists and journalists to regurgitate their propaganda. (, I await your cheque!). For a small minority, MSG sensitivity somehow became more than a medical condition, and challenging its physiological basis poses a threat to their very identity. The harmfulness of MSG, a seemingly trivial assertion, took on the importance of a religious doctrine, a fundamental truth to be defended at any cost. But why?
Gluten rising
In 2007, my wife鈥檚 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, are now interested in gluten-free food, a projected to exceed $10 billion by 2017. (Even now comes with a gluten-free guarantee!)
This is very perplexing, given that only and only . What could possibly be causing widespread reports of non-coeliac gluten intolerance, for a raft of symptoms including gas, bloating, diarrhoea, constipation, fatigue, goose bumps, dizziness, infertility, migraines, joint inflammation and even mood disorders?
杏吧原创s are applying themselves to the riddle, and last February Slate鈥荣 on an that confirmed the existence of gluten intolerance (鈥渘on-coeliac wheat sensitivity鈥�) as a third, 鈥渄istinct clinical condition鈥�. 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鈥檛. In light of this, the even-handed Sanghavi suggested that 鈥減atients convinced they have gluten intolerance might do well to also accept that their self-diagnosis may be wrong鈥�.
Predictably, the comment thread exploded with rebuttals: defensive anecdotes, doctrinal pronouncements about the evils of gluten and accusations of corporate malfeasance, all of which bear a striking resemblance in tone and content to the rhetoric of anti-MSG advocates. For many, the truth of physiological gluten intolerance has now acquired a quasi-religious status.
Allergic to evidence
No one likes to be told they are mistaken about the foundation of their most dearly held beliefs. It offended the faithful when Karl Marx suggested that religions are psychological tools meant to placate the masses. Suggesting that gluten intolerance might have a psychological basis threatens a similarly foundational belief, namely that we are rational beings, competent interpreters of reality immune to mass hysteria and self-deception.
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鈥檛 forget, certainty about your memories is not sufficient evidence of their truth: 鈥淟ook, I know that for the last 20 years, every time I ate gluten it gave me terrible gas.鈥�
Under oath, eyewitnesses and replace them with their own fabrications. They aren鈥檛 liars 鈥� they鈥檙e just human. One reason for this unreliability is that memory and perception are prone to confirmation bias. Once a bias is in place, we鈥檒l selectively remember 鈥� and notice 鈥� whatever facts help confirm it.
Food historian has explained the 鈥渟uccess鈥� of Chinese restaurant syndrome by connecting it to that drew on a vision of Chinese cooking as bizarre or extreme. In the case of gluten intolerance, it doesn鈥檛 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鈥檚 hard not to notice the theme of weight loss on . Pasta, bread, cake, cookies, pretzels 鈥� they don鈥檛 just make you fat, they make you sick! (Added bonus: diets motivated by a medical condition are far more effective 鈥� ask any diabetic.)
Nocebo nosh
Confirmation bias meets physiology in the placebo effect, a well-documented phenomenon in medical treatments ranging from sham drugs to sham acupuncture (where ) to .
People鈥檚 desire to believe in a cure actually affects their symptoms. That鈥檚 why placebo-controlled, double-blinded studies are integral to medical research. Without them, we鈥檇 be in constant danger of ascribing physiological causality to treatments that are actually psychological.
Needless to say, placebo effects aren鈥檛 always beneficial. Strong belief can also render a harmless substance poisonous, which is exactly what happened with MSG. 杏吧原创s refer to this as the nocebo effect, and it means that careful studies are necessary to distinguish between poisons and poisonous beliefs.
None of this minimises the relief felt by those who undergo sham acupuncture, or the symptoms of those who think they are gluten intolerant. Pain is pain; chronic diarrhoea is chronic diarrhoea. All it means is that pain relief might not be caused by the physical presence of an acupuncture needle, and diarrhoea might not be caused by the physical presence of gluten. In these instances, the symptoms may be real, but their cause (and potential resolution) is all in our heads.
Mindful of suffering
It is here where the trouble begins. There鈥檚 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鈥檚 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鈥檚 hard not to feel like a psychological explanation trivialises one鈥檚 condition 鈥� hence the expression 鈥淚t鈥檚 only in your head.鈥� But things that are in our heads aren鈥檛 fake or unimportant (OCD? anorexia?), and susceptibility to a nocebo effect isn鈥檛 a sign of weakness. Anyone can unknowingly invent a false memory or react to a substance that is actually benign.
Accepting a psychological explanation of gluten intolerance is especially difficult because food aversions often turn into a way of life. Like religion, avoiding gluten requires personal sacrifice. Gluten intolerance creates communities, which, like religious communities, share stories of suffering and redemption, and share meals made special by the presence of a food taboo. It鈥檚 no wonder people take offence at the suggestion that gluten intolerance could be psychological 鈥� after all, who wants to have built their way of life on a 鈥渕ere鈥� trick of the mind?
Thinking that way is a mistake. Reductionist psychological explanations of religious beliefs can be offensive because they deny fundamental religious truths: 鈥淵ou believe in heaven to stave off your fear of death, not because it really exists.鈥� 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鈥檚 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鈥檛 stand up to repeated research. ( Cholesterol? ) At this point, scientists simply don鈥檛 have a good explanation for the mechanism and prevalence of gluten intolerance 鈥� hence the need for studies about .
Maybe people have always been gluten intolerant and were going undiagnosed 鈥� as is true with coeliac disease. Maybe our guts haven鈥檛 evolved to process gluten 鈥� as some advocates of the Palaeolithic diet claim. Maybe it鈥檚 (conspiracy theorists rejoice!). Maybe gluten intolerance isn鈥檛 really caused by gluten, and we should actually called amylase trypsin inhibitors.
None of these explanations is 鈥渙nly鈥� in our heads, which makes them feel more acceptable. But to deny the distinct possibility that gluten could be another MSG, at least for some people, is to deny what science has confirmed, again and again, about our nature as human beings.
So when some annoying friend implies that your gluten intolerance is psychological, go right ahead and be offended. But when science suggests it? Best to listen up, question your self-diagnosis, and remind yourself that nocebo effects are nothing to be ashamed of.
