The concurrent rise of the low-carb craze and the anti-gluten movement merely reflects the latest nutritional wisdom. A similar pattern emerged back in the 1990s, when the main dietary villains were saturated fat and cholesterol. The dietary fad of that era was the olive-oil-soaked "Mediterranean diet" and a reduced intake of meat and dairy. As doctors and dieticians urged us away from butter and ice cream, we started to become more aware of how hard it was to digest these unhealthy foods—nutritional advice became a medical problem. The second graph shows how newspaper mentions of "lactose intolerance" and "lactose sensitivity" track mentions of the "Mediterranean diet," with interest in both phenomena peaking around 1995.
I'm not suggesting that anyone who avoids gluten is secretly trying to lose weight. The purpose of a gluten-free diet is, naturally, to feel better. But there's a complicated relationship between feeling good and eating less. When a restrictive diet becomes an end in itself, we call it an eating disorder; when it's motivated by health concerns, we call it a lifestyle. That's why Hasselbeck says going G-free will make you slim (a sign of wellness) rather than skinny (a symptom of anorexia). It might also explain the relationship between food sensitivities and fad diets: People who are intolerant of gluten or lactose get a free pass for self-denial.
All this raises an important question: So what? Why is it anyone's business if some fraction of the market for gluten-free products has no particular sensitivity to wheat, barley or rye? Can't they just enjoy being G-free? I asked Alessio Fasano whether there would be any downside to jumping on the no-gluten bandwagon. "Gluten is useless," he said. "It's an intervention with no side effects, no complications. The most dangerous consequence of a gluten-free diet is the expense." (As an erstwhile Neapolitan, he did seem disturbed that people might be giving up pizza without legitimate medical reasons. "It's their fault," he said after thinking it over. "They can do what they want.")
Not every doctor agrees with Fasano. While it's certainly true we don't need gluten to thrive, the G-free lifestyle does introduce its own problems. A June advisory from the Harvard Medical School warns that packaged, gluten-free products may provide less fiber and fewer nutrients than standard supermarket options. And a recent study published in the British Journal of Nutrition found that gluten-free diets could hamper the growth of beneficial gut bacteria.
More worrisome is the fact that adhering to a gluten-free diet creates its own set of anxieties. To eliminate all wheat products from your diet is an incredibly ambitious endeavor. Web sites devoted to the topic are choked with warnings: Steer clear of oats, which might contain traces of wheat gluten; only buy pre-packaged meat, so as to avoid the contaminated deli-slicer; don't trust the "gluten-free" labels at Trader Joe's or Whole Foods; and so on. These are burden enough for adult celiac patients, but imagine the stakes for all those worried parents who have come to believe (without good scientific evidence) that dietary gluten has something to do with autism.
Then there are the more abstract costs of an unnecessary gluten-free diet. I won't dwell on the idea that eliminating wheat deprives you or your children of certain culinary pleasures. (Who isn't exquisitely sensitive to the delicious gluten in fresh-baked bread?) Still, it's worth pointing out that the G-free lifestyle can be very annoying—to friends, lovers, work-buddies, and anyone else who might have you over for dinner. For more on this, see Chapter 9 of Hasselbeck's book—"How Not To Be a Party-Pooper." Here's one way to refuse a gluten-laden treat without offending your host: "The drop: If all else fails, you take the cookie and oopsie! You are just so clumsy, it's unforgivable! No, no, you couldn't possibly have another …"
Ironically, the people who may benefit most from the current vogue are those who have been G-free all along. The proliferation of gluten-free products has made life for a full-blown celiac easier than it's ever been, and a greater awareness of gluten-related disorders has more celiac patients getting diagnosed than ever before. (There are still thought to be millions of undiagnosed cases in the United States.) Let's hope those gains aren't erased when the conventional wisdom shifts again and we leave this diet craze behind us.