The gluten-free craze is out of hand. Here are 8 facts to counter the madness.

The gluten-free craze continues in the United States, fueled by celebrities such as Gwyneth Paltrow and well-debunked books like Wheat Belly.

By 2016, Americans are expected to spend more than $15 billion on gluten-free products, with up to one-third telling pollsters they're trying to cut gluten from their diets. While the US leads the trend, the rest of the world is now catching up. I saw this globalization firsthand in a tiny town in pasta-obsessed Italy: a small restaurant boasted a "menu senza glutine" — or gluten-free menu.

What makes this obsession so stunning is that for most people, there's not really any good scientific evidence to support abstaining from grains. As the New Yorker’s resident debunker Michael Specter summed up, there are simply no "scientifically satisfying answers" for the question of how gluten, "a staple food that has sustained humanity for thousands of years, [has] suddenly become so threatening."

Gluten is a protein composite that gives shape to grains like wheat, rye, and barley. It's true that some people can't tolerate it: those with wheat allergies, for example, or celiac disease. But that's only a tiny fraction of the population, and it's not enough to explain the overwhelming enthusiasm for this pattern of eating.

Many of us are going gluten-free without any scientific reason for doing so, and gluten is being blamed for a plethora of pathologies, including dementia, depression, obesity, autism, and ADHD. Some people also insist that abstaining from gluten can actually help with weight loss — a major reason acolytes avoid grains in their diets. Science, as you might expect, suggests the relationship between gluten and health is much more complicated than that.

1) Gluten is found in lots of foods — but gluten-free options are growing

By 2016, Americans are expected to spend more than $15 billion on gluten-free products. (ChameleonsEye)

Gluten is a composite of two proteins, glutenin and gliadin, found in foods processed from wheat and other grains, including barley and rye. To avoid gluten, you have to stay away from all wheat-based foods and ingredients, from white and whole-wheat flours to kamut, spelt, semolina, and wheat bran and germ.

That means no bread, pasta, couscous, cookies, cakes, muffins, pastries, cereals, crackers, gravies, or beer. Less obviously, it also means no soy sauce, bouillon cubes, candies, food starch, fried foods, or even oats if they're processed in the same facility as wheat.

The growing demand for gluten-free products has given rise to alternatives to all of the above. A quick search on Amazon.com brings up everything from gluten-free pancake mix and granola bars to "gluten-free" almond meal and lollipops. This offering is now growing even faster than vegetarian options. Sales of alternatives to meat have been flagging in America since 2008, the Economist reported: "Consumer demand for products without gluten, however, is rising rapidly."

2) A tiny fraction of people have celiac disease or wheat allergies and truly can't eat gluten

Bread is seen as a dietary enemy by many, despite the fact that it's a minority of people who are actually allergic. (Universal Images Group.)

There are definitely real, gluten-related disorders that people have to cope with. Celiac disease is a serious, diagnosable autoimmune condition that causes people's immune systems to violently attack their small intestine whenever they eat gluten. About 1 percent of Americans have celiac disease, and, according to the National Foundation for Celiac Awareness, many of them go undiagnosed or misdiagnosed for years — suffering through pain from eating unnecessarily.

Even more rare are genuine wheat allergies, which affect an estimated 0.1 percent of people in Westernized countries. Gluten-free products can certainly be used by those with this allergy, but, as a review article on gluten-free diets pointed out, "Because wheat allergy can be treated with wheat avoidance, a wheat-free diet may be more permissive than a strict gluten-free diet."*

On top of that, there is some evidence to suggest gluten-free eating patterns can also improve symptoms in people with irritable bowel syndrome, rheumatoid arthritis, type 1 diabetes, and psoriasis. Again, this all adds up to a small portion of the public, however. We simply don't have science to support a gluten-free diet for the general population.

3) For the rest of us, the science behind "gluten sensitivity" or "gluten intolerance" is foggy

There is a much larger number of people who are cutting gluten from their diets in the hope of alleviating or avoiding a range of symptoms and diseases — bloating, obesity, brain fog, Alzheimer's, and autism. And the evidence that this is a good idea is much, much less clear.

A French blogger perfectly captured the ridiculousness of the fad by eliminating gluten-rich foods from classic scenes in arts and entertainment. (Gluten Free Museum)

Sometimes, these individuals consider themselves to have "non-celiac gluten sensitivity" or "non-celiac gluten intolerance." To date, there are no firm diagnostic criteria yet, nor are there gluten-sensitivity tests, so determining whether someone has this condition is very subjective: it mostly involves putting someone on a gluten-free diet and seeing how they report feeling afterward.

(Gluten Free Museum)

This poses a dilemma, of course, and makes a diagnosis subjective. Studies — such as this one in the journal Gastroenterology — have found that many people who think they have non-celiac gluten sensitivity actually don’t. Some wonder whether gluten sensitivity truly exists, or if there's something else going on.

An alternative hypothesis suggests that people who say their symptoms improve on a gluten-free diet may actually be reacting to another set of carbohydrates in wheat called called FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides and polyols). In other words, it's not the gluten that's bothering people, but other sugars found in wheat.

(Gluten Free Museum)

Still, research on this is in the very early stages. Many of the studies involving people with gluten sensitivity or FODMAPs diets are tiny, and the science is still very much working itself out.

One of the leading researchers in the area, Dr. Umberto Volta from the University of Bologna in Italy, put it this way: "This is an emerging condition mainly self-reported by people who claim an association between foods containing gluten and digestive symptoms." While some self-report an improvement in symptoms, this is usually "a result of a placebo effect unavoidably related to the elimination diet." When these patients are assessed more thoroughly, he added, it's often other factors — lactose intolerance, FODMAPs — rather than gluten that cause their discomfort. Still, gluten gets the blame.

4) "The vast majority of people who think they react to gluten don’t"

For now, non-celiac gluten sensitivity remains a little-understood condition in need of scientific validation and objective diagnostic criteria. There may be some people who turn out to have stomach problems brought on by gluten or something else that lurks in grains. But even then, the available research suggests it’s only a tiny fraction of the population (between 0.63 percent and 6 percent) that has any sensitivity to these foods. (Remember: 33 percent of Americans say they want to avoid gluten.)

"The state of science right now, as best we know is this: the vast majority of people who think they react to gluten don’t," Alan Jay Levinovitz, author of the new book The Gluten Lie, told me in an interview. "There may be a small segment of the population sensitive to gluten and who don’t have celiac disease, and only time will tell if that really is something."

So the decision to avoid gluten for a range of health benefits in no way reflects the current science, and we really do not have any evidence-based reason to believe that gluten is causing masses of people health harms.

5) There's no evidence that going gluten-free will help you lose weight

Gwyneth Paltrow, a leading proponent of a gluten-free diet. (Donato Sardella/Getty Images)

Beyond alleged sensitivity or intolerance, another reason many people try a gluten-free diet is because they think it'll help them lose weight. A 2014 survey of dietitians found that the anti-wheat sentiment was the top dieting trend of the year. But, interestingly, science says gluten-free diets may actually cause people to gain weight.

For his new book Is Gwyneth Paltrow Wrong About Everything?, author Tim Caulfield combed through the science behind the gluten-free craze and came to this conclusion: "Despite claims to the contrary, no credible study has shown that gluten/wheat is the cause of the current obesity epidemic; there is also no credible evidence to suggest that eliminating gluten and wheat from your diet is a wise lifestyle choice."

Caulfield pointed to a 2006 study that tracked 371 gluten-free dieters. The result? Eighty-two percent gained weight after two years. Another study followed 149 kids with celiac disease who went on a gluten-free diet for at least 12 months; in this case, the percentage of overweight children nearly doubled.

This weight gain may, in part, be attributable to people substituting regular pastas and breads for gluten-free versions and thinking them healthier. But these gluten-free alternatives are sometimes less healthy than the regular versions. As an article Linda Geddes in New Scientist noted: "A team in Spain recently examined the daily diets of 58 people with celiac disease and found that, in general, they contained more fat and less fibre than those of people who do eat gluten."

Similarly, as Vikram Mansharamani at PBS pointed out: "A Glutino Original New York Style Bagel has 26 percent more calories, 250 percent more fat, 43 percent more sodium, 50 percent less fiber and double the sugar of a Thomas’ Plain Bagel." (The gluten-free products also cost more.)

That said, there are anecdotes about people who feel better after they cut gluten from their diet. So what's going on here? One possibility is that these folks are eating fewer processed foods, cooking at home more frequently, and eating more fruits and vegetables instead of gluten-free cookies and cakes. If so, there might be good reasons that they're feeling better that have nothing to do with gluten itself.

6) A gluten-free diet carries health risks

So there's little evidence that gluten is bad for you. But is there any evidence that gluten might be good for people? Possibly.

The diets that are known to be healthiest over the long term — like the Mediterranean diet — prominently feature fiber-rich grains. Cutting these grains may carry health risks. According to the Mayo Clinic, "People who follow a gluten-free diet may have low levels of certain vitamins and nutrients in their diets." These include iron, calcium, fiber, and folate.

"Along with fruits and vegetables, the most common sources of dietary fiber are whole-grain breads and cereals, which contain gluten," the University of Washington's gluten-free primer states. "Many people on gluten-free diets tend to eat inadequate amounts of fiber, which may lead to constipation."

Going gluten-free may also reduce the amount of beneficial bacteria in your gut, which has implications for immune system function.

7) Researchers who study gluten allergies say people should avoid going gluten-free unless it's absolutely necessary

Because of the potential harm — and unknown benefit — of recreational gluten avoidance, researchers who work in this area advise people think twice before going gluten free (unless, of course, they have celiac disease or a diagnosed allergy).

"People should avoid the self-diagnosis of gluten sensitivity since a gluten-free diet can be also responsible for negative health effects," Dr. Volta wrote in an email. This diet, he added, can "favor nutrient deficiency" and throw off the gut's microflora — especially when dieters just replace gluten-containing foods with fats and proteins. "An excessive consumption of dietary products, which are notoriously poor in fibers and vitamins, but rich in lipids and at a high caloric content, can raise metabolic abnormalities."

8) Gluten-free appears to be the latest in a long line of food fads

Science & Society Picture Library/Getty Images

Science & Society Picture Library/Getty Images

Twenty years ago, no one talked about gluten. Now it's everywhere. Gluten-free options appear on menus, in coffee shops, and in grocery stores. This is the food fad du jour, fueled by celebrities and popular books — but it didn't actually arise out of nowhere. As book author Levinovitz told Vox, we were primed to hate gluten because of the earlier anti-carb movement. When gluten-free began to gain popularity about 10 years ago, "there was already the popularity of low-carb diets for people who want to lose weight," Levinovitz explained. "The arguments against gluten hooked up with the fear of carbs."

But at a deeper level, Levinovitz thinks there is something else going on. "People saw gluten as part of a modern engineered agriculture that took us away from a paradise past associated with Paleolithic man and natural eating habits. One of the things you need for a good diet narrative is to suggest that foods you must avoid are not just high in calories but are wrong, bad. Gluten fit that narrative well."

Interestingly, people with real adverse reactions to gluten have mixed feelings about the fad. On the upside? More food options. As one Vox reader with a wheat allergy wrote in an email: "It’s my husband’s birthday today, and I got a gluten-free cake mix at the grocery store. I spent so many years unable to even taste birthday cakes, so it’s great to be able to get these items now."

Yet another Vox reader — and celiac sufferer — wrote that a side effect of the gluten-free craze "is that we're no longer taken seriously. I can tell within seconds whether or not a server in a restaurant ‘gets it.’ Typically, I get eye rolls. There are so many people who have jumped on the gluten-free band wagon, that when I dine out and ask for special precautions to be taken, I often have little confidence that the message gets to the kitchen staff."

* Update: Some readers objected to my originally citing this review article on gluten, since it was co-authored by someone with ties to the grain industry. Since that is indeed a conflict of interest, and since there are plenty of other independent scientists making the exact same points about gluten, I have removed most references to the review since it is not at all integral to this piece.

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