Challenging the Gluten-Free Movement

Oats, barley, and some products made from them Photographer: Peggy GrebThe gluten-free movement is rising. According to a 2013 consumer survey, over 70 million American adults are trying to eat less gluten, a grain-based protein. That’s a 20% boost in recruits since 2010. By 2016, sales of gluten-free foods could hit $15 billion, a 40% increase over 2013.

Yet only an estimated 2o million Americans of all ages suffer from gluten intolerance. Around 2 million have celiac disease and another 18 million may have non-celiac gluten sensitivity.

So at least 50 million people are spending billions of dollars to avoid eating a protein that probably isn’t bad for them. Why? Does a gluten-free diet still benefit those who aren’t gluten intolerant? Is gluten intolerance more prevalent than experts believe? The answers don’t look good for the movement.


Most people can eat healthy without the gluten-free fuss

A gluten-free diet is a treatment for disease. If you have celiac disease, gluten damages your small intestine. It also causes fatigue, gastrointestinal distress, and around 300 other potential symptoms. If you have non-celiac gluten sensitivity, intestinal issues are less severe; problems outside the gut, such as joint pain and “foggy mind,” tend to be a bigger complaint. Either way, we’ll say you’re gluten intolerant—a label also used for the wheat allergic—which means you give up gluten so you don’t get sick.

Most of us (likely 90% or more) have no reason to avoid gluten. There’s no scientific evidence that gluten is bad for people who aren’t gluten intolerant. Granted, some gluten-rich foods are unhealthy. In South Park’s sendup of the gluten-free movement, pizza, cake, and other glutenous delights dissolve your flesh and, if you’re male, blast off your genitals. (The show somewhat exaggerates gluten’s ill effects.) Go gluten-free and, yes, junk foods made with the grain-based protein will drop off your plate.

But if you’re not gluten intolerant, the gluten in those foods doesn’t threaten your health. Saturated fat, refined sugar, excess salt and cholesterol—these pose the dietary danger, as most American consumers are aware. For instance, 80% know that saturated fat is linked to heart disease and sugary drinks can lead to weight gain.

Public understanding of gluten’s health effects looks to be lacking. 75% of U.S. consumers who don’t think they’re gluten intolerant yet eat gluten-free say they do it because they believe gluten-free foods are healthier. Over 25% say they do it because they believe gluten-free foods promote weight loss. Although naturally healthy and slimming foods such as fruits, vegetables, and “super grains” lack gluten and likely offer the benefits gluten-free eaters tout, popular gluten-free products can have more calories and fewer nutrients (for a higher price) than the foods they replace.

People self-diagnosed as gluten intolerant can easily be wrong

What if you do think you’re gluten intolerant? Seek a professional diagnosis. Celiac disease doubled in prevalence over the past 20 years, and most of the 2 million (or more) who have it remain undiagnosed. Millions more may have non-celiac gluten sensitivity. But the rate of gluten intolerance likely isn’t as high as the booming gluten-free market suggests. Dubious self-diagnoses abound.

A professional diagnosis goes basically like this. Blood tests and other screenings check for celiac disease and wheat allergy. Non-celiac gluten sensitivity has no biological markers, so diagnosing it comes down to ruling out at least celiac disease and seeing whether symptoms improve on a gluten-free diet. However, if you tell your doctor that you’re gluten-free and feeling great prior to a medical evaluation for gluten intolerance, your doctor will probably make you eat gluten.

At first blush, a DIY diagnosis of gluten intolerance doesn’t look to be inaccurate—just imprecise. According to the self-diagnosed, eating gluten makes them feel bad and avoiding it makes them feel better. Without lab work, they can’t pin down which type of gluten intolerance they do or don’t have. But can’t they safely say they have some type, even if it’s just non-celiac gluten sensitivity?

No, they can’t.

Carbohydrates called FODMAPs may be the real problem

Wheat, barley, and rye—three prime sources of gluten—contain fructans, a fructose-based FODMAP. A small study out of Monash University got some big press (NPR, Forbes) for suggesting that FODMAPs lie behind the symptoms of non-celiac gluten sensitivity.

The double-blind, placebo-controlled study included 37 participants. None had celiac disease. All had Irritable Bowel Syndrome (IBS) and all reported being gluten sensitive. Yet only 8% were found to suffer gluten-specific effects. What’s more, all 37 saw their symptoms improve on a low-FODMAP diet.

Or the problem may not be real at all

The hot headline from the Monash study wasn’t “Gluten Sensitive May Just Need To Watch Carbs.” It was more like “Gluten Sensitive Likely Delusional” (PBS Nova). In addition to the results about FODMAPs, the study found subjects felt worse even when their diet was gluten-free. A nocebo effect was at work.

The researchers ran two experiments. First, 37 subjects took part in 7-day trials. Later, 22 of the 37 came back to do 3-day trials. Here’s the stage-by-stage timeline for both experiments.

  1. Baseline (1 week) Usual, pre-study diet
  2. Run-in (2 weeks) Diet that’s gluten-free and low-FODMAP
  3. Trial (7 or 3 days) Run-in diet plus either
    1. High-gluten 16g gluten
    2. Low-gluten 2g gluten and 14g whey
    3. Placebo 16g whey (7-day) or no change (3-day)
  4. Wash-out (≥2 weeks or ≥3 days) Run-in diet until any symptoms subside followed by new Trial

Symptoms improved on the run-in diet compared to baseline. The three trial diets were eaten in random order. Compared to run-in, symptoms worsened whether the trial added gluten, whey, or nothing at all. Subjects responded the most to whichever trial diet came first. These results suggest the subjects’ symptoms originated in their minds, not their diets.

The Monash study has its limitations. For instance, the sample size is small. But an Italian study with over 900 participants also casts doubt on self-reports of gluten intolerance: 70% (644 of 920) in that study were mistaken. Besides, much of the research on non-celiac gluten sensitivity has “significant methodological flaws, including small sample size, a lack of adequate controls, a lack of blinding, and the use of nonvalidated outcome measures,” according to a review in Gastroenterology. The Monash study, to its credit, was double-blind and placebo-controlled (as was the Italian study).1

But go back to the Gastroenterology quote. The science of non-celiac gluten sensitivity sounds shaky. In a February 2014 interview with Scientific American, the Director of Gastroenterology Research at UC San Diego, Sheila Crowe, invoked the story of the blind men and the elephant to describe the current state of research. Her point, I take it, is that a complete, coherent explanation of non-celiac gluten sensitivity has yet to emerge. So a decisive scientific victory still eludes debunkers and defenders alike. However, as the Gastroenterology review also said, the condition’s lack of biological markers leaves it “shrouded in skepticism and confusion.” And its link to nocebo responses in the Monash Study isn’t helping.

In any case, the evidence that going gluten-free helps you get healthy and trim just isn’t there. These people don’t know what they’re talking about.

Notes:

  1. I can’t speak to the validity of the outcome measures in the Monash study (nor the Italian study). Symptoms were reported using a Visual Analogue Scale (VAS). A Daily Fatigue Impact Scale (D-FIS) was also used. Various biological markers were recorded as well.