Wellness, Actually · August 6, 2026
Is gluten actually bad for you?
Short answer
For most people, no. Celiac disease is real, affects about 1% of the US population, and is diagnosed with a blood test that is roughly 95% sensitive and specific plus a confirmatory biopsy. But of the roughly 10% of people worldwide who self-identify as gluten sensitive, only 16% to 30% have symptoms reliably reproduced in blinded challenges, and one randomized trial found fructans in wheat, not gluten, drove the bloating. Get tested for celiac first; if that's negative, work with a dietitian rather than cutting out bread and hoping.
About 30% of Americans say they limit their gluten intake. Roughly 1% actually have celiac disease. That gap is where an entire industry lives, and it's also where a lot of people stop looking for the real reason they feel bad.
Gluten is a protein. Two proteins, really: gliadin and glutenin. It's the main protein in wheat, and it's also in barley and rye. It's the stuff that polymerizes when you work dough, the reason pizza dough springs back when you roll it, the reason the carbon dioxide from the yeast gets trapped in bread instead of escaping. No other grain does this. That's why rice flour gives you a sad, crumbly loaf unless you add guar gum or xanthan gum to fake the structure. Gluten also turns up where you don't expect it: soy sauce, a lot of salad dressings, malt vinegar.
The gluten diseases that are unambiguously real
Celiac disease has been described for something like 1,700 years. The oldest reference I found is from 300 AD. The name literally means "belly" in Greek, which tells you how much the ancients understood about it.
In kids it typically shows up as GI symptoms, malnutrition, and failure to thrive, and for a long time it was thought of as a pediatric disease. We now know it can present in adulthood. It's also a great imitator. Yes, diarrhea and gas and bloating. But also joint pain, fatigue, anemia, osteoporosis, and a characteristic intensely itchy vesicular rash called dermatitis herpetiformis on the extensor surfaces of the arms and legs. Anemia is common. Fatigue is common. Rashes are common. Your doctor has to think of it.
Once they do, it's straightforward. The screening test is an anti-tissue transglutaminase antibody, about 95% sensitive and specific, with a confirmatory endoscopic biopsy. And a strict gluten-free diet is genuinely curative, as long as you stay on it. For real celiac, a tiny amount of gluten sets it off. Despite all of that, the average gap between first symptoms and diagnosis runs about 11 years.
The environmental trigger wasn't identified until World War II. A Dutch pediatrician, Willem-Karel Dicke, noticed his patients improved during the Dutch hunger winter of 1944-45 when bread ran out, and relapsed when the Allies airdropped supplies and they started eating bread again. Two millennia of describing the disease, and it took a famine to find the cause.
Celiac is genuinely getting more common, and not just because we're looking harder. A 2009 study in Gastroenterology went back to blood samples banked at Warren Air Force Base from young servicemen in 1948 and 1954 and tested them for the anti-tTG antibody. Some of those men had it and almost certainly were never diagnosed. Compared with modern rates, the antibody is several times more common today. Fifty years is nowhere near enough time for genetic drift, so something in the environment changed.
One hypothesis involves how we make bread. Traditional slow fermentation, the 24- to 36-hour sourdough approach, gives yeast and bacteria time to partially break down the gliadin and glutenin, potentially into a less immunogenic form, and a small study of 17 people suggests sourdough may be a bit gentler. Modern industrial bread uses the Chorleywood process, which gets you from flour to finished loaf in about two hours using much more yeast and mixing so intense they have to inject cold water to keep the dough from overheating. The yeast never get time to do their protein work. It's a reasonable story. It's also speculation. Autoimmune disease in general has been climbing, and you can't blame bread for all of it.
Two other conditions belong here. Wheat allergy is a conventional food allergy, distinct from celiac, presenting with the usual allergy picture up to and including anaphylaxis. There's a strange variant, wheat-dependent exercise-induced anaphylaxis, where eating wheat is fine and exercising is fine, but doing both in close proximity triggers anaphylaxis. And there was the Cha No Shizuku episode in Japan, where a facial soap containing hydrolyzed wheat protein caused several thousand women to develop wheat anaphylaxis. Eating an allergen tends to be protective, the way early peanut exposure is. Getting it through your skin or lungs is a different story. Then there's gluten ataxia, an autoimmune condition related to celiac that attacks the brain rather than the small intestine. It is rare.
Non-celiac gluten sensitivity: real, but smaller than you think
This is what most people avoiding gluten believe they have. About 10% of people worldwide self-identify as gluten sensitive.
There's no case definition, no biomarker, no blood test, and no evidence of immune activation like the immunoglobulins we can find in celiac. What people report is bloating, diarrhea, sometimes constipation, plus brain fog, fatigue, and low mood. Which makes skeptics roll their eyes, because everyone gets gassy sometimes.
The useful evidence comes from blinded challenges. Instead of telling someone to go gluten-free and asking how they feel, which invites a large placebo effect, you give them food that either contains gluten or doesn't, and they don't know which. Among people who believe they're gluten sensitive, 16% to 30% have their symptoms reliably reproduced. So something real is happening in a meaningful minority, even if we can't see it in the blood. And roughly 70% don't react to gluten at all.
Some of what's left is expectation. In nocebo work, researchers crossed two things: what people were told they were getting, and what they were actually given. People told they were getting gluten had significantly more GI symptoms than people given gluten and told they weren't. And people told they were getting gluten who received none looked like the people who got the real thing. Expectation mattered more than the flour.
That's not a knock on anyone. Your brain talks to your gut constantly and can make your intestines do things. You've experienced this yourself, the moment you get within sight of a bathroom you actually want to use. Expectation producing real GI symptoms is just how the plumbing works.
It might be the wheat without being the gluten
Gluten travels in company. The most important companions are fructans, chains of fructose molecules that humans lack the enzymes to digest. Your colonic bacteria digest them happily and produce gas and bloating in the process. The main source of fructans in the Western diet is wheat.
Cut out gluten and you cut out wheat, and you cut out fructans by proxy. You may feel better. The gluten may have had nothing to do with it. A 2018 randomized trial in Gastroenterology put 59 people already on a gluten-free diet for suspected sensitivity onto muesli bars containing gluten, fructans, or neither for a week at a time. Symptom scores were significantly higher on fructans than on gluten. If fructans are your problem, a low-FODMAP diet is a more targeted answer than eliminating gluten forever.
People also blame the wheat itself. A 2024 crossover trial in the American Journal of Clinical Nutrition compared "ancient" wheat cultivars with modern ones and found no difference in GI symptoms. Organic wheat has gluten too, in the same amounts.
And then there's Europe. Everyone has a friend who says their gluten problem vanishes in Paris. Croissants have gluten. Someone with celiac who eats a French croissant will feel exactly as bad as they would eating an American one, and the epidemiology of both celiac and self-reported gluten sensitivity is about the same on both continents. Something else is going on in that vacation, and it isn't magic French wheat.
What going gluten-free actually costs you
Gluten-free substitutes sit further along the ultra-processed spectrum. They tend to be lower in fiber and folate, higher in fat and sugar, and two to three times the price. There's also a 2017 paper in Epidemiology on the unintended consequences of a gluten-free diet that found higher urinary arsenic and mercury in people avoiding gluten, because rice flour carries more of both than wheat flour does.
You also don't get an athletic edge. I looked, mostly so I could inflict a gluten-free decade on my co-host. A 2015 crossover trial in Medicine and Science in Sports and Exercise randomized 13 endurance cyclists to gluten-containing and gluten-free diets, calorically matched, and ran time trials. No difference in speed. No difference in endurance.
The larger cost is diagnostic. Someone feels bloated and foggy and tired, an influencer tells them it's gluten, they switch to cottage cheese tortillas, and they feel better for a while because taking action has its own placebo effect. Then the symptoms creep back, because the actual problem was fiber, or hydration, or alcohol, or fructans, or something no one has looked for yet. Now they're a year down the road, spending triple on bread, and no closer to an answer.
Bottom line
If you have persistent GI symptoms, fatigue, anemia, or that itchy rash, get tested for celiac disease before you change your diet. Going gluten-free first makes the test harder to interpret, and you want to know. If the test is negative, the next step is a dietitian and the unglamorous work of structured food trials and symptom logs, not a blanket ban on wheat. Roughly a third of people who think they're gluten sensitive actually react to gluten under blinding, which means most people avoiding it are treating the wrong thing. Figuring out which group you're in is worth the effort, because a life without pasta and bread is a measurably less happy one.
Here's our discussion from the episode:
I covered this in depth on Wellness, Actually, listen below.
Frequently asked questions
How do you get tested for celiac disease?
The screening test is a blood test for anti-tissue transglutaminase antibodies, which is about 95% sensitive and specific. A positive result is usually confirmed with an endoscopic biopsy of the small intestine. Get tested before going gluten-free, since removing gluten first makes the results harder to interpret.
What is the difference between celiac disease and gluten sensitivity?
Celiac disease is an autoimmune condition with a genetic basis and an environmental trigger, and it can be confirmed with a blood test and biopsy. Non-celiac gluten sensitivity has no case definition, no biomarker, no blood test, and no sign of immune activation. Only 16% to 30% of people who self-identify as gluten sensitive have their symptoms reproduced in blinded challenges.
Can gluten sensitivity actually be caused by something else in wheat?
Often, yes. Wheat is the main source of fructans in the Western diet, chains of sugar molecules humans cannot digest but colonic bacteria can, producing gas and bloating. A 2018 randomized trial in Gastroenterology gave 59 people muesli bars with gluten, fructans, or neither, and symptom scores were significantly higher on fructans than on gluten. A low-FODMAP diet targets fructans without eliminating all gluten.
Is sourdough bread easier to digest than regular bread?
Possibly, but the evidence is thin. Slow fermentation over 24 to 36 hours gives yeast and bacteria time to partially break down gliadin and glutenin into a potentially less immunogenic form, and one small study of 17 people suggests sourdough may be somewhat better. Modern industrial bread made by the Chorleywood process goes from flour to loaf in about two hours, leaving no time for that breakdown. For someone with actual celiac disease, sourdough is not safe.
Is a gluten-free diet healthier if you don't have celiac disease?
Generally not. Gluten-free packaged foods tend to be more processed, lower in fiber and folate, higher in fat and sugar, and two to three times the price. A 2017 paper in Epidemiology also found higher urinary arsenic and mercury levels among people on gluten-free diets, because rice flour carries more of both than wheat flour.
Does cutting out gluten improve athletic performance?
No. A 2015 randomized crossover trial in Medicine and Science in Sports and Exercise put 13 endurance cyclists on gluten-containing and gluten-free diets that were calorically matched, then ran time trials. There was no difference in speed or endurance either way.
Why do people say they can eat bread in Europe but not in the US?
There is no good evidence that European wheat is different in a way that matters. Croissants contain gluten, and someone with celiac disease will react to a French croissant the same way they react to an American one. The epidemiology of both celiac disease and self-reported gluten sensitivity is about the same in Europe and the US, so the explanation is more likely something else about the food environment or the trip itself.
Wellness, Actually Podcast
"What's the deal with gluten?" — Listen to the full episode, including the week's health news and listener Q&A.
About the author
F. Perry Wilson, MD MSCE is a nephrologist, clinical researcher, and Associate Professor of Medicine and Public Health at Yale University, where he directs the Clinical and Translational Research Accelerator. He hosts the Wellness, Actually podcast with Emily Oster, writes the weekly Impact Factor column on Medscape, and is the author of How Medicine Works and When It Doesn't (Grand Central, 2023).