Walk through any grocery store and you’ll find gluten-free versions of nearly every packaged food. Recent estimates suggest 1 in 10 adults worldwide self-report gluten or wheat sensitivities. This means hundreds of millions of people are cutting gluten from their diets without a celiac disease diagnosis because they think it’s the source of their bloating, abdominal pain, or brain fog. 

While non-celiac gluten sensitivity (NCGS) is a very real condition, says Dr. Akash Goel, a top gastroenterologist and internal medicine doctor at the Atria Health Institute, the culprit can sometimes be something else entirely. When that’s the case, and people remove an entire category of food from their diet, it can lead to unintended downstream consequences, including serious micronutrient deficiencies.

That’s why Dr. Goel says it’s best to work with an expert who can help you determine which foods are causing your symptoms.

What’s celiac vs. non-celiac gluten-sensitivity?

Celiac disease causes an autoimmune response to gluten, usually confirmed through antibody testing and a small-intestine biopsy that shows damage to the villi—the finger-like projections that help the small bowel absorb nutrients. (It’s worth noting that the diagnosis criteria for celiac disease is evolving, with a 2026 review in the New England Journal of Medicine highlighting that in children, and in select adults with strongly positive blood biomarkers, biopsy may no longer be required. In countries outside the United States, the diagnostic criteria for celiac is generally less reliant on biopsy.)

Celiac disease affects 1% of the population on average, and first-degree relatives of someone with celiac have a 10-20% chance of having it themselves. Interestingly, it varies considerably based on what that relationship is! You can see a breakdown here.

NCGS is a different condition altogether in which people develop symptoms after eating gluten, despite lacking the antibodies and intestinal damage seen in celiac disease. Rather than an autoimmune disorder, it appears to reflect a more subtle mix of gut sensitivity and low-grade immune activation, though the exact mechanism isn’t fully understood.

For both celiac disease and NCGS, a strict gluten-free diet is recommended, says Dr. Goel.

When gluten might not be the culprit

If you’re not sure which foods upset your stomach, it could be a category of carbohydrates called FODMAPs (an acronym for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols), and specifically fructans. Fructans are short-chain sugars that some people have difficulty digesting. When fructans reach the gut, bacteria ferment them. For people with a sensitive gut, this fermentation can cause significant bloating and symptoms that mirror those people attribute to gluten.

Wheat contains fructans in addition to gluten. Other high-fructan foods include garlic, onions, leeks, and artichokes—so if those foods also trigger symptoms, that’s a clue that FODMAPs may be the real issue, says Dr. Goel.

When gluten is the culprit 

For those who do react to gluten, part of the problem involves a protein called zonulin, says Dr. Goel. When gluten is broken down, one of its components—gliadin—triggers the release of zonulin, which controls the tight junctions between cells lining the gut. In excess, zonulin loosens these junctions, making the intestinal barrier more permeable. That allows fragments of gliadin to slip through and activate the immune system in susceptible people. 

This process—sometimes referred to as increased intestinal permeability, or “leaky gut”—has historically been dismissed but is now increasingly recognized as real in some specific circumstances. “This model has been demonstrated in celiac disease and it’s probably true in non-celiacs as well,” says Dr. Goel.

What to do if you suspect a sensitivity

If you’re experiencing what seem like gluten-related GI symptoms, the first step is ruling out celiac disease with a doctor. This matters beyond just getting a diagnosis: untreated celiac can lead to serious micronutrient deficiencies, delayed growth in children, osteoporosis, and small bowel malignancies, among other things. Sensitivity can develop later in life, particularly in people with a family history of the disease, so it’s worth getting re-tested if your symptoms change.

If celiac is ruled out, the next step is working with a physician or registered dietitian to try gluten elimination or a structured low-FODMAP diet to help identify the real trigger. 

Dr. Goel emphasizes that a low-FODMAP diet is meant to be a temporary diagnostic tool—not a long-term eating plan. The goal is to eliminate high-FODMAP foods briefly, then reintroduce them one group at a time to identify specific triggers. Over time, most people can expand their diet again, avoiding only the foods that cause symptoms. Long-term restriction isn’t recommended, says Dr. Goel. “There are a lot of highly nutritious foods in the high FODMAP category, so it could cause nutrition deficiencies if you stayed on it too long,” he says. 

A note about the “pasta in Europe” phenomenon

Sometimes people who can’t tolerate bread or pasta at home do fine when they travel in Europe. There’s a scientific explanation for this, says Dr. Goel. In the U.S., wheat has largely been bred for quick fermentation—bread can go from mixing to baking in as little as 30 minutes or an hour. Traditionally, European bread uses longer fermentation times of 12 to 24 hours. That extended process gives yeast time to break down both the FODMAPs and the gluten in the dough, Dr. Goel explains, resulting in lower concentrations of both in the finished loaf. The wheat strains themselves also differ. The result is bread that’s considerably easier to digest—and a reminder that “gluten sensitivity” is more complicated than most labels suggest.

The bottom line

If you’ve been struggling with unexplained GI symptoms, gluten may or may not be the cause. Cutting out any food categories can have unintended consequences, so if you’re looking to change up what you’re eating, the most useful thing you can do is work with your care team to find out what’s actually behind your symptoms and what works best for you.