Social media and lifestyle magazines have turned gluten – a protein in wheat, rye and barley – into a dietary villain.

Athletes and celebrities have promoted gluten-free eating as the secret to better health and performance.

But our review in The Lancet published today challenges that idea.

By examining decades of research, we found that for most people who think they react to gluten, gluten itself is rarely the cause.

Symptoms but not coeliac

Coeliac disease is when the body’s immune system attacks itself when someone eats gluten, leading to inflammation and damage to the gut.

But people with gut or other symptoms after eating foods containing gluten can test negative for coeliac disease or wheat allergy. They are said to have non-coeliac gluten sensitivity.

We wanted to understand whether gluten itself, or other factors, truly cause their symptoms.

What we did and what we found

Our study combined more than 58 studies covering symptom changes and possible ways they could arise. These included studying the immune system, gut barrier, microbes in the gut, and psychological explanations.

Across studies, gluten-specific reactions were uncommon and, when they occurred, changes in symptoms were usually small. Many participants who believed they were “gluten sensitive” reacted equally – or more strongly – to a placebo.

One landmark trial looked at the role of fermentable carbohydrates (known as FODMAPs) in people who said they were sensitive to gluten (but didn’t have coeliac disease). When people ate a low-FODMAP diet – avoiding foods such as certain fruits, vegetables, legumes and cereals – their symptoms improved, even when gluten was reintroduced.

Another showed fructans – a type of FODMAP in wheat, onion, garlic and other foods – caused more bloating and discomfort than gluten itself.

This suggests most people who feel unwell after eating gluten are sensitive to something else. This could be FODMAPs such as fructans, or other wheat proteins. Another explanation could be that symptoms reflect a disorder in how the gut interacts with the brain, similar to irritable bowel syndrome.

Some people may be truly sensitive to gluten. However, current evidence suggests this is uncommon.

People expected symptoms

A consistent finding is how expecting to have symptoms profoundly shapes people’s symptoms.

In blinded trials, when people unknowingly ate gluten or placebo, symptom differences almost vanished.

Some who expected gluten to make them unwell developed identical discomfort when exposed to a placebo.

This nocebo effect – the negative counterpart of placebo – shows that belief and prior experience influence how the brain processes signals from the gut.

Brain-imaging research supports this, showing that expectation and emotion activate brain regions involved in pain and how we perceive threats. This can heighten sensitivity to normal gut sensations.

These are real physiological responses. What the evidence is telling us is that focusing attention on the gut, coupled with anxiety about symptoms or repeated negative experiences with food, has real effects. This can sensitise how the gut interacts with the brain (known as the gut–brain axis) so normal digestive sensations are felt as pain or urgency.

Recognising this psychological contribution doesn’t mean symptoms are imagined. When the brain predicts a meal may cause harm, gut sensory pathways amplify every cramp or sensation of discomfort, creating genuine distress.

This helps explain why people remain convinced gluten is to blame even when blinded studies show otherwise. Symptoms are real, but the mechanism is often driven by expectation rather than gluten.

So what else could explain why some people feel better after going gluten-free? Such a change in the diet also reduces high-FODMAP foods and ultra-processed products, encourages mindful eating and offers a sense of control. All these can improve our wellbeing.

People also tend to eat more naturally gluten-free, nutrient-dense foods such as fruits, vegetables, legumes and nuts, which may further support gut health.

The cost of going gluten-free

For the approximately 1% of the population with coeliac disease, avoiding gluten for life is essential.

But for most who feel better gluten-free, gluten is unlikely to be the true problem.

There’s also a cost to going gluten-free unnecessarily. Gluten-free foods are, on average, 139% more expensive than standard ones. They are also often lower in fibre and key nutrients.

Avoiding gluten long term can also reduce diversity in your diet, alter your gut microbes and reinforce anxiety about eating.

Is it worth getting tested?

Unlike coeliac disease or a wheat allergy, non-coeliac gluten sensitivity has no biomarker – there’s no blood test or tissue marker that can confirm it.

Diagnosis instead relies on excluding other conditions and structured dietary testing.

Based on our review, we recommend clinicians:

• rule out coeliac disease and wheat allergy first
• optimise the quality of someone’s overall diet
• trial a low-FODMAP diet if symptoms persist
• only then, consider a four to six-week dietitian-supervised gluten-free trial, followed by a structured re-introduction of gluten-containing foods to see whether gluten truly causes symptoms.

This approach keeps restriction targeted and temporary, avoiding unnecessary long-term exclusion of gluten.

If gluten doesn’t explain someone’s symptoms, combining dietary guidance with psychological support often works best. That’s because expectation, stress and emotion influence our symptoms. Cognitive-behavioural or exposure-based therapies can reduce food-related fear and help people safely reintroduce foods they once avoided.

This integrated model moves beyond the simplistic “gluten is bad” narrative toward personalised, evidence-based gut–brain care.

Jessica Biesiekierski, Associate Professor of Human Nutrition, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.