The Truth About Gluten: Understanding Sensitivity and Health

Social media and lifestyle magazines have turned gluten—a protein found in wheat, rye, barley, and to a lesser degree, oats—into a dietary villain.

Something I am eternally grateful for!

Diagnosed as a coeliac in 1961 (yes, I am the original zombie), I have lived a gluten-free life since I was three years old. I am very thankful for the paediatrician who was light years ahead of his time.

Thanks to the vilification of gluten, I can now eat and indulge in foods I thought would never be possible. HAZZARR!!

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

Our review in The Lancet01533-8/abstract) published today challenges that idea. Your gluten sensitivity might be something else entirely.

Symptoms but Not Coeliac

Coeliac disease occurs when the body’s immune system attacks itself after someone eats gluten. This leads to inflammation and damage to the gut. However, people with gut or other symptoms after eating 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. 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 certain fruits, vegetables, legumes, and cereals, their symptoms improved—even when gluten was reintroduced.

Another study found that fructans—a type of FODMAP in wheat, onion, garlic, and other foods—caused more bloating and discomfort than gluten itself.

This suggests that 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.

The Role of Expectation

A consistent finding is how expecting to have symptoms profoundly shapes people’s experiences. This is a significant conversation in healthcare and the power of the mind.

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 perception of 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.

Why Do People Feel Better on a Gluten-Free Diet?

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

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. However, 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 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.

This blog was reproduced from an article in The Conversation. You can view the original article by clicking on the link below: