Think you’re gluten intolerant? You might not be

Not all patients with irritable bowel syndrome may be sensitive to gluten, despite numerous studies identifying it as a potential trigger. 

According to new research, patients with IBS who have been led to believe that gluten—the protein in wheat products like bread and pasta—triggers their symptoms may have been misled. 

According to Canadian researchers, too many IBS patients are restricting themselves to different diets to avoid perceived food triggers—despite not having clearly identified which foods actually worsen their symptoms.

In the study, researchers analysed 28 participants with IBS from McMaster University Digestive Disease clinic, who believed they had a gluten intolerance and as such followed a strict gluten-free diet. 

Participants were given cereal bars to eat everyday for a week—made from either purified gluten, whole wheat or gluten-free flour—without knowing which was which. 

After completing a week eating one type of cereal bar participants had a two-week break before starting on the next bar, until all three had been trialled. 

Researchers found that there was no significant difference in the worsening of symptoms between the three groups, including the gluten-free placebo. 

They noted that even after eating the gluten-free control cereal bar, nearly 30 per cent of patients experienced a 50-point worsening of symptoms according to the IBS symptom severity scale. 

Professor Premysl Bercik, senior author of the study, concluded: ‘Some patients truly have a sensitivity to this food protein, but for many others, it’s the belief itself that’s driving their symptoms and subsequent choices to avoid gluten-containing foods’.

Despite this, even when participants were informed of the results, most continued to believe that gluten and wheat trigger their symptoms and continued to eat a gluten-free diet. 

This in turn could perpetuate symptoms of IBS, leading to malnutrition and lower quality of life, Prof Berick warned. 

This is because gluten-free foods typically contain more fat, salt and sugar and less gut-friendly fibre and protein than their equivalents.  

Writing in the journal Lancet Gastroenterology and Hepatology, researchers advised that psychological counselling should be incorporated into treatment plans for patients suffering with IBS. 

‘What we need to improve our clinical management of these patients is to work with them further, not just tell them that gluten is not the trigger and move on. 

‘Many of them may benefit from psychological support and guidance to help destigmatise gluten and wheat and reintroduce them safely in their diet,’ Prof Bercik added. 

The researchers added that social media could be behind the trend, with many influencers sharing how eating gluten worsened their symptoms. 

But for others, Prof Berick said avoiding gluten could be a coping mechanism. 

‘Continuing the gluten-free diet might have provided patients with an actionable method to try to control their symptoms, despite the risk of unnecessary diet restrictions.’

 Professor Sigrid Elsenbruch, an expert in neurological and behavioral sciences who was not involved in the study, added: ‘Changing health-related behaviours is notoriously challenging. 

‘Persistent dietary choices might reflect the complexity of IBS symptom management rather than an unwillingness to adjust beliefs.’  

The researchers of the current study concluded that their findings support the role of psychological factors in symptom responses and  dietary behaviours in IBS. 

But common limitations of diet studies were observed with lab tests indicating that only around a third of participants followed the gluten-free diet as instructed, and some may have skipped bars altogether to avoid symptoms. 

IBS is a common debilitating condition that affects the digestive symptom, causing agonising stomach cramps, bloating, diarrhoea and constipation—with few effective treatments available. 

Over time, damage accumulates in the gut, often leading to serious nutrient deficiencies and nerve damage. 

The long-term condition is thought to affect around 1 in 5 adults in the UK, but experts say this figure could be much higher. 

Around one in 100 people in the UK suffer coeliac disease, whereby the immune system overreacts to gluten. 

It’s thought that a further 13 per cent of people suffer what’s known as non-specific gluten sensitivity (NCGS). 

This is when eating the protein triggers unpleasant symptoms like bloating and irregular bowel habits.

Scientists aren’t yet sure the reason why some people are affected by this, and some believe it could be due to a nocebo effect — when expecting to suffer symptoms brings them on.