Gluten isn't as bad as it seems. New research from scientists.

Despite patient concerns, many cases of irritable bowel syndrome (IBS) may not actually be related to gluten, researchers report in The Lancet Gastroenterology & Hepatology.

Irritable bowel syndrome (IBS) is one of the most common functional bowel disorders - almost 4% of people worldwide suffer from it, with the incidence rate varying between continents and countries, ranging from 1 to 25%.

It is a chronic, functional disease of the gastrointestinal tract. Recurrent intestinal dysfunction and hyperreactivity are not associated with organic or biochemical changes in the body. According to experts, despite the bothersome symptoms (abdominal pain, bloating, diarrhea, and constipation), many cases remain undiagnosed because patients often do not seek medical help.

The mechanism of IBS is unknown, but many people with the condition believe that their symptoms are made worse by consuming gluten, found in wheat, barley, and rye.

Premysl Bercik from McMaster University in Canada and his colleagues studied 28 people with IBS who reported improvement after following a gluten-free diet.

The researchers asked participants to follow a gluten-free diet for three weeks, after which they rated the severity of their symptoms on a scale of 0 to 500, with an average score of 183.

They then randomly assigned participants to eat one of three types of cereal bars each day, each of which looked and tasted the same. One bar contained wheat, the second contained only gluten (without other wheat ingredients), and the third was free of both. The gluten dose in the first two bars was equivalent to four slices of bread. Participants were told that the bars could worsen their symptoms, but they were not informed which ingredients contained which. One week later, participants rated the severity of their symptoms and then returned to a gluten-free diet for two weeks to reverse the effects of the bars.

The experiment was repeated twice more so that each participant ate all three types of bars.

After the gluten-free bars, eight participants reported a 50-point worsening of their symptoms—a level of change that doctors consider significant. Ten participants also experienced a worsening after consuming only gluten-free bars and 11 after consuming wheat bars.

While gluten and wheat are likely real triggers for symptoms in some people with IBS, Bercik said the results suggest that others are influenced by the nocebo effect —the expectation of worsening symptoms actually causing them to occur.

Stool samples collected from participants also showed that some did not eat the bars as instructed. This may indicate that they did not consume enough gluten or wheat for these ingredients to significantly affect their gut.