How can we diagnose gluten intolerance?

Many people are following a gluten-free diet under the assumption that they are intolerant; however, researchers from the University of Newcastle have found that only a small number of these people are actually sensitive to gluten or wheat.

Up to one in 100 people in Australia may have coeliac disease, but another 7% of Australians who are not diagnosed as coeliac or allergic to gluten suggest they also experience symptoms such as bloating and headaches after consuming the protein. In a study published in the Medical Journal of Australia, researchers explored whether non-coeliac gluten or wheat sensitivity (NCG/WS) could be to blame and how to diagnose this.

“It is likely that only a small proportion … are truly sensitive to gluten or wheat,” the study reported. “Many … unnecessarily subject themselves to a gluten-free diet.”

Without any biological proof, the best way to test for this sensitivity is through a “double-blind, placebo-controlled, dietary crossover challenge with gluten”. Participants did not know what they were being fed, but 40% reported bad or worse symptoms when they ate a placebo instead of gluten. The study found that only 16% had reproducible symptoms that would indicate they were NCG/WS.

Successfully diagnosing NCG/WS is important as gluten-free diets have many downfalls including an increased risk of heart attack and stroke, starving people of trace elements and vitamins, and they are 17% more expensive than a regular diet.

“When there’s this industry out there — celebrity chefs touting a gluten-free diet — people take it on as something that’s beneficial for their health. There’s very little evidence to suggest it’s good for people who don’t have coeliac disease,” said the lead author, Michael Potter.

However, co-author of the study Marjorie Walker suggested that diagnosing NCG/WS is very complex and can only really be achieved by repeatedly introducing and withdrawing gluten from the diet.

“It’s a really complex and laborious process,” she said. “A lot of people just say I feel better not eating wheat and I’m not going to do it.”

Walker continued by stating that biopsies from a subset of participants revealed cell abnormalities similar to those found in gastrointestinal disorders. With similar symptoms, many people who believe they have a gluten intolerance may actually be reacting to other compounds in wheat.

“There probably is a real ­immune action, but we haven’t quite worked out what it is they’re reacting to. It may be that the doctors haven’t quite got it right yet, rather than the patients.”