Individuals with Celiac disease are intolerant to gluten. However, cutting out dietary gluten is also suggested to many suffering from inflammatory bowel disease (IBD), which is often associated with Ulcerative Colitis and Crohn’s disease. On top of that, many self diagnose themselves with gluten intolerance and claim a wide range of health benefits to a gluten-free diet. A recent study has shown that for those with non-Celiac gluten sensitivity (NCGS), the gluten itself might not be to blame for GI troubles. The study comes Peter Gibson of Monash University and the results were published in the journal Gastroenterology.

The study was a follow-up to one Gibson performed in 2011. That study used 34 subjects in a double-blind randomized placebo-controlled trial. The results showed that those who had undergone a gluten free diet for 6 weeks experienced more relief from symptoms including pain, bloating, and fatigue than those who ingested controlled amounts of gluten during that same period. His conclusion at the time stated that NCGS likely existed, but there wasn’t an obvious underlying mechanism.

In this new study, Gibson utilized 37 subjects who had self-reported NCGS and IBD. Rather than just relying on subjective reports of pain, the researchers carefully monitored urine, stool, and serum samples. The diet was strictly controlled in order to rule out other nutritional variables that were not accounted for in the original study. These potential triggers included lactose, certain preservatives, and FODMAPs, which are short-chain carbohydrates which the body cannot always readily absorb.

For the first two weeks of the study, participants held a diet low in FODMAPs. Next, they cycled through diets with high-gluten, low-gluten, and a whey isolate placebo for a week each. After that, a secondary experiment was conducted with 22 of the original subjects to confirm the efficacy of the placebo. The low-FODMAP diet, high gluten diet, and the placebo diet were all consumed for three days at a time.

Ultimately, Gibson’s team discovered that following the low-FODMAP baseline diet, every other diet, including the gluten free, resulted in an increased reporting of symptoms of gas, bloating, and pain. During the second part of the experiment, the participants reported increased symptoms even while on the baseline diet. The researchers attributed this to a “nocebo” effect. This is the opposite of the placebo effect, where people take a medication with no active ingredients, but they believe they are and show signs of improvement. For a nocebo, anyone taking a substance that they perceive to be potentially harmful can actually exacerbate symptoms. The results showed that only 8% of the participants had gluten-specific effects from the diet, leading the researchers to reverse their opinion from the 2011 study and say that NCGS doesn’t really seem to be a factor in diets low in FODMAPs.

Some examples of FODMAP-containing foods include artificial sweeteners, beans, high-fructose corn syrup, and gluten-containing grains like wheat, rye, and barley. There is a great deal of overlap, thus giving up gluten invariably means cutting out a great deal of FODMAP sources as well. As the gluten sensitivity was compared against a low-FODMAP diet, future studies should seek to resolve the role FODMAPs play in intestinal irritation. This will help define the results of other studies that have found a connection between gluten and gastrointestinal distress in non-Celiac patients with IDB.