Celiac disease is a relatively uncommon condition that affects 1-2 percent of Europeans and less than 1 percent of Americans. Left untreated, it can lead to a range of digestive issues and cause damage to the small intestine. We know some people have a genetic predisposition to the disease, with environmental factors acting as triggers, but we still don’t know exactly what’s going on. Now, scientists have identified certain bacteria as potential culprits, explaining how these tiny microbes can spark the disease.

People with celiac disease can’t tolerate gluten, the proteins found in cereal grains like wheat and barley. Their immune system wrongly identifies gluten as a threat, producing an inflammatory response in the small intestine. This in turn can lead to stomach pains, bloating, diarrhea, fatigue, and iron-deficiency anemia, among other symptoms. So, it’s vital that celiacs avoid eating gluten entirely – that means no conventional bread, cakes, or pastries. Even beer contains gluten.

So how might bacteria lead to this strange condition? A team of Australian scientists recently isolated receptors from the T cells (a kind of immune cell) of celiac patients and discovered that they could recognize protein fragments from certain bacteria. When our immune system comes into contact with a pathogen, like a bacterium, it commits it to memory in case it ever invades the body again. What’s so interesting about the bacterial protein fragments that the researchers looked at, however, is that they mimic the protein fragments in gluten.

So, what’s likely happening is that some people who have the right genetics to develop celiac disease come into contact with bacteria containing proteins that mimic gluten. Then, when gluten enters their body, their immune system mistakes the gluten for these potentially harmful bacteria, and produces a response that upsets the person’s digestive system. The findings are reported in Nature Structural and Molecular Biology.

“We have provided a proof-of-principle that there's a link between gluten proteins and proteins that are found in some bacteria," said Dr Hugh Reid of Monash University in a statement.

"That is, it's possible that the immune system reacts to the bacterial proteins in a normal immune response and in so doing develops a reaction to gluten proteins because, to the immune system, they look indistinguishable – like a mimic."

While it’s still early days, and not all cases of celiac disease are necessarily connected to bacteria, the researchers hope their findings might contribute towards better diagnostic techniques and treatments for the condition in the future. Early diagnosis is essential as untreated celiac disease can wreak havoc on the small intestine and damage a person’s health, so if you think you may be a sufferer, see your healthcare provider.