Researchers at the Celiac Disease Center at Columbia University Medical Center (CUMC) have reported that they have found traces of gluten in over half of the popular probiotics they tested.

They performed the tests on 22 top-selling probiotics, and revealed that 12 of them had detectable amounts of gluten.

Patients generally take probiotics for their theoretical effect in promoting intestinal health, though its evidence of benefits is limited to a few clinical situations.

Dr. Samantha Nazareth, a gastroenterologist at CUMC and the first author of the study, said that a lot of patients with celiac disease take dietary supplements, and that probiotics are particularly popular. Nazareth added that they have previously reported that celiac patients who use dietary supplements have more symptoms as compared to non-users, due to which they decided to test the probiotics for gluten contamination.

Gluten is a protein in grains like wheat, rye, and barley, but in recent years it has become trendy to exclude it from the diet. People with celiac disease really need to avoid it because if they don’t then they could encounter pain and gastric distress. There is some evidence that has raised their cancer risks.

It's noteworthy that the majority of the probiotics that tested positive for gluten had really small amounts less than 20 parts per million of the protein. In fact, such an amount would be considered gluten-free by Food and Drug Administration (FDA) standards.

Researchers said that however four of the brands, 18% of the total, contained in excess of that amount. They mentioned that two of them had a label that declared them to be ‘gluten free’.

Dr. Peter Green, professor of medicine and director of the Celiac Disease Center, said, “We have been following reports in the scientific literature and news media on inaccurate labeling of nutritional supplements, and it appears that labels claiming a product is gluten-free are not to be trusted, at least when it comes to probiotics”. He mentioned that they are concerned as this is a potential hazard for the patients.

However, the researchers have conceded that it isn't clear yet if these trace amounts of gluten are enough to cause harm to someone with celiac disease or not.