Probiotics are live bacteria and yeasts that are good for the health, especially for the digestive system. Many people commonly take probiotics for their reported effect in promoting gut health. However, a new study has revealed that more than half of popular probiotics contain traces of gluten. Gluten is a protein found in wheat, rye and barley, and patients with celiac disease need to eliminate it from their diet altogether or face pain, bowel symptoms and an increased risk of cancer.
Tests on 22 top-selling probiotics done by researchers at the Columbia University Medical Centre (CUMC) revealed that 12 of them (55%) had detectable gluten. Samantha Nazareth, gastroenterologist at CUMC and the first author of the study, said, "Many patients with celiac disease take dietary supplements and probiotics are particularly popular. We have previously reported that celiac patients who use dietary supplements have more symptoms than non-users, so we decided to test the probiotics for gluten contamination."
Most of the probiotics samples that tested positive for gluten contained less than 20 parts per million of the protein, and would be considered gluten-free by Food and Drug Administration (FDA) standards. However, four of the brands (18% of the total) contained gluten in excess of that amount. More than 50% of the 22 probiotics were labelled gluten-free but this had no bearing on whether or not traces of gluten were present. Two probiotics samples that did not meet FDA standards carried the label.
Study co-author Peter Green said, "It appears that labels claiming a product is gluten-free are not to be trusted, at least when it comes to probiotics. This is a potential hazard for our patients and we are concerned."
Study co-author Benjamin Lebwohl from CUMC said, "We know that most patients with celiac disease only develop intestinal damage when consuming more than 10 milligrams of gluten daily. Still, these findings raise troubling questions."
The study has been presented at Digestive and Disease Week in Washington DC.