PhotoPeople with celiac disease must avoid gluten in their diets and many take probiotics to aid the digestive process.

So it might come as a shock to these consumers that researchers at the Celiac Disease Center at Columbia University Medical Center (CUMC) report finding traces of gluten in more than half the popular probiotics they tested.

Tests performed on 22 top-selling probiotics revealed that 12 of them had detectable amounts of gluten.

Probiotics are commonly taken by patients for their theoretical effect in promoting intestinal health, though evidence of benefits is limited to a few clinical situations.

Supplement users have more symptoms

“Many patients with celiac disease take dietary supplements, and probiotics are particularly popular,” said Dr. Samantha Nazareth, a gastroenterologist at CUMC and the first author of the study. “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.”

Gluten is a protein in grains like wheat, rye, and barley. Even though it has become trendy in recent years to exclude it from your diet, people with celiac disease really need to avoid it. Otherwise, they could encounter pain and gastric distress. There is some evidence it raises their cancer risks.

It's important to note that the majority of the probiotics that tested positive for gluten contained really small amounts – less than 20 parts per million of the protein. In fact, they would be considered gluten-free by Food and Drug Administration (FDA) standards.

However, four of the brands – 18% of the total – contained in excess of that amount. Two of them, the researchers said, carried a label declaring them to be “gluten free.”

Inaccurate labeling

“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,” said Dr. Peter Green, professor of medicine and director of the Celiac Disease Center, “This is a potential hazard for our patients, and we are concerned.”

However, even the researchers concede it isn't clear if these trace amounts of gluten are enough to cause harm to someone with celiac disease.

"We know that most patients with celiac disease only develop intestinal damage when consuming more than 10 milligrams of gluten daily, and it is unlikely that contaminated probiotics can lead to that amount unless patients are ingesting mega-doses," said Dr. Benjamin Lebwohl, assistant professor of medicine and epidemiology at the Celiac Disease Center and a co-author of the study. Still, these findings raise troubling questions.”

For one, he asks why is there any gluten in these products at all, given that many of the people using it have no tolerance for the protein. He also wonders if other products labeled “gluten free” in fact might not be.

“And given the great consumer interest in probiotics, will regulatory bodies take action to protect the public?” he asked.

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