Fructan Carbs, Not Gluten, May Actually Be the Cause of Gut Issues

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Perhaps gluten has been miscast as the stomach-pain-causing-culprit the whole time. A new study suggests that a separate substance – a class of sugars called fructans – is linked to the digestive distress that is similar in nature to the symptoms of celiac disease.

Fructans, a type of sugar chain, are commonly found in foods that also contain gluten, such as bread, pasta, barley and couscous, as well as onions, garlic, cabbage and beans, note the researchers, who published their findings in the journal Gastroenterology.

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Because many people who went on a gluten-free diet avoided foods also containing fructans, the researchers speculate that those people experienced something of a false positive when they saw improvement.

“Gluten was originally assumed to be the culprit because of celiac disease, and the fact that people felt better when they stopped eating wheat,” Peter Gibson, a researcher at Monash University in Australia, told New Scientist. “Now it seems like that initial assumption was wrong.”

It remains possible that some people do have a true sensitivity to gluten, although studies have not been able to ascertain how, note the researchers. “But certainly the evidence points to fructans being more of a problem,” said Gibson.

For the current study, the researchers assessed 59 non-celiac adults who had been on a gluten-free diet. Over the course of several weeks, the study participants consumed three different kinds of cereal bars – one containing gluten, one with fructans and one with neither substance.

Related: Gluten-Free Foods Might Cause Weight Gain

Compared to the control bar, the fructan-containing bar resulted in significantly more gastrointestinal distress among study participants, including a 15 percent increase in bloating and a 13 percent rise in overall symptoms. The bars containing gluten, meanwhile, had no reported effects.

The researchers speculate that the science behind the new findings suggest why those who cut gluten from their diets don’t experience a full remission of symptoms – the root cause of their distress, i.e., fructans, are still part of their diet.

Adding to the Evidence

The new study follows other reports pointing to fructans as a source of celiac-like symptoms. For example, a 2014 study found that “dietary fructose and fructan intolerance are common clinical problems that lead to unexplained GI symptoms.” But the study also noted: “Fructan intolerance is a new concept and warrants further studies.”

The evidence appears to be growing. The researchers of the current study point to a recent bout of clinical trials showing that roughly seven out of 10 people with irritable bowel syndrome show improved symptoms when they eliminate fructans and a type of food known as FODMAPs from their diet.

Related: Too Little Gluten May Increase Risk of Type 2 Diabetes

FODMAPs, or fermentable oligosaccharides, disaccharides, monosaccharides and polyols, are “short-chain carbohydrates which are poorly absorbed in the GI tract,” according to the authors of the 2014 paper. You can find a more complete list of high-FODMAP foods in their study.

Many medical professionals are starting to put their patients on a FODMAP-free diet.

“Once coeliac disease has been ruled out, I still recommend knocking off wheat to see if that helps, but I explain that it’s to eliminate fructans not gluten from their diet,” Katie Ellard, a gastroenterologist at Mater Hospital in Sydney, Australia, told New Scientist.

Richard Scott

Richard Scott is a health care reporter focusing on health policy and public health. Richard keeps tabs on national health trends from his Philadelphia location and is an active member of the Association of Health Care Journalists.