Non-Celiac Gluten Sensitivity: Does It Exist?

Few diets have caught fire like “going gluten-free.” One out of four households contains someone following a gluten-free diet, contributing to the $10.5 billion gluten-free food and beverage industry. But the very foundation of this expensive trend might be on shaky ground.

Gluten is a protein found in wheat, barley, rye, triticale, and some oats due to cross-contamination on farm fields. It gives foods made with these grains (like bread and pasta) their chewy texture. But gluten can also be found in many non-grain products, such as food additives, medications, and vitamins.

People who have celiac disease must follow a strict gluten-free diet. When someone with celiac disease eats gluten, her immune system responds by attacking the small intestine’s inner lining, causing symptoms ranging from gas, bloating, constipation, or diarrhea to nutrient malabsorption, unintentional weight loss, and malnutrition. An estimated 1 in 133 Americans have celiac disease, or about 1% of the population.

But many more people not diagnosed with celiac disease are removing gluten from their diets. In particular, people with irritable bowel syndrome (IBS) claim to feel better when they follow a gluten-free diet. So what gives?

A 2011 study at Monash University in Australia found that gluten was the culprit behind gastrointestinal distress among 34 participants with IBS but not celiac disease. The randomized, double-blind controlled trial essentially put the term non-celiac gluten sensitivity (NCGS) on the map, and gave rise to the concept that gluten sensitivity existed on a continuum from “not sensitive” to “very sensitive.”

But the lead scientist who conducted the 2011 study had lingering questions about the results and decided to perform another even more highly controlled trial.

In the second study, 37 participants who fit the criteria for IBS and NCGS (but were confirmed to not have celiac disease) were randomly assigned to groups given a special diet low in FODMAPs, which are known to reduce gastrointestinal symptoms in people with GI distress and IBS.

For all you chemistry buffs, FODMAP stands for “fermentable oligo-saccharides, disaccharides, mono-saccharides, and polyols,” a group of carbohydrates that are often poorly absorbed in the small intestine and, when fermented by bacteria in the gut, can cause bloating, gas, and other digestive woes. Many foods that typically contain gluten, such as foods made with wheat and rye, also contain high levels of FODMAPs.

After two weeks on the low-FODMAP diet, the study participants were placed on a high-gluten, low-gluten, or a control diet for one week. At the end of the study, only 8% of participants were found to have gluten-specific effects from the test diets but 100% experienced relief of symptoms from the low-FODMAP diet. As a result, the investigators concluded that there were no effects of gluten in patients with IBS and NCGS after controlling for FODMAPs.

So what’s a bread-lover to do? If you suspect you might be sensitive to gluten, get tested for celiac disease before you remove the gluten from your diet; you need to have some in your system in order to get an accurate result. First you’ll have a blood test that checks for the presence of specific antibodies. If the blood test comes back with a reason for further testing, the next step is to have an intestinal biopsy.

If the biopsy confirms you have celiac disease, a gluten-free diet is non-negotiable. But, if it comes back negative and you are still experiencing symptoms – and your doctor has ruled out other serious health concerns – you have two options:

  1. Based on the study above, most people feel better on a low-FODMAP diet. Learn more about starting a low-FODMAP diet here and consider working closely with a savvy physician or registered dietitian as these diets can get complex.
  2. If a low-FODMAP diet does not alleviate your symptoms, you could do a trial gluten-free diet. Be sure to strictly remove all gluten sources for a few weeks and evaluate how you feel; click here to become a gluten sleuth. If you feel markedly better, you might be truly gluten-sensitive.

As always, it’s a good idea to work with your physician and registered dietitian whenever you are experiencing troublesome symptoms or making big changes to your diet.