In the first of a multi-part Q&A series on gluten sensitivity, we go straight to the experts.
[Updated May 21, 2016]
Chances are you know someone who doesn’t have celiac disease but swears by the gluten-free diet. Maybe their migraines have eased, their skin rash has cleared or their energy level has spiked. Despite many people reporting big benefits from going gluten-free, non-celiac gluten sensitivity—gluten sensitivity, for short—is still not well understood. Some question whether it even exists. In the first installment of a series (see also Part 2 and Part 3), we ask four leading celiac experts to weigh in on the latest about gluten sensitivity.
Q: More and more people today say they’re sensitive to gluten. What’s going on?
Alessio Fasano, MD: It’s hard to answer. We’re still in the learning process about this new form of gluten reaction. After a few years of debate, we now agree that something other than celiac disease exists. What it is, how frequent it is, how to treat it and what the consequences are compared to celiac disease in terms of lack of compliance to the gluten-free diet, that’s all up in the air. With gluten sensitivity, we’re at the same crossroads that we were with celiac disease 20 years ago.
Stefano Guandalini, MD: Why gluten is so popular these days as an offending agent is hard to fully understand. Outside of celiac disease and its sister disease, dermatitis herpetiformis, we really have no solid proof that gluten is harmful for anyone else. I am rather inclined to believe that “gluten sensitivity” is an umbrella term encompassing various disorders, none of them yet well documented.
Daniel Leffler, MD: Many, many people have chronic gastrointestinal symptoms, as well as outside-the-gut symptoms, and historically not a lot of emphasis was placed on diet management for these conditions. So part of what we’re seeing is a realignment of strategies that take diet into consideration.
Cynthia Rudert, MD: We used to eat much less gluten. In the 1950s, breads and pastas were near the top (the smallest part) of the food pyramid. Now they’re at the bottom. And today’s wheat is different—it’s hybridized so the dough has a higher gluten content and is stickier. Studies show celiac disease is on the rise and that gluten sensitivity may be far more common. I never argue with someone who says they feel better off gluten.
Q: Last year, an important study from Australia called into question the existence of gluten sensitivity. A group of hard-to-digest sugars called FODMAPs, not gluten, were identified as the major culprit. Should this new study raise doubts about gluten sensitivity?
Fasano: The study targeted the wrong population. The subjects were affected by irritable bowel syndrome (IBS), not gluten sensitivity. The research team mistakenly assumed gluten sensitivity and IBS are synonymous. Unfortunately, I think all that came from this study was to further confuse the clinical and scientific community about gluten sensitivity.
Guandalini: It was a brilliant study in that it showed beyond a shadow of a doubt that at least some of the people who call themselves gluten sensitive and have IBS symptoms are actually intolerant to FODMAPs. These people showed no signs of reaction to gluten alone.
Leffler: It’s perfectly natural to expect that in a young field like gluten sensitivity, you’ll have a variety of study designs showing different things. However, if you look at the literature on the whole from the 1980s, there’s quite an impressive frequency of clinical reports of significant benefits of the gluten-free diet in patients without celiac disease. Most of us are fairly confident there is a gluten sensitivity out there but we’re not confident what’s causing it, how to diagnose it and how to study it.
Rudert: For reasons we don’t yet understand, some people have no problems with gluten while others will develop celiac disease or gluten sensitivity or rarely, gluten allergy. I’m convinced gluten sensitivity exists—and in far higher numbers than celiac disease. I have over 1,000 celiac patients in my practice. Many more don’t have celiac but improve dramatically on the gluten-free diet.
Q: Speaking of FODMAPs, what’s the connection with gluten?
Fasano: Both gluten and FODMAPs are present in wheat. However, FODMAPs are sugars and gluten is a protein. FODMAPs cause gastrointestinal symptoms because sugars aren’t digested, similar to lactose intolerance. Gluten causes both gastrointestinal and extra-intestinal symptoms due to an immune response.
Guandalini: FODMAPs can cause symptoms, such as abdominal discomfort, bloating, flatulence, that are indistinguishable from gluten sensitivity. The Australian study showed this beyond a doubt. The connection with gluten is through wheat: About 70 percent of the content of wheat is starch (a FODMAP) while about 15 percent is gluten.
Leffler: Both gluten and FODMAP foods are not things we digest super well as humans. If you go low FODMAP, you dramatically lower how much gluten you’re eating. But the reverse isn’t necessarily true.
Rudert: Part of the FODMAP diet is the gluten-free diet—both involve eliminating wheat. However, the FODMAP diet is much more restrictive. Other off-limit foods include certain fruits, vegetables, onions, legumes, dairy and honey.
Q: Could wheat—not gluten—be the problem behind what we’re calling gluten sensitivity?
Fasano: There are many elements in wheat, including gluten, that can be at play and may not be mutually exclusive in causing the problem. Many different components of grains can probably induce immune responses in certain people.
Guandalini: Wheat is composed of a number of compounds that might be responsible for some of what we call gluten sensitivity. Among them are amylase tryptase inhibitors (ATIs), which seem to have an inflammatory effect and may well be to blame for symptoms attributed to gluten sensitivity. But this science is at its dawn. We’ve got a lot of work to do.
Leffler: It’s clear that when we go gluten-free, we change the diet with more than just gluten. That’s the whole thing the Australian group was trying to sort out with FODMAPs. In the future, I think we’ll see a lot of different diet studies taking out different elements of the gluten-free diet and related diets to see what really makes a difference. If you pin most of us down, I think most would agree that what we currently call gluten sensitivity is probably a diverse list of many different disorders treated in the same way because the diets overlap.
Rudert: Some celiac experts have suggested it may be wheat, not gluten, that triggers symptoms. I generally recommend people go gluten-free, not just wheat-free. But who knows? We might find out it’s more of a wheat-related problem. There’s a lot we still don’t know.
Senior medical correspondent Christine Boyd lives in Baltimore, MD.
In Part 2, the experts discuss testing for gluten sensitivity.