Brian Lacy, MD, and Benjamin Lebwohl, MD, on the Gluten-Free Diet for Celiac Disease

Drs Lacy and Lebwohl continue their podcast series with a discussion on the gluten-free diet and its importance in controlling celiac disease.

Hear the previous podcasts in the series here and here. 

Brian Lacy, MD, is a professor of medicine and gastroenterologist at Mayo Clinic Jacksonville, and Section Editor for Stomach and Small Bowel Disorders for the Gastroenterology Learning Network. Benjamin Lebwohl, MD, is the Louis and Gloria Flanzer Scholar, an associate professor of medicine, and director of the Celiac Disease Research Center at Columbia University Medical Center in New York.

TRANSCRIPT:

Rebecca Mashaw:  Hello, and welcome to another podcast from the Gastroenterology Learning Network. I'm your moderator, Rebecca Mashaw. Today, we continue our series on celiac disease with doctors Brian Lacy and Ben Lebwohl.

Dr. Brian Lacy:  I'm Brian Lacy, Professor of Medicine at the Mayo Clinic in Jacksonville, Florida. I'm continuing my conversation on celiac disease with Dr. Ben Lebwohl, Associate Professor of Medicine and Director of the Celiac Disease Research Center at Columbia University in New York City.

Ben, in our last podcast, we talked about the tests and biopsies that can help solidify or eliminate the diagnosis of celiac disease. Let's talk about the key for managing celiac disease, the gluten-free diet and the challenges it can present to our patients.

We now know that many adult Americans are on a gluten-free diet for any number of reasons. This is now a multi-billion-dollar-a-year industry. Can you help our listeners with how you discuss the difference between celiac disease and non-gluten wheat sensitivity to your patients?

Dr. Ben Lebwohl:  There is so much uncertainty about nonceliac gluten sensitivity, also referred to as nonceliac wheat sensitivity, because we're not sure it's necessarily the gluten in the wheat that's making patients feel ill. Gluten is the protein component of wheat. Maybe it's not that.

The way I frame it with patients is, we understand what's going on in celiac disease in terms of the biomarkers or the things that become abnormal in celiac disease. That helps us diagnose it. We understand the epidemiology. We understand the natural history, associated conditions, needing to monitor patients, and thinking about long-term risk.

We understand very little of that in nonceliac gluten sensitivity. This latter condition we consider to be more of a clinical phenotype. It is based on what the patient's signs or symptoms are that seem to temporarily correlate with gluten exposure and yet in whom celiac disease has been adequately ruled out.

That last point is important. Many people with nonceliac gluten sensitivity have not had an adequate or full workup for celiac disease. Often is the case that they have started a gluten-free diet without first seeking healthcare or evaluation, and so without getting the tissue transglutaminase IgA antibody.

Once they present, if they've already been on a gluten-free diet for a year, then doing a tTG IgA is unlikely to rule out celiac disease. It's likely going to be negative, and we don't know if that means they have well-controlled celiac disease or they never had celiac disease to begin with.

In a situation like that, I go over this with the patient and let them know that there are advantages to knowing your celiac status. The major advantage is that gluten-free diet is a long-term strategy. We don't allow for liberalizing that diet, whereas, if someone has nonceliac gluten sensitivity, we say, "You can let your symptoms be your guide."

If you're traveling or if you're in a restaurant and you want to try some gluten-containing item, if you've got celiac disease, you can't do that. If you have nonceliac gluten sensitivity, you can deal with the consequences the way someone with lactose intolerance might deal with the consequences when you're deciding whether to partake in a certain food.

That's one major reason. The other is long-term monitoring and screening of relatives, potentially. To help people figure out, there is the role of HLA typing. If they don't have DQ2 or DQ8, celiac disease is ruled out.

If they do have one of those genetic markers, then there may be a role for a gluten challenge, where we have the patient, if they're willing and able, to eat gluten, typically a couple of slices of bread a day for 2 to 3 weeks, followed by testing, most typically a duodenal biopsy, followed possibly by serologies.

That may uncover a diagnosis of celiac disease. If everything is coming out normal in that setting, then that person likely does not have celiac disease. The last thing I'd say about nonceliac gluten sensitivity is that it's important for both doctor and patient to keep an open mind. It turns out that it's not always gluten.

Starting a gluten-free diet is a major lifestyle change, and that might result in improvement of a number of symptoms, even if it wasn't the gluten itself that was being cut out. Some people starting a gluten-free diet eat substantially less because they're restricting.

In some people, they feel better because a gluten-free diet has a lot of overlap with a low FODMAP diet and they are treating their undiagnosed irritable bowel syndrome. In still others, it was fructose intolerance. There are a number of reasons someone who cuts out gluten might feel better.

Double-blind, placebo-controlled trials have borne this out that it's only in a minority of patients with self-diagnosed nonceliac gluten sensitivity that it is the gluten that is the culprit. It's a heterogeneous group of conditions. In some people, it is gluten. In some people, it's something else.

It behooves us to keep an open mind about that and potentially initiate a targeted workup in someone with self-described gluten sensitivity.

Dr. Lacy:  Ben, that's great. We're going to come down in a minute or two to possible downstream consequences, another reason for teasing out celiac disease from nonceliac wheat sensitivity. Ben, as we all know, the treatment for celiac disease is a wheat-free diet, as you just mentioned.

It sounds so easy, but we know it's incredibly complicated and can be expensive and time consuming. You've done some interesting research in this area. Tell us about some of the foods most commonly considered to be gluten or wheat free but are contaminated.

Dr. Lebwohl:  Gluten-free diet is easier said than done, and every patient experiences this. I should say, when I'm seeing a patient with celiac disease for follow-up, one of the standard questions I ask is, "When was the last time you got exposed to gluten unintentionally?" Nearly every time, the patient will tell me, "Sometime in the past month or two."

Traveling and eating out are certainly the areas most rife for inadvertent gluten exposure. In terms of specific foods, we studied this. We analyzed crowd-sourced data from people with celiac disease who were using a portable gluten detection device.

They were testing foods when they were eating out at restaurants, and then this device would say whether gluten was detected in that food of possible gluten content. These diners, they were uploading results so that you can see how often certain foods may have gluten.

The 2 items that had the highest hit rate in terms of gluten in these apparently gluten-free items were pizza and pasta. Even before we had that data, this is what I was hearing from patients. They were not surprised to hear this, especially those who get symptomatic when they're exposed to gluten. Eating a gluten-free pizza in a restaurant has its hazards.

If it's prepared, for example, in an oven where gluten-containing pizzas are sitting right next to it, you can imagine there's cross-contact. Also, if it's being handled by handlers who aren't wearing gloves and maybe handling gluten-containing pizza dough and then immediately move to the gluten-free pizza, you can again imagine cross-contact.

Pasta may be related to reused water. Pasta is prepared in a big pot of boiling water. If that gluten-free pasta was put in a pot of boiling water that had just prepared gluten-containing pasta, you can imagine, especially in people who are sensitive at the milligram level to gluten, that this could potentially cause symptoms and have a detectable amount of gluten for these sensors.

Those are the 2 items that diners with celiac disease need to be aware of. It might be worth initiating a conversation with the food-handling staff or potentially choosing something else on the menu.

Dr. Lacy:  Ben, as usual, you're always one step ahead of me, and you beat me to the punch. I'm thinking we're still in this horrible COVID pandemic. A lot of our patients don't eat out anymore. They don't order out. They don't do carry-out.

Thinking about life a year ago, when we were eating out, and you go to a restaurant, how accurate is it when it says it's gluten-free? Do you think it's 90% accurate, or 70%, or 50%, or is it just a flip of the coin?

Dr. Lebwohl:  In that study of apparently gluten-free food, there were certain items, like pizza, pasta, where well more than a third of these items tested positive for gluten. Of course, that's a study where people are volunteering to report. They might be more likely to report the surprising result where a gluten-free food has gluten detected in it.

The actual prevalence of gluten in such foodstuffs is hard to measure. There have been some smaller studies where undercover diners would order a bunch of gluten-free pizzas and not eat them but send them to a food chemistry lab.

The results have been discouraging in terms of significant amounts, or numbers, of these pizzas having detectable gluten, detectable over the 20 part per million threshold, which we believe is the clinically relevant threshold, the amount that if you were to have a full serving, you would then end up with enough gluten quantity that would potentially cause symptoms, and even intestinal damage if this happens over the long term.

In terms of how common this happens in real life, we rely on symptoms to some degree and also, frankly, reputation. These gluten sensors are potentially promising technology. They have their own issues, though. None are perfect. Some might even be detecting such small amounts of gluten that they might not be clinically relevant.

Ultimately, what we advise our patients to do is to talk to the food-handling staff and get a sense of whether they're taking them seriously, whether they appear to be knowledgeable about the kind of precautions that should be taken or whether they're rolling their eyes at the person asking the question.

Frankly, some people see gluten-free as a food fad, not to be taken seriously. That's a real problem if you're dealing with someone with celiac disease, who needs to minimize any chance of significant gluten exposure. Sometimes, it's not a device, and it's not data, but it's your read of the conversation that determines whether it's a safe place to eat.

Dr. Lacy:  Great teaching points. Ben, thanks for another great podcast.

Rebecca Mashaw:  We hope you'll join us for the next installment in this series, in which doctors Lacy and Lebwohl will discuss the long-term consequences of uncontrolled celiac disease.