‘The Most Popular Diet Ever’: Why Going Gluten-Free Is Risky

A Growing Trend: Diet Common Even Among Those Without Celiac Disease

William F. Balistreri, MD: Hello. I am Dr Bill Balistreri, professor of pediatric medicine at the University of Cincinnati and Cincinnati Children's Hospital. We are here today on Medscape via Skype to discuss the growing trend of gluten-free diets.

Let me first introduce my colleagues. Dr Alessio Fasano is the W. Allan Walker chair of pediatric gastroenterology and nutrition in the Department of Pediatric Gastroenterology and Nutrition at Massachusetts General Hospital, Harvard Medical School, in Boston. Dr Ivor Hill is professor of clinical pediatrics in the Department of Pediatric Gastroenterology at The Ohio State University College of Medicine in Columbus.

The trend that we would like to discuss today relates to the popularity of gluten-free diets. Recent consumer surveys indicate that approximately 1 in 5 Americans have eliminated or reduced the amount of gluten ingested in their daily diet.^[1] This estimate greatly exceeds the small subgroup, approximately 1 in 100, who have been diagnosed to truly have celiac disease.

An analysis of data from the National Health and Nutrition Examination Survey (NHANES) found that while the prevalence of celiac disease has remained stable in the past 5 years, the prevalence of individuals reporting adherence to a gluten-free diet has more than tripled.^[2]

I would like to ask our faculty: Why is a gluten-free diet so popular?

Alessio Fasano, MD: This is one of the most interesting phenomena that we have witnessed in the past few years.

Not long ago, maybe 10 years prior, we were facing a totally different landscape. Ivor and I were both at the University of Maryland School of Medicine at that time, and our Center for Celiac Research embarked on a crusade to increase celiac disease awareness because the gluten-free diet was very difficult to implement. Nobody even knew how to spell "gluten." There were no foods commercially available, as a matter of fact, for those with celiac disease. The most popular item for them to receive as a gift was a bread maker, which they required to make their own bread. Now fast-forward to 2016, and this seems to be by far the most popular diet ever embraced in the United States.

As you said, a huge number of people, almost 90 million, either eliminated or reduced gluten from their diet. How is this possible? Is there a fad component? Of course there is. The reason why is that the actors, actresses, politicians, and sport icons who serve as the popular role models in our culture have decided to embrace a gluten-free diet, and to publish articles and even write books on its benefits. It is a no-brainer for people to then say, "If it's good for her or him, it's going to be good for me to cleanse my body or feel more energized," and so on and so forth. I believe that has really fueled the fad component of the diet.

Referring to the same survey,^[2] what is interesting to me is that if you dissect who is going gluten-free, almost half of people do it because they believe it is good for them, that it is healthier.

If you honestly embrace a natural gluten-free diet, you cannot eat gluten anymore and do not use substitutes, so their statement about the benefits may even be correct because they are forced now not to eat junk food, packaged food, etc. However, if you use and abuse gluten-free products, that is actually not the case. Another third of these people eventually adopt the diet because they want to lose weight, which is implied by the word "diet." That is not the case here. Again, if you use gluten-free counter products, if anything, you gain weight because they tend to be hypercaloric.

You see that this is a mixed bag of people, the minority of whom have a medical necessity to be on the diet and the majority who use it as a lifestyle.

The rest of the individuals are quite interesting. There are some people who claim that they go gluten-free because mainly they have gastrointestinal (GI) symptoms that go away only if they embrace the diet. A miniscule percentage of these 90 million people, or roughly 400,000, have been diagnosed so far with celiac disease and are the only ones that really deserve to be on a gluten-free diet. You see that this is a mixed bag of people, the minority of whom have a medical necessity to be on the diet and the majority who use it as a lifestyle.

The Likely Source of Symptom Relief

Dr Balistreri: Is gluten the culprit in the alleviation of symptoms? Is it related to gluten removal from the diet? What is all this fuss about fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs)?

Ivor D. Hill, MD, MB ChB: Our belief is that there is a small percentage of people in whom gluten is actually the culprit. Take celiac disease out of the picture, because it has a gluten component, the protein fraction of the wheat. We believe that there is a small number of people who have a genuine problem with gluten, but the vast majority of them who are responding symptomatically to the removal of gluten from the diet are probably responding to something else, one of which is the high fructan level that is one of the FODMAPs.

To explain FODMAPs, these are foods that are potentially capable of generating a lot of gas. They are fermentable, which in itself can generate a lot of symptoms. Removing those from the diet may be the reason that a lot of people feel a lot better.

There are also the amylase trypsin inhibitors found in wheat and wheat products, which may also be causing some of the problems.

There is no doubt about it that the majority of people who feel that they are much better on a gluten-free diet are not responding to the removal of gluten per se but are removing something else that comes with wheat and other products.

Dr Balistreri: Alessio, in the spirit of the times and the debate format, I will let you counter that. What percentage of individuals truly have nonceliac gluten sensitivity, and what percentage really are responding to the FODMAP removal?

Dr Fasano: The first question I cannot answer, because until we have validated the biomarkers that will eventually help us to identify who truly has nonceliac gluten sensitivity, it is very difficult to count these people. You can have estimates. They can go from a very conservative 0.5% to the other extreme, where there are people who advocate that 100% of the population has this problem and should avoid gluten, otherwise we will be extinct as a species.

I have to agree with Ivor, with one exception—the FODMAPs. We have to make a clear distinction between food intolerance and food sensitivity.

We have to make a clear distinction between food intolerance and food sensitivity.

Food intolerance is the situation in which you either eat too much of the nutrient or you lack enzymes to digest that nutrient. That creates problems. FODMAPs is one; lactose intolerance is another. What you have as a consequence, as Ivor was alluding to, are exclusively GI symptoms, because you have sugars in the colon that are fermented and give gas and all the symptoms of celiac disease. There is a lot of overlap with irritable bowel syndrome, for example. Indeed, this is one of the most controversial areas noted with gluten sensitivity.

When you talk about a food sensitivity, we talk about immune response. Therefore, you cannot avoid intolerance, but the immune system does something to create the symptoms. These people with nonceliac gluten sensitivity experience GI symptoms, but they also experience non-GI symptoms like chronic headache, chronic fatigue, foggy mind, eczema, and so on and so forth, which you cannot explain with FODMAPs.

This is a long way of saying that I totally agree with Ivor, but we still are grasping the concepts around what we are dealing with. Of course, you also need to consider the placebo effect and the fact that when you embrace this diet, you tend to have a more appropriate lifestyle in terms of nutrition. Just that, and nothing relating to your immune system, may improve your symptoms.

Dietary Downsides

Dr Balistreri: That leads me to my question for Ivor, which is, what is the downside? What are the nutritional deficiencies? Obviously, this is a diet that is low in fiber, high in fat, and perhaps micronutrient deficient. What are your concerns?

Dr Hill: There are a number of downsides to adopting a gluten-free diet if you do not have celiac disease or true nonceliac gluten sensitivity.

There are a number of downsides to adopting a gluten-free diet if you do not have celiac disease or true nonceliac gluten sensitivity.

First, it is an expensive diet, estimated to increase your food costs by about a third. It is not cheap. Second, as Alessio referred to, it is higher in calories. If you compare equivalent foods that are gluten-free as opposed to gluten-containing, there are more calories generally. It is also higher in sodium. Third, it is low in fiber and also lacks calcium, iron, and certain B group vitamins.

If you are going to be on a gluten-free diet, it is really important that you are hooked up with a good nutritionist who can look at some of these factors and make sure you are supplemented to get the extra vitamins, iron, and calcium. This is not to be taken lightly.

Dr Balistreri: To end, let's look toward the future. Alessio, you mentioned biomarkers. Are there any other data that would help us inform the public as to when a gluten-free diet might be indicated, other than celiac disease?

Dr Fasano: Sometimes we forget that with these other conditions, like nonceliac gluten sensitivity, we are in the same situation that we were 30 years ago with celiac disease. We need time to get something robust that will eventually help us to diagnose these people.

Of course, what is needed are double-blind studies, so that eventually we can distinguish whether these people have been respondent solely because of an immune responsive component in wheat, amylase trypsin inhibitors, gluten, or anything else, or rather just because of a placebo effect. If we do not do that, the next step of identifying and validating biomarkers cannot be achieved. There are a couple of studies—including one from our group—that have been looking at that.

Hopefully, we will have some biomarkers to tell us who else—beyond those with wheat allergy and celiac disease, for which we have biomarkers—needs to go on a gluten-free diet for medical necessity, because we'll have a return on investment.

I am rather optimistic that this will be achieved as the goal in the near future.

Dr Balistreri: To summarize what I've heard from you both: If someone decides to be gluten-free, you should first make sure you have excluded celiac disease; that they are aware of the downsides, in terms of both cost and micronutrient deficiency; and that they are truly responding to gluten removal and not something else.

On behalf of Medscape, I want to once again thank Dr Hill, Dr Fasano, and all of our listeners.

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