Tuesday, March 19, 2013

Glutens and Celiac Disease

There was a recent article in the New York Times about gluten and celiac disease. Since then I have received a lot of questions about this disease. In fact, it is the most commonly asked question I hear when a patient comes in with bloating, gas and irritable bowels. Though physicians have thought it was a rare diagnosis in the past, it turns out that 1 in a hundred to 1 in three hundred of the U.S. population is afflicted with this illness. The minority of celiac disease is diagnosed due to mild disease without symptoms.

I came across a very interesting article in Medscape Gastroenterology, March, 2013, by Dr. David Johnson, Professor of Medicine and Chief of Gastroenterology at Eastern Virginia Medical School in Norfolk, VA.  It is good, and would like to share it with you.

From Dr. David Johnson, Medscape Gastroenterology, March, 2013

Gluten-sensitive enteropathy is something that we probably need to think more about. Patients are all abuzz with this concept of gluten withdrawal, and they are saying, "I feel better. What can you tell me about this?"

I thought it would be helpful to review this topic. A recent article in the New York Times [1] caught my eye, and lo and behold, it was about an excellent article in the February issue of Gastroenterology and Hepatology by William Chey's group[2] at the University of Michigan. I thought it was time to take a look at the data and put some science behind what is currently a field that is running without much guidance.

What Is Gluten and What Is Celiac Disease?

First, let's talk about gluten. Gluten is a component of wheat and wheat-related grain products. When you start to talk about gluten withdrawal, is it really gluten withdrawal or is it wheat-product withdrawal or grain-product withdrawal? Grains are complex carbohydrates that have a number of fermentable sugars, which we would frequently remove from patients' diets because most of them are polyglycols -- fructans and galactans. We know from experience that when you withdraw fermentable sugar from patients, they frequently have improvement in symptoms such as bloating, gassy discomfort, and diarrhea.

Now let's focus on celiac disease. The prevalence of celiac disease has increased over the past several decades. Some inferential data suggest that some of it may be related to the hybridization of wheat and related grain products over the past several decades. We may actually be sensitizing more people, causing gluten-sensitive enteropathy or non-celiac gluten sensitivity, which we will discuss later.

We found that gluten-sensitive enteropathy is responsive to gluten withdrawal, but now we are seeing other patients who tell us that they feel better if they withdraw gluten. And they have found this out by going on the Internet or talking to friends and family who have had causal experience with this. Now we have patients out there doing a variety of things on their own accord and without a lot of medical judgment. That is not so good, particularly when you start talking about withdrawal and restrictive diets.
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Who Is Affected by Gluten?

Is celiac disease more common in patients with irritable bowel syndrome (IBS)? We
see a lot of overlap in the symptoms of gassy discomfort, bloating, and diarrhea. Cash and colleagues[3] published an article in Gastroenterology in 2011 that looked at the prevalence of celiac disease in patients with IBS symptoms and in those without symptoms but who underwent routine colon screening or surveillance. No difference was found in prevalence between the 2 populations. Interestingly, they did find increased markers for an immunologic response to gluten with antibodies against tissue transglutaminase (tTG), gliadin, and endomysium. They were increased with an odds ratio of about 1.5 in people with IBS. Although they did not meet the criteria for celiac disease, these patients were immunologically manifesting some reaction to wheat-related products.

Does this mean that people who have immunologic or some type of phenotypic predisposition to celiac disease have more sensitivity to gluten? A very interesting article that was published about a decade ago looked at patients who had some evidence of diarrhea-dominant irritable bowel syndrome (d-IBS).[4] They looked at the response to gluten withdrawal and found that there was a sizable percentage of people who had phenotypic markers for celiac disease but did not manifest celiac when they did duodenal biopsies. They were positive for the HLA-DQ2 or DQ8 phenotypic markers for celiac disease, but for histologic manifestations they did not meet the criteria for celiac disease. The investigators found that patients with other immunologic responses (eg, antigliadin antibody positive or tTG positive) responded better to withdrawal of gluten. In fact, a subset of patient populations with d-IBS will respond to gluten withdrawal if they have immunologic predisposition by their phenotype in addition to another immunologic manifestation, particularly the IgG antibodies that you see against gluten.

What Is Non-celiac Gluten Sensitivity?

When we talk about non-celiac gluten sensitivity, what are we talking about? We are talking about a patient population that has some form of symptoms or morphologic response after exposure to gluten, and they get withdrawal-related benefit. That would be gluten-sensitive non-celiac disease. Associated symptoms have been described as both classic intestinal (ie, gassy and crampy discomfort, bloating, and diarrhea) and extraintestinal (ie, malaise, fatigue, or attention-deficit disorder). An ataxic gait has also been described with gluten sensitivity.

Now let's take it a step further and ask: In patients who have gluten sensitivity and who feel better after gluten withdrawal, is it real or not real? In a very nice study[5] that was published about 2 years ago, investigators looked at patients with d-IBS in whom all the serologic markers for gluten were negative, but they felt better when they had gluten withdrawal. It was a randomized, double-blind, placebo-controlled trial. They only had 34 patients, but they were randomly assigned to receive bread and a muffin with gluten or bread and a muffin without gluten.

At the end of 6 weeks, there was a significant reduction of symptoms in the group that was receiving gluten-free food compared with the group receiving gluten. Gluten withdrawal resulted in a much more satisfactory response, with resolution of diarrhea, stool composure, gassy discomfort, and pain from bloating. Fatigue was also improved, which is interesting. I wonder if many of these patients were having sleep disruption at night.

How Does Gluten Cause Problems?

How does gluten cause problems? In celiac disease, it causes disruption of intestinal permeability, which is driven by an upregulation of zonulin. Zonulin regulates intestinal permeability. However, no such response is seen in gluten-sensitive non-celiac patients. Then why are these people having problems? I am not ready to say that it's all gluten, but gluten may be part of the problem.

Think about where we see gluten. It's in wheat products and a variety of grain products. For IBS, fermentable sugars can be reduced with the low-FODMAP (fermentable oligo-di-monosaccharides and polyols) diet, which is a reduction in gluten. When you take fructans and galactans -- the gluten or the related grain product itself with the fermentable sugars -- and dump them into an environment that is rich with intestinal flora that can ferment these sugars, you change osmotic load and you change intestinal fluids. You may change upregulation with sensitivity and motility changes, and there may also be microflora changes as you start to have a more acidic environment and you begin to manifest complex short-term fatty acids. These may change the intestinal flora, so it is difficult to say that everything is related to wheat and specific to gluten until we have better trials.

Testing and Treatment

What should we do with these people? If you have a patient who has diarrhea, gas, and bloating, it's very reasonable to do serologic testing. I think celiac disease is still missed in many patients. If you have a celiac patient who is negative for the standard profile and still has symptoms, it's reasonable to do HLA typing and the DQ2 or DQ8 profile. It would certainly give you an idea of whether this patient may do better after withdrawal of gluten, particularly if you could combine it with another marker. If the patient is antigliadin positive and tTG positive, start to look at phenotypic markers as well.

In trying to make patients totally gluten-free, it is very challenging to tell them to be totally restrictive. In my practice, I refer them to a nutritionist. There is very strong evidence that when patients are left on their own, a variety of macro- and micronutrient deficiencies can develop. If you are a patient, talk to your doctor. As a physician, I refer these patients to a nutritionist. It has been estimated that the industry is shifting to meet this market with approximately $6 billion in gluten-free products. We know that gluten is not only in food products but in things like beer, cosmetics, and postage stamps. The industry is shifting to meet the need, and fanning the fire is the patient's recollection that he feels better without gluten.

The science is there. It is beginning to emerge. It does make sense, but not in everybody, so be aware of it. Talk to your patients and look hard at potentially finding markers for whether they are more likely to have a response.

These patients are no longer lacking the ability to go out and find gluten-free foods or products. If they are truly celiac, then they have to be a line reader. But for people with non-celiac gluten sensitivity, it remains to be seen how much of an antigenic response will be necessary to truly make the patient feel better. I think it's real. We need to pay attention, we need to be a little bit more pragmatic, and our patients will benefit from this as we learn.