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Gluten-free diets: Debunking the myth

In recent years, a great deal of attention has been focused on the use of gluten-free diets to counter a myriad of symptoms such as behavioral problems in children. But what does the science tell us?

In recent years, a great deal of attention has been focused on the use of gluten-free diets to counter a myriad of symptoms, ranging from headache, to abdominal pain and even to behavioral problems in children. While many people, including many high-profile celebrities, bring compelling personal stories about the benefits of such diets, the true efficacy of gluten-free diets in treating non-celiac diseases is unproven. So why do many people swear by these types of diets?

First, let's define a few terms. What is gluten? The word has become common 21st century vernacular and we use it as freely as we use the term "dairy". But what does gluten sensitivity really mean? After all, gluten has been equated to wheat products, other grains, and generally to any bread. In truth, gluten is a very vague term. The Miriam-Webster dictionary defines gluten as "a substance in wheat and flour that holds dough together". The Celiac Disease Foundation defines it as "a general name for the proteins found in wheat (durum, emmer, spelt, farina, farro, khorasan wheat, and einkorn), rye, barley and triticale".

What diseases can scientifically be attributed to gluten? A true food allergy is always a possibility, but we generally define people as being wheat allergic, not gluten allergic, in order to distinguish from those allergic to other grains. These patients present with typical signs consistent with a food allergy, such as hives, vomiting, wheezing, hypotension or full blown anaphylaxis. The symptoms follow in direct chronological proximity to the ingestion of the food, usually within an hour. The treatment includes antihistamines in mild cases, and epinephrine injection for patients with anaphylaxis. At this time, avoidance is the only effective management strategy.

In addition to food allergies, the only other disease that has been scientifically proven to be related to "gluten" ingestion is celiac disease. This is because there is a known autoimmune mechanism for the development of celiac disease. Celiac disease also has a well-defined set of symptoms ranging from abdominal pain to bloating and constipation, and even some skin manifestations. It has been associated with damage to the intestinal lining, a finding which can be verified on a biopsy. Patients with celiac disease also have specific antibodies to gluten.

In the absence of documented tissue and laboratory findings, and in spite of the numerous case reports and anecdotes, gluten has not been proven in well-designed clinical trials to cause any of the many other conditions that it has been implicated in, including behavioral problems, loss of memory, fatigue and difficulty concentrating. Therefore, patients with symptoms should seek help from the physician or specialist in order to rule in or rule out celiac disease. Once ruled out, one should be wary of the promised benefits of a gluten-free diet.

Do gluten-free diets live up to the expectations of a "healthier" diet? It has been suggested that for those people who do feel better after starting a gluten-free diet, they may have a condition that has been become known as "non-celiac gluten sensitivity" or NCGS for short. Unfortunately, this is a vaguely defined condition and is also a "diagnosis of exclusion", meaning that one would make this diagnosis only when one cannot find any other valid reason for the symptoms. Researchers are mostly still scratching their heads in trying to figure out what this condition really is. It is certain possible that such a food intolerance to gluten exists in a very small number of patients, although unlike cow's milk or lactose intolerance, the mechanism is unknown. The manipulation of diet in any clinical setting, it should be noted, is associated with a very high degree of "placebo effect". Moreover, gluten-free diets have taken on somewhat of a fad characteristic, suggesting there may be a role of mass hysteria when it comes to this topic.

Another explanation as to why people might "feel better" when they avoid gluten may be the types of foods that are avoided. Foods containing gluten can be high in carbs such as breads and pasta. Since most American and Western European diets are heavily skewed towards carbs, any reduction in carbs would probably make the individual feel better, but it may not anything to do with the avoidance of gluten!

With this said, when patients ask me about a gluten-free diet to address behavioral problems of their children, I tell them to make sure their children have a well-balanced nutritious diet. If they have a true allergy to a food, usually resulting in a reaction, they should consult their allergist. There is currently no laboratory test to diagnose non-celiac gluten sensitivity. The public should be wary of laboratories that perform bulk food sensitivity studies as many of these tests have no diagnostic value. You should consult your allergist as to what tests are valid or meaningful in the diagnosis of food allergies.

While more future studies are certainly needed, there are no well-designed randomized and reproducible clinical studies that prove that gluten causes behavioral changes or autism at the present time. Nor is there any well founded scientific evidence that a gluten-free diet represents anything more than a fad diet.

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