Cereals, wheat in particular, have a negative image these days. Many believe that it is wise to avoid consumption of wheat, and wheat gluten in particular. This impression if fuelled by widely read books like the “Wheat belly”. So how good is the evidence that wheat and closely related cereals are bad for a relatively large proportion of the population? Well it is fair to say that somewhere between 0.5 and 2 % of the general population (depending on the geographic location) cannot consume wheat, barley and rye. Oat is somewhat of an exception here as most of these people tolerate oats although a few do not. This form of gluten intolerance is called celiac disease. The reason why these people cannot tolerate these cereals is well understood: they have mounted an immune response specific for particular fragments of the gluten proteins and this leads to inflammation in the upper part of the small intestine, where the food meets the mucosal immune system. Just like with immunity to pathogens, this leads to immunological memory. A second encounter leads to a stronger and more rapid immune response. This is why celiac disease is a lifelong disease. The only available treatment is a lifelong gluten free diet.
But in recent years a much larger proportion of the population claims to be intolerant to gluten. Where does this come from and how real is the problem?
Let us start with a few provocative statements. Often they are young women that live in relatively wealthy neighbourhoods. When asked why they are on a gluten free diet they may just reply that they heard from a friend that it is healthier to do so. Many of them do not really know what gluten is and/or in how many food products gluten is used. So in fact, they may still be consuming gluten without knowing it. So partly it seems to be fashionable to say that you are on a gluten free diet. There are nice YouTube video’s on these issues.
Also, it is of interest that gluten-intolerant individuals often eat spelt, a cereal that is currently promoted as a healthy cereal. However, spelt is just another wheat variety and thus gluten rich. So if anybody claims to be gluten intolerant but does consume wheat, it is safe to conclude that the problem is located between the ears. This is an example that I use when speaking for MD’s who frequently encounter gluten intolerant patients. They love it.
One also hears other arguments why wheat is dangerous now while it was not in the past. Genetically modified wheat strains being one of them. But at present there are no genetically altered wheat strains used for foods. So that is definitively no explanation that holds true.
Another argument is higher exposure to gluten proteins compared to the past? Possibly, as pasta and pizza have replaced meat, potatoes and vegetables quite significantly but this is just one of the many changes that we see in our food intake over the last 50 years. If we blame it all on gluten we take a serious shortcut.
Another potential danger associated with wheat are the so-called ATI’s, proteins in wheat that can stimulate the immune system next to the gluten proteins. Here it is important to keep in mind that only individuals with a particular genetic background can develop celiac disease. In contrast the ATI’s are claimed to stimulate the immune system through receptors that we all possess. So if these ATI’s are so important, why are we not all intolerant to wheat???
At present there is more attention for the possibility that the gluten intolerance in really due to incomplete breakdown of carbohydrates present in cereals, so-called FODMAPS. Clinical studies indeed start to provide quite convincing evidence for this possibility. This goes hand in hand with the realization that the intestinal microbiota, which is partly responsible for the breakdown of food components, can differ very significantly between individuals. So perhaps the composition of the microbiota plays a major role in the breakdown of the carbohydrates. If this is really the case manipulation of the microbiota may be the best option to overcome problems that some individuals experience with the consumption of cereals.
Finally, two remarks of a completely different nature.
First, cereals are quite an important component of our daily diet. They provide a cheap source of proteins, micronutrients and essential fibers. Therefore, a true gluten free diet is not easy to accomplish and, if not properly balanced, can cause serious nutritional defects and intestinal discomfort due to lack of fibers. So, do not go on a gluten free diet when there is no real reason to do so.
Second, celiac disease patients are often frowned upon when they say they are gluten intolerant. There is a growing awareness in the general public that most who claim to be gluten intolerant are just following fashion. This complicates the life of patients with celiac disease. So, do not go on a gluten free diet when there is no real reason to do so.
Bio Frits Koning
Full Professor in Immunology in the Department of Immunohaematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands. Member of the Management Team of the department. Head of the section “Immunochemistry”.