Celiac disease is an autoimmune disorder where the ingestion of gluten, a protein found in wheat, rye and barley, leads to damage in the small intestine. This disease affects approximately 1% of the population.
Currently, the only treatment for celiac disease is to eliminate gluten completely from the diet. Even small amounts of gluten, without noticeable symptoms, can cause serious damage and inflammation in the small intestine. Eating gluten triggers an immune response that damages intestinal villi, the fingerlike lining of the small intestine. Due to the damaged villi and inflammation the absorption of nutrients is disturbed.
When being undiagnosed or left untreated, the malabsorption of nutrients can lead to vitamin and mineral deficiencies and cause conditions such as lactose intolerance and iron deficiency anemia. The risk for developing osteoporosis, gastrointestinal cancers and central and peripheral nervous system disorders is also increased. If left untreated, celiac disease may also lead to development of other autoimmune disease including Type 1 diabetes and multiple sclerosis (MS).
There are also people, for whom celiac disease has been excluded, who claim to suffer from gastrointestinal symptoms due to eating gluten. This condition is often referred as non-celiac gluten sensitivity (NCGS). Typically, symptoms are self-reported, while no abnormalities in biomarkers, such as C-reactive protein or intestinal permeability, are observed.
A recent Norwegian double-blind crossover study possibly sheds some light to the issue of non-celiac gluten sensitivity by suggesting that fructan, rather than gluten, may be the true cause of stomach symptoms experienced by people with NCGS.
In the Norwegian study 59 individuals on a self-instituted gluten-free diet, for whom celiac disease and IBS had been excluded, were randomly assigned to diets containing gluten, fructans, or a placebo, concealed in muesli bars, for 7 days. Interestingly, the most symptoms were observed on diets containing fructans, while there was no difference between the gluten and placebo groups.
Fructans can be found in wheat, rye and barley, which are also the grains containing gluten. This may explain why, as a result of removing these grains from the diet, people with gastrointestinal problems self-diagnose themselves with NCGS.
The results from this study give some hope to all of the bread lovers out there. The fermentation process that occurs in the dough when preparing sourdough bread removes fructans. As a result, the fructan concentration in sour dough products is significantly lowered. These products still contain gluten, but may be suitable for those people who are intolerant to FODMAPs and fructan, rather than suffering gluten sensitivity.
Fructan is one of the FODMAPs (Fermentable Oligosaccharides, Di-saccharides, Monosaccharides And Polyols) that are short-chain carbohydrates, more poorly absorbed, compared to other carbohydrates such as long-chain starches and well-digested simple sugars, in the small intestine. These carbohydrates can therefore be rapidly fermented by bacteria in the gut. The production of gas by these bacteria is often a major contributor to symptoms observed among people suffering from irritable bowel syndrome (IBS).
People diagnosed with IBS are sometimes advised, in addition to a low FODMAP diet, to try a gluten-free diet as some patients report benefits gained. Clinical studies on the effects of gluten in IBS patients have however, given somewhat contradictory results.
Just to name a few examples, in a small cross-over study participants suffering from IBS, who believed they had non-celiac gluten sensitivity, first followed a 2-week reduced FODMAP-diet and were then placed on high gluten, low gluten or no-gluten diet for 1 week. During the reduced FODMAP-diet, gastrointestinal symptoms improved in all participants. Interestingly when exposed to the test diet, symptoms worsened to a similar degree with all diets, including also the control diet. Gluten-specific effects were observed in only 8% of the participants, while no diet-specific changes in any of the biomarkers were observed.
In another study with IBS patients, who were controlling their symptoms by following a gluten-free diet, participants received either gluten or a placebo in the form of specially made bread and muffins. In contrast to the results observed in the previous study, those participants exposed to gluten reported significantly worsening stomach symptoms compared to the placebo group, but again the study was unable to identify any difference in biomarkers that were measured.
It may be that some IBS patients truly gain some additional benefit from following both, low FODMAP and gluten free diets. On the other hand, as suggested by the new Norwegian study, avoiding FODMAPs rather than gluten may reduce gastrointestinal symptoms among those who do not suffer from either celiac-disease or IBS, but rather have just self-diagnosed with gluten-sensitivity.
Altogether, avoiding gluten has become a major trend in some western countries, as many people associate gluten-free diets with falsely stated health benefits. People who avoid gluten for no specific medical reason may think that they are now eating healthier, but in reality, it may be quite the opposite.
This issue was also tackled by an article where professors from the Arizona State University examined the reasons behind the gluten-free mania. It reports on studies where gluten-free diets have been associated with deficiencies in iron, calcium and fiber and adverse effects on gut health. The article also suggests that gluten-free products may contribute to elevated glucose levels, as sometimes gluten-free products contain less fiber (or other nutrients), compared to gluten-full alternatives.
The food industry surely answers to the demands of consumers and skillfully endorses food trends that are backed up with belief rather than science. If considering a gluten-free diet, it’s a good thing to keep in mind that in the end the assumed benefits may be canceled out by the consumption of less nutritious gluten-free alternatives and a one-sided diet. Therefore if non-celiac disease gluten sensitivity is suspected, a careful evaluation, preferably by a specialized nutritionist or a dietitian, may be in order. If gastrointestinal symptoms are eventually linked to gluten you should work with a professional to revise the gluten-free meal plan to ensure a balanced diet that fulfills all nutritional needs is recommended.