Sunday, July 01, 2007
Why wheat gluten is not safe to eat
Despite reassurances by the grain industry that the current high gluten wheat flour and grains making up much of our current diet are safe for those without celiac disease, it isn't true according to new research. Scientific evidence is accumulating explaining why many eating such a diet are ill and feel better on a gluten free diet even when they don’t have celiac disease. Are you one of them? Researchers from Spain describe an abnormal immune response to gluten in humans whether they have celiac disease or not.
Gliadin, a protein produced from the digestion of gluten, increases intestinal permeability. This effect is noted in intestinal tissue regardless if someone has celiac disease. In those with celiac disease the gut injury from gluten is worse and produces a leaky gut that lasts longer than in those without celiac disease. The ability of gluten to damage the intestine more severely is clearly linked to certain white blood cell patterns that are inherited. The leaky gut persists in people with celiac disease as long as they continue to eat gluten-containing foods because of a genetic predisposition tied to white blood cell protein patterns designated DQ2 and DQ8. Those with these patterns are at much higher risk for gluten induced intestinal injury.
White blood cells carrying DQ2, DQ8 or both patterns can develop an abnormal adaptive immune response to gluten (gliadin). Most people carrying these patterns do not have both abnormal innate and adaptive immune responses to gluten resulting in celiac disease. However, many people with and without these patterns have symptoms that are worse while eating gluten and better on a gluten free diet. Why is that?
Bernado et al. from Spain help with the explanation of how gluten can do this. In their report in the May 2007 issue of Gut 2007 the report evidence of an altered innate response to gluten (gliadin) in people WITH AND WITHOUT celiac disease. They propose that an abnormal innate immune response is common in patients with and WITHOUT celiac disease regardless of genetic make up, that is DQ 2 or DQ8 status. They report that there is an abnormal innate immune response to gluten producing chemicals in the intestine resulting in injury (and therefore leaky gut and symptoms).
However, abnormal adaptive immune response results in more severe intestinal injury (abnormal small intestine biopsy) and abnormal specific blood tests (endomysial and tissue transglutaminase antibodies) now required for the formal diagnosis of celiac disease. It is often forgotten that before these tests were available, the diagnosis of celiac disease was based on symptoms and response to a gluten free diet. Celiac disease as defined as the presence of villous atrophy on intestinal biopsy and abnormal EMA and tTG antibodies is almost entirely restricted those with DQ2 and DQ8. Why is this?
Increased intestinal permeability due to activation of intra-epithelial lymphocytes in DQ2 or DQ8 positive individuals is known to cause severe intestinal injury that further increases gut permeability from gluten. However, not everyone with these genetic patterns develop celiac disease. In the absence of these white blood cell patterns, it is rare to develop severe intestinal injury and positive specific blood tests.
I believe however, it is quite clear that gluten (gliadin) causes leaky gut even in normal people. This likely due to activation of immune cells that release chemicals called cytokines that injure tissue and cause symptoms. Immune activation of lymphocyte white blood cells and intestinal injury commonly results in elevated gliadin antibodies and non-specific intestinal biopsy abnormalities in people who don’t have celiac disease but respond to a gluten free diet.
Though such individual do not and may never meet diagnostic criteria for celiac disease despite the presence or absence of DQ2/DQ8 genetics, many of these do have improved symptoms, normalize their gliadin antibodies and any intestinal biopsy abnormalities when offered a gluten free diet trial. Withholding, discouraging or failing to suggest a trial of gluten free diet from such people because they do not meet diagnostic criteria for celiac disease or or are DQ2 and DQ8 negative seems cruel. Considering the accumulating scientific notwithstanding the experience of many people who are better on a gluten free diet, it is unwise to not consider gluten as a reversible cause of illness. It is however, better to undergo appropriate evaluation before starting a gluten free diet to avoid missing the diagnosis of true celiac disease.
The new information coming from celiac disease research indicates to me that gluten may not be good for you regardless if you have celiac or not. But I already knew that from personal and professional experience. If you are not sure if gluten is bad for you or want more information about the differences between the innate and adaptive immune response, see the research page on my website
www.theFoodDoc.com and my other articles.
Bernado D. et al. Is gliadin safe for non-coeliac individuals. Production of interleukin 15 in biopsy culture from non-coeliac individuals challenged with gliadin peptides. 2007 56:5; 889
Drago S. et al. Gliadin, zonulin and gut permeability: Effects on celiac and non-celiac intestinal mucosa and intestine cell lines. Scand J Gastroenterol. 2006;41(4): 408-419.
Maiuri L. et al. Association between innate responses to gliadin and activation of pathogenic T cells in coeliac disease. The Lancet. 2003;362(9377):30-37.
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