New Study Finds That the Gluten in Corn Can Damage Celiacs
Those with celiac disease are traditionally told to avoid four types of grain – wheat, rye, barley, and oats. These grains induce chronic inflammation of the small intestine which results in villous atrophy and malabsorption. But is it really the best advice to avoid just these four grains? A growing body of research suggests it is not. And a new study calls into question one grain in particular – corn. If you are just now hearing that corn contains gluten, you are not alone.
What We Know About Corn and Celiac Disease From Prior Research
The Gluten Free Society has followed prior research and has reported in the past that many other grains, such as maize (corn), can be problematic for those with celiac disease and gluten sensitivity.
Our reports are based on recent studies that present evidence that some grains such as maize, traditionally considered safe for celiac patients, could activate the immune response in some celiac patients.
Specifically, recent research has suggested that corn proteins and some corn protein-derived peptides could trigger an immune response. This was shown when an intestine with celiac disease was simulated (using cells in a controlled test tube environment) and found that it induced the activation of certain pathways (IL-8, p38 MAPK, and COX2) that indicate an inflammatory response. In addition, it caused the release of Zonula occludens-1 or ZO-1, which gets released following the disruption of a membrane. The release of ZO-1 may indicate a disruption in intestinal barrier integrity, or leaky gut.
In other research, adverse responses have been reported to maize proteins after an oral challenge in some celiac disease patients.
What the New Study Found About Corn and Celiac Disease
Elevated levels of IgA AZA were found in CD patients compared with IBS patients (p < 0.01) and HC (p < 0.05). CD patients had the highest prevalence (35.1%), followed by IBS (4.3%) and HCs (2.3%) (p < 0.0001).
While prior research looked at the inflammatory response resulting from corn protein, the new study looked at the humoral (antibody-driven) immune response to corn protein. The study analyzed the serum levels and prevalence of IgA and IgG anti-zein (AZA) antibodies (antibodies against corn) in two different inflammatory bowel diseases: celiac disease and irritable bowel syndrome. In spite of the fact that both diseases share a chronic inflammatory condition as the hallmark of their clinical presentation, the study found higher levels and a higher prevalence of IgA AZA antibodies in the celiac disease patient group compared to the IBS patients and to the healthy (non-celiac disease and non-IBS) control patients.
This suggests that the genetic susceptibility in celiac disease may influence the immunological response to other dietary proteins besides gluten in some celiac patients.
These results showing high levels and a high prevalence of anti-zein IgA antibodies in CD patients open two different possibilities to explore with respect to celiac disease:
- A potential cross-reactivity phenomenon between gluten and corn
- A specific immune response against corn proteins in genetically susceptible individuals
In addition, the study authors observed a positive correlation in the celiac disease patients between IgA anti-zein antibodies and the antibodies specific to celiac disease. First, IgA AGA or anti-gliadin (gluten), the key antibody indicator in celiac disease. And second, IgA deamidated gliadin (or IgA DPG, an important serological biomarker with a high sensitivity and specificity in untreated, biopsy-proven celiac disease. IgA DPG is comparable with the widely used tissue transglutaminase (tTG) IgA antibody test.
Limitations of the New Study
It’s important to note that the number of patients with celiac disease in this study was small compared to the IBS and the healthy control groups. In addition, the study was performed in Latin America where celiac disease is underdiagnosed as it is not well understood. Furthermore, only 16 subjects agreed to undergo duodenal biopsies, and so the remaining 21 subjects were diagnosed based solely on the presence of specific antibodies for celiac disease and were classified as subjects with celiac autoimmunity. Still, the findings are clear and compelling.
The common advice to only avoid wheat, rye, barley, and oats if you are gluten sensitive or have been diagnosed with celiac can be misleading and ultimately detrimental to health. That is because those diagnosed with celiac disease often turn to other grains to replace the four commonly cited as gluten free. However, others, like corn, can cause an inflammatory response in the body.
Turning to other grains and experiencing an incomplete healing process can result in the phenomena known as gluten whiplash. This is a scenario observed frequently in clinical practice when a patient starts to develop disease symptoms again after being gluten free for several months. If it has been your experience that you still have symptoms even after following a traditionally gluten free diet, the culprit may be other sneaky gluten-containing grains – like corn.