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Oats appear safe for patients with celiac disease
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Adding oats to increase the nutritional value of a gluten-free diet does not appear to affect symptoms, histology, immunity or serologic features of patients with celiac disease, according to new research published in Gastroenterology.
These results are “reassuring, and suggest that non-contaminated oats are tolerated by the great majority of patients,” Peter H. R. Green, MD, professor of medicine at Columbia University Medical Center, and director of the Celiac Disease Center at Columbia University, and colleagues wrote. However, they noted that their “confidence is limited by the low quality and limited geographic distribution of the data.”
Peter H. R. Green
“We found no evidence that addition of oats to a [gluten-free diet] affects symptoms or activates celiac disease,” María Inés Pinto-Sánchez, MD, MSc, and Elena F. Verdú, MD, PhD, both of the Farncombe Family Digestive Research Institute at McMaster University, Ontario, Canada, told Healio Gastroenterology via email. “However, we should take into consideration that there were few studies in some of the analyses, most of them were conducted in Europe, and the quality of the evidence was graded as low. The study highlights the need of more rigorous trials from different regions of the world, as the purity of oats will depend on the country of origin and local regulations. Until then, we endorse the recommendations by the North American Society for the Study of Celiac Disease (NASSCD) to support the use of pure oats in [celiac disease], but to monitor levels of tTGA before and after their introduction into the diet.”
Pure oats avoid gluten contamination in their production and are generally considered safe for patients with celiac disease, whereas traditional commercial oats are often contaminated, according to the researchers.
However, some studies have suggested oats themselves may be harmful, while later studies have concluded otherwise, they noted.
“The protein fractions considered to be the constituents of most concern in celiac patients include the alcohol-soluble fractions (prolamins) of wheat (gliadins), rye (secalins) and barley (hordeins),” the researchers wrote. “The prolamine fraction in oats (avenins) is structurally different from other prolamin fractions, and represents only a small proportion of total oats protein.”
María Inés Pinto-Sánchez
Elena F. Verdú
To better address the controversies surrounding the safety of adding oats to a gluten-free diet, Green and colleagues reviewed studies evaluating the safety of oats as part of a gluten-free diet in patients diagnosed with celiac disease or the related skin condition dermatitis herpetiformis. They ultimately included 28 studies published up to January 2017 in their analysis, six of which were randomized controlled trials that used pure uncontaminated oats, and two of which were non-randomized controlled trials (RCTs, n = 661), while the rest were observational studies. Only RCT data were included in a meta-analysis.
One year of eating oats showed no significant effects on symptoms, histologic findings, intraepithelial lymphocyte counts, or serologic test results. These findings were comparable in both adults and children.
Further, the results of three non-RCTs suggested that dermatitis herpetiformis lesions did not worsen after consumption of oats. No studies compared regular vs. pure oats.
The investigators noted that all available RCTs were conducted in Europe, and because the purity of oats depends on the country of origin and its regulations, there is an “urgent need for studies in North America and other regions of the world where [celiac disease] is prevalent. Results from studies in Europe using locally sourced oats cannot be extrapolated to North America.”
They concluded that available data suggest celiac patients can safely consume non-contaminated oats, but more rigorous data are needed. – by Adam Leitenberger
Disclosures: The researchers report no relevant financial disclosures.
Editor's Note: This article was updated on April 25 with additional comments from the study investigators.
Perspective
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Anthony J. DiMarino, Jr., MD
Dr. Green and his colleagues have made a fine effort to help clarify the issue of whether adding oats to a gluten-free diet in patients with celiac disease may be harmful.
It is very difficult to observe a strict gluten free diet in patients with celiac disease. Studies have suggested that between 50% to 70% of patients with celiac disease are either directly or more likely inadvertently exposed to gluten. Taste fatigue is an issue with celiac patients and therefore, in addition to being a good source of protein, oats would be a welcomed addition to their diet.
Prolamines are the alcohol-soluble portion of the protein in wheat, rye and barley, and are antigenic in celiac patients. The prolamines in oats are not antigenic, so theoretically it’s possible that eating oats should not be harmful to celiac patients. However, some prior studies have suggested that celiac patients may experience a reaction to eating oats.
I applaud the researchers for completing a rather Herculean review of 433 articles, and then reporting on only 28 articles of reasonable enough quality to be included in their study. Unfortunately, only six were randomized controlled trials, with half in adults and half in children.
It is important to note that only two small studies were conducted in North America and only one in the U.S. Most studies had been completed in Europe. Twelve of the studies were from Finland where approximately 2.5% of the population has celiac disease. The Finns and many Scandinavian countries are more aware of celiac disease and the oats available in these regions are likely to be of higher quality and thus less likely to be cross-contaminated with gluten than those available in the U.S.
In addition, the one Canadian study only involved 15 subjects, and the one U.S. study only involved 10, so to apply the conclusions from this article to patients in the U.S, and probably in North America, are questionable. The authors recognized that both the conclusions from these studies performed in Europe may be problematic elsewhere and that the quality of the studies could be improved upon. Furthermore, they suggest that there is a need for more rigorous, randomized controlled trials.
At the Jefferson Celiac Center, we believe the science behind the idea that the prolamine component of oats is safe as compared with the prolamine in wheat, rye and barley. However, we also recognize that cross-contamination of the oat supply is more likely in the U.S. than in Europe. Therefore, we advise newly diagnosed celiac patients who are still symptomatic to avoid oats. Once their anti-tissue transglutaminase or deamidated anti-gliadin antibody levels normalize, and they become asymptomatic, we advise them to cautiously introduce the purest form of oats available as there are several products that avoid cross contamination. If they become symptomatic again after consuming oats, we know that either cross-contamination has occurred, or they may be one of the perhaps 5% to 10% of patients who also may have an intolerance of oats for reasons unrelated to celiac disease.
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