Oats, celiac disease

Introduction of Oats in the Diet of Individuals with Celiac Disease A Systematic Review... 

B. Nonpivotal studies testing the effect of oats in patients with celiac disease by in vitro methods... 

Celiac disease is an immune-mediated disease, triggered in genetically susceptible individuals by ingested gluten from wheat, rye, barley, and other closely related cereal grains. The only treatment for celiac disease is a strict gluten-free diet for life. This paper presents a systematic review of the scientific literature on the safety of pure oats for individuals with celiac disease, which historically has been subject to debate. 

Limitations identified within the scientific database include limited data on long-term consumption, limited numbers of participants in challenge studies, and limited reporting about the reasons for withdrawals from study protocols. Furthermore, some evidence suggests that a small number of individuals with celiac disease may be intolerant to pure oats and some evidence from in vitro studies suggests that an immunological response to oat avenins can occur in the absence of clinical manifestations of celiac disease as well as suggesting that oat cultivars vary in toxicity. 

Based on the majority of the evidence provided in the scientific database, and despite the limitations, Health Canada and the Canadian Celiac Association (CCA) concluded that the majority of people with celiac disease can tolerate moderate amounts of pure oats. The incorporation of oats into a gluten-free diet provides high fiber and vitamin B content, increased palatability, and beneficial effects on cardiovascular health. However, it is recommended that individuals with celiac disease should have both initial and long-term assessments by a health professional when introducing pure oats into a gluten-free diet. 

Janatuinen et al. (1995) were the first to evaluate the possible toxicity of oats in a large controlled study. Since then, a number of studies (Table 6.1) have assessed the safety of oats consumption by individuals diagnosed with celiac disease and dermatitis herpetiformis. Most studies were conducted on adults, with a smaller number of studies performed on children. 

Among the studies conducted with children (Table 6.1), there were 89 children with celiac disease, either in remission (n = 13) or newly diagnosed (n = 76), who were challenged with oats added to an otherwise gluten-free diet. All of the children who were in remission at the time of... 

In addition to the pivotal studies, several publications (Table 6.2) used other methods to test the response of individuals with celiac disease who were introduced to oats. These studies did not fulfill the selection criteria of pivotal studies namely an in vivo oats challenge with an intestinal/skin biopsy to assess the biological response to the introduction of oats into an otherwise gluten-free diet. Instead, they used various in vitro techniques to assess the immune response to avenin, or serology without an intestinal mucosal biopsy. Most of the methods used duodenal mucosal cultures prepared from biopsies or intestinal T cell lines obtained from individuals with celiac disease. Other studies measured the immunogenic reaction in peripheral lymphocytes or measured the presence of various antibodies in individuals with verified celiac disease who included oats in their diet, in comparison with a reference group (Table 6.2). Some of these studies used patients that were previously included in pivotal studies. These studies are identified with an asterisk ( ) in Table 6.2. 

In contrast, other in vitro studies (Kilmartin et al., 2003, 2006) report that purified avenin from oats is not immunogenic to the intestinal mucosa of patients with celiac disease. 

The key limitations of the study designs are the duration of the study and the number of subjects. Since most studies conducted are short term, the potential effect of a lifetime exposure to oats requires further investigation. Long-term compliance to a gluten-free diet is one of the major difficulties in the management of celiac disease, and the collection of longterm data related to the consumption of oats is also very challenging. 

From currently available data, one adult patient (1/170) challenged with oats was reported to have a severe adverse reaction to oats. Approximately 6% of adults and 9% of children withdrew from clinical trials due to reported adverse effects from the inclusion of oats in their diet. This evidence, along with the indication from some in vitro studies of an immunological response to avenin in the absence of clinical manifestations of celiac disease and the limitations of the database (previously discussed), supports a cautionary approach for the introduction of oats into a gluten-free diet until the prevalence of oats intolerance among people with celiac disease is well established (Dickey, 2008 Garsed and Scott, 2007). 

Earlier published reviews on the safety of oats for patients with celiac disease were included in this evaluation (Dor and Shanahan, 2002 Kumar and Farthing, 1995 Schmitz, 1997 Thompson, 1997, 2003). Two... 

Wheat, rye, and barley have a common ancestral origin in the grass family. Oats are more distantly related to the analogous proteins in wheat, rye, and barley and the oat prolamins (avenin) have substantially lower proline content. Avenin accounts for 5-15% of the total protein in oats, whereas in wheat, barley, and rye, prolamins constitute 40-50% of the total protein (Kilmartin et al., 2006). Some investigators believe that there are similarities between the protein structure of oats and some wheat-like sequences, which may indicate that large amounts of oats could potentially be toxic to patients with celiac disease. However, the putative toxic amino acid sequences are less frequent in avenin than in other prolamins, which explains the less toxic nature of oats (Arentz-Hansen et al., 2004 Ellis and Ciclitira, 2001, 2008 Shan et al., 2005 Vader et al., 2002, 2003). 

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