The vast majority of people with coeliac disease can include uncontaminated oats in their gluten-free diet. A small percentage of people with coeliac disease are sensitive to oats and should avoid them.
Historically it was advised that oats should be excluded from a gluten-free diet by most UK centres, however a number of studies presented from the mid-1990s onwards have indicated that uncontaminated oats are tolerated by most people with coeliac disease [1, 2]. National Institute for Health and Care Excellence (NICE) guidelines advise that people with coeliac disease can choose to introduce gluten-free oats into their diet at any stage and that the decision to continue including them depends on their immunological, clinical or histological response [3].
Gluten-free oats
Not all oats are suitable for inclusion within a gluten-free diet owing to the likelihood of contamination with gluten-containing cereals during growing or processing. The only oats suitable for inclusion within a gluten-free diet are certified (uncontaminated) ‘gluten-free oats’. Labelling terms such as ‘pure’, ‘organic’ or ‘100% oats’ do not indicate suitability for inclusion. In order to use the claim ‘gluten-free’, manufacturers must comply with legislation that guarantees their products (including those containing oats) contain less than 20ppm (parts per million) of gluten [4].
Why do oats seem to be tolerated by most people with coeliac disease?
Oats contain avenin, a prolamin (storage protein) that is similar to those included under the umbrella term of ‘gluten’, found in wheat, rye and barley. However, most people with coeliac disease seem to be able to tolerate uncontaminated oats. This may be because there are fewer toxic epitopes in oats compared to wheat, rye and barley (although this may vary, between oat cultivars). Avenins may also be more susceptible to breakdown in the gut, rendering them less toxic [5].
Why include oats in a gluten-free diet?
The inclusion of wholegrains (such as oats) within the diet can reduce the risk of heart disease by 15% [6]. Oats are low in fat and high in soluble fibre and have a low glycaemic index. Their inclusion within the gluten-free diet is particularly useful in people with coexistent diabetes mellitus, helping to regulate blood sugar levels and support weight management. Rich in soluble fibre, oats provide benefits to the gastrointestinal system; maintaining overall gut health, increasing stool weight and decreasing constipation [7]. Furthermore, research suggests that a gluten-free diet may be deficient in a number of nutrients including fibre and B-vitamins [8,9]. Oats may help to offset such deficiencies by providing a good source of protein, fibre, B-vitamins, magnesium, phosphate, zinc, selenium, iron.
The future for oats
Several studies have shown that oats are well tolerated by the majority of people with coeliac disease [1,2,10]. However, a small number of people with coeliac disease are sensitive to oats and their intestinal immune status fails to normalise when oats are included in the diet. In these individuals, a strong intestinal T-cell response towards oats has been observed [11], leading to the future possibility of identification of mucosal markers for oat sensitivity amongst coeliac disease [12]. It is understood that some oat strains contain more toxic prolamins than others and further research is needed to develop oat strains with a low avenin content and low immunogenicity [13]. The long term impact of eating oats in those who seemingly tolerate them also needs to be reviewed, as few studies have looked at the long-term effects of oat inclusion
For the vast majority of people with coeliac disease oats are well tolerated and provide benefits in terms of nutrition, variety and taste. Further research is needed to examine why a small number of people with coeliac disease are unable to tolerate uncontaminated oats and what strains of oat cultivar, in what amounts are optimal for ensuring tolerance across all individuals.