Coeliac patients know that to follow a gluten-free diet, they must exclude wheat, barley and rye, as well as their varieties and hybrids. However, when the question "do oats contain gluten?" arises, the answer is not always so clear.

For decades, oats were systematically excluded from the gluten-free diet. Today, the current scientific consensus indicates that gluten-free oats can be part of a gluten-free diet, provided that certain safety conditions are met.

Understanding these nuances is key to avoiding unnecessary restrictions, but also to introducing oats judiciously.

From a botanical point of view, oats do not contain gluten. The historical confusion is mainly due to two factors:

• Old studies with contradictory results.
• Consumption of oats contaminated with other cereals that do contain gluten.

The adverse effects associated with gluten are due to storage proteins called prolamins. Each cereal has a different name for them:

• Wheat → gliadins
• Barley → hordeins
• Rye → secalins In oats, these proteins are called avenins.

Prolamins and avenins: what makes them different?

Avenin differs significantly from the prolamins found in other cereals:

• It represents a smaller percentage of the total proteins in oats (between 10 and 20%) compared to those in wheat (between 40 and 50%).
• It has a lower proportion of proline and glutamine (between 35 and 50%) than the prolamins in wheat, barley or rye (70% or more).
• Its structure differs from the classic prolamins involved in coeliac disease.

Furthermore, the specific epitopes of avenin do not trigger a reaction in most people with coeliac disease.

Gluten-free diets can be deficient in certain nutrients, especially if they are not well planned.

Current guidance from the National Institute for Health and Care Excellence, states that coeliac patients can choose to include gluten free oats in their diet at any stage. Patients should be advised whether to continue eating gluten free oats depending on their immunological, clinical or histological response.

Although gluten-free oats are safe in most cases, there are some considerations to be aware of.

It is important to note that a rapid increase in fibre can cause symptoms such as abdominal pain or flatulence, which could be mistaken for relapses.

Sensitive individuals and cultivars

Some people experience adverse symptoms even with certified oats. This could be related to certain cultivars with higher immunogenicity. Currently, the information available on specific varieties is limited and does not usually appear on labelling, so this remains an area of ongoing research.

Oats do not contain gluten in the classic sense of the term. However, the safety of introducing them into a gluten-free diet depends on whether they are certified gluten-free (<20 ppm).

For most people with coeliac disease or gluten sensitivity, their inclusion is safe from diagnosis and can provide nutritional benefits and improve adherence to the diet.

The decision of whether to continue consuming gluten-free oats should be individualised and carried out with appropriate monitoring within the clinical context of each patient.