Are Oats Gluten-Free?
This is a debate which has raged for a long time, I have seen research dating back to the 1950s on this!
Due to the increased awareness on gluten, gluten intolerances and immune-mediated diseases affected by gluten (celiac disease) this debate has come firmly into the public realm.
One google search for this question and you will find a divide of opinions, not all of them backed by evidence either. Adding to this confusion is many national guidelines and policy statements are also different. For example in New Zealand the position statement from Celiac NZ strongly recommends against oats for those with celiac disease (read their position statement here). Where as in the United Kingdom the Celiac UK website states that "gluten-free oats may be introduced to the diet at any stage, however, a small percentage of people with celiac disease are sensitive to gluten-free oats".
I will get to gluten in a minute but I think the real question should be...
Are oats right for me?
We all want a one size fits all approach to nutrition though this very rarely is the case.
What is Gluten?
I am going to talk a lot about the protein which is a storage protein in grains. But I want to just put some context around this storage protein first. All grains come from developing seeds which synthesise in harvest. They store protein reserves (within each tiny seed) which are used to provide nutrients for the young seedling during germination. Most of these storage proteins - belong to one of two classes:
- The water-soluble storage protein - the globulins
- Water-insoluble soluble storage protein - the prolamines.
The word gluten (which is Latin meaning glue) refers to the prolamine storage protein. Gluten proteins (the prolaimes) have different terms and fractionally different structures:
- Wheat = gliadin
- Barley = hordeins
- Rye = secalins
What do Oats Contain?
Generally most grains (as those above) are made up from the majority of prolaimes, for example the gliadin in wheat accounts for 80-85% of the total protein. However, the prolaime in oats is called avenins and is present in a much lower concentration (10-15%) and the majority of the protein is made up with globulins. More importantly these proteins are free from the known immunogenic epitopes from wheat, barley, and rye which trigger t-cell mediated damage for those that are genetically susceptible (with celiac disease) (Londono et al., 2013).
So Are Oats Gluten Free?
It is clear that the gluten epitopes from wheat, rye and barley are absent from oat avenins. Aligning with this is a large body of robust evidence, including randomised controlled trials (Janatuined et al., 2002), cohort studies (Aronsson et al., 2016) and meta analyses (Pinto-Sánchez et al., 2017) to show that those with celiac disease have no impact from eating oats.
However, there is some evidence to show that there are two avenin-specific epitopes, which can be present in all oat varieties and species, which have been found to be reactive in a very small number of patients (Londono et al., 2013; Gilissen, et al., 2016). What is currently not clear in research is why these two epitopes trigger a reaction in some people with celiac disease and not others. This understanding is hindered by the high risk of contamination (which is a major risk with the industrialisation of the food industry) AND the cross reactivity between epitopes - basically an antibody can bind to these epitopes which can enable a gluten antibody from a wheat protein (for example) to then bind to this and trigger a t-cell response.
I know this blog is getting quite science-based but I believe that this evidence (on both sides so to speak) is important and further highlights the need for the question: 'are oats right for me?'.
I do understand the need for policy statements to ear on the side of caution, especially when an immune-mediated response can occur like with celiac disease. But it is important to note here that there is evidence, a lot of robust scientific evidence to show that oats actually do not have an impact on those with celiac disease - and this is something not discussed on a lot. Given the rise in gluten-sensitivity without an immune response (often called gluten intolerance), this evidence is also important. The trouble with a one-size fits all approach it that it does not take into account the huge variety in individual responses, dietary needs, metabolisms and lifestyles. Oats can be an important source of nutrients for a number of people (you can read more on the health benefits of oats in an earlier blog of mine here). Personally, I believe if you can tolerate them (this includes metabolically) they are one of the most nutrient dense grain options, and can form the basis of a number of homemade recipes. I also love Nairns Oatcakes as a prepackaged snack which is made from 86% real oats (full review here). It is rare to find such a pre-made options with so much natural ingredients.
Are Oats Right for Me?
I am presently working with a vegetarian who has celiac disease. She does not eat meat due to religious reasons so oats are an important source of nutrients for her, especially as she is breastfeeding. Luckily for her she is not affected by oats (has been tested for this) and has access to pure oats - gluten-free oats that have undergone rigorous processing to ensure no contamination. At the same time, I also have a client who has gestational diabetes and struggles to keep her insulin within normal range when having oats (and subsequently we have removed these out of her diet). Two very different responses to oats! I cannot impress on you to really consider all the factors when looking at oats - the question of if they are "gluten-free" does not cover this.
(*note both of these clients have given permission for me to share this with you in the hope it may help someone else to know that it is important to get advise and make dietary changes with professional support).
I do not think there is a yes or a no answer for this one. Looking at the evidence, oats do not have the gluten epitopes that are found in wheat, rye and barley proteins. However, there is a bit of a question mark currently on oat avenins and how they can trigger an immune-mediated response in some individuals. There is also a huge risk of contamination especially as the food industry moves increasingly industrialised. The flip side to this is that in some countries you can now get gluten-free oats (by the way reading how these are produced is fascinating!). Due to the severity of complications for those who have an immune response to gluten, some countries have policy statements to cover this even though there is a lot of robust evidence to suggest otherwise. Be very careful with consulting Dr Google with all of this. I see a lot of forums where, while well-meaning, there is some very inaccurate advice not backed by evidence. It is likely that with further studies we will understand more about oats, celiac disease and how different individuals tolerate this grain - that is research! If in doubt, get an expert opinion before making huge changes to your diet.
xxx Dr Julie Bhosale