If you have celiac disease or gluten sensitivity and are wondering whether oats are gluten-free, I have the answers for you! I dove deep into the scientific literature and broke down the most important facts in an easy way.
The biggest reason for the interest in this topic is the high nutritional value of oats, which can be a true benefit for someone on a strict gluten-free diet.
If you're wondering whether I'm qualified to write about this topic, I can reassure you. I have a Master's degree in Health Food Innovation Management and experience in reading and summarizing scientific literature.
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What is gluten?
In short: Gluten is a complex (a structure if you want) formed by different proteins. It is commonly found in wheat, rye, barley, and triticale (a cross between wheat and rye).
Let's break it down further
- Contrary to what most people think, gluten is not a single protein. Gluten is a structure formed by different proteins. These "gluten proteins" are often called "gluten" to make it easier.
- The 2 most common proteins that form wheat "gluten" are prolamins (more specifically gliadin) and glutelins (more specifically glutenins).
- Other cereal grains also contain prolamins found in wheat (called gliadins) but have different names. The prolamins in barley are called hordeins, and the ones in rye are called secalins.
- That is why we commonly say that wheat, rye, and barley all contain "gluten". But what we actually mean is that they contain gliadin-like prolamines.
Why is this important?
Celiac disease is an autoimmune disease where antibodies produced by the body's immune system react with gliadins (or hordeins and secalins) (the "gluten proteins" found in wheat, barley, and rye). This reaction causes an inflammatory response that damages the lining of the small intestine and ultimately reduces the efficient absorption of nutrients.
Are oats gluten-free?
In short: Oats are considered gluten-free because they do not contain gliadin, hordein, or secalin, the main "gluten proteins" found in wheat, barley, and rye known to trigger celiac disease.
The complex answer is a little more confusing (so bear with me). While oats do not contain gliadin, they contain avenin, a protein that belongs to the same family of proteins (prolamins) as gliadin. As a result, avenin is often classified as a "gluten protein".
Yet, oats are mostly considered safe on a gluten-free diet because avenin is "less inflammatory" than gliadin. Scientifically speaking, avenin triggers immune T cells at a much lower rate than gliadin and other prolamins. This rate is considered too low to result in a relapse in celiac disease when a patient consumes regular amounts of oats.
So while oats technically contain "gluten proteins", they are generally safe to be consumed by celiac patients.
Let's have a look at scientific studies
- Early studies (1995) found that individuals with celiac disease could consume medium amounts of oats (approx. 50 g/day) without harmful side effects.
- The safety of uncontaminated oats (even over longer periods of time) for celiac patients was confirmed by more recent studies conducted in 2011 and 2012.
- However, a review (2009) concluded that a very small number of people can be sensitive to oats, and should avoid them. One case was reported where a patient experienced intestinal damage.
- A cell study (2004) had already established that avenin (remember, the protein found in oats) can cause inflammatory reactions in cells isolated from celiac patients.
- However, 10 years later, another study (2014) found that while cells can react with avenin outside of the body, the doses of oats commonly consumed are too small to cause a clinical relapse. The authors ultimately support that small amounts of oats can safely be eaten by most celiac patients.
The current consensus for celiac patients seems to be to only consume oats once the patient has been on a gluten-free diet for a while and to stop eating oats if they experience symptoms.
What's the deal with gluten-free certified oats?
- We've seen that oats do not contain celiac-triggering prolamins (gliadins, hordeins, and secalins). So why are they labeled gluten-free?
- The main problem is that oats are often contaminated by other gluten-containing grains. Cross-contamination can happen in the field (when oats are grown close to wheat), during grain transportation, in storage facilities, as well as in milling, or packaging facilities.
- Oats can only be sold as gluten-free if the gluten contamination level is under 20 parts per million (ppm = mg/kg).
- In the EU this threshold is regulated by law in the Annex of the Commission Implementing Regulation (EU) No 828/2014.
- In the US, the same threshold of 20 ppm of gluten is regulated by the FDA.
- In Canada, the threshold by regulated in Health Canada's Marketing Authorization since 2015.
- Producers of gluten-free products can also choose to apply for the gluten-free label from the global gluten-free certification organization.
- To fulfill this requirement, oats need to be processed in separate facilities with several control steps.
So if you have celiac disease or another form of gluten intolerance, make sure to buy certified gluten-free oats and gluten-free oatmeal.
Conclusion
Oats are naturally gluten-free because they do not contain the "gluten proteins" (gliadin in wheat, hordein in barley, and secalin in rye) that trigger celiac disease.
Scientific studies concluded that most people with celiac disease can tolerate small quantities of oats without side effects. However, a very small number of people could still react to oats (or more specifically, to the avenin protein found in oats).
Celiac patients who tolerate oats, have to make sure they buy and eat pure oats that are not contaminated by gluten-containing cereals during the manufacturing process.
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