Yes, the safety of oats is a confusing issue for anyone on a gluten-free diet since the recommendations are in constant flux. Oats are naturally gluten-free. However, oats have a very high risk of cross-contact with gluten-containing grains (wheat, barley, and rye), this can happen through:

• Crop rotation in the field (i.e., growing wheat one year and then growing oats the next season in the same field)
• Harvesting
• Storing
• Transporting
• Processing

Therefore, most commercial sources of oats are heavily contaminated with gluten and not safe for people with celiac disease. It is recommended that people with celiac disease only consume oats that are labeled gluten-free and rigorously tested to contain less than 20 parts per million (ppm) of gluten (1). Twenty ppm has been deemed a safe concentration for people with celiac disease. The Food and Drug Administration requires that products labeled gluten-free contain less than 20 ppm gluten. According to Gluten Free Watchdog Tricia Thompson, MS, RDN, oat products account for nearly half of grain-based products that test too high for gluten content. Oats are difficult to test for gluten content as there may be gluten-containing grains within a batch, and it is hard to get an evenly distributed sample to test (2).

To make things more complex, there are two different methods to make sure oats are gluten-free. It is important for the consumer to know the details of both, so that they can decide on what type of oats is best for them. 

Purity Protocol:

The purity protocol includes oats that have been grown in dedicated gluten-free fields, as well as harvested, stored, transported and processed separately from gluten-containing grains.

Here is a link to manufacturers that use the purity protocol at Gluten Free Watchdog: https://www.glutenfreewatchdog.org/news/oats-produced-under-a-gluten-free-purity-protocol-listing-of-suppliers-and-manufacturers/

Sorted:

Some companies use mechanical or optical sorting to remove wheat, barley, and rye from commercial oats, based on the color and shape of the grain. However, this method is sometimes not adequate to remove all gluten and requires rigorous testing protocols.

Neither method is standardized and can vary, so it is very important that either method includes testing protocols (2).

Check with the manufacturer:

Is the product labeled or certified gluten-free?

What type of oats do they use - purity protocol or mechanical/optically sorted?

What are their testing protocols, and what type of test do they use? The R5 ELISA is regarded as the most reliable test.

Always check with your doctor if it is ok for you to consume oats.

Another issue with oats apart from cross-contact is that a small number of people with celiac disease will react to the protein in oats (avenin) and will have similar symptoms to celiac disease even when ingesting gluten-free oats. Because of this, many doctors recommend to only introduce gluten-free oats once you are stable on the gluten-free diet and your antibody levels have normalized.

Additionally, the high levels of soluble fiber in oats can cause gas and bloating in some individuals depending on the amount they are consuming. It is recommended to introduce oats gradually and drink plenty of fluids to avoid GI symptoms due to fiber. Further, it is recommended that people with celiac disease do not exceed 50 grams of dry oats daily (1).

In Summary:

• Check with your doctor or dietitian who specializes in celiac disease before introducing oats in your diet.
• Educate yourself on the different sources of oats and choose oats that are labeled gluten-free and tested to contain less than 20 ppm gluten. Read through our information on oats.
• Introduce oats gradually to avoid GI symptoms due to increased fiber intake. Do not exceed 50 grams dry oats daily - this is approximately 1/2 cup dry rolled oats, 1/4 cup steel cut oats, 1 packet instant oatmeal, or 1/2 cup oat-based granola. (1)
• If you have symptoms, follow up with your doctor/celiac specialist so they can evaluate the cause of your symptoms.

At NCA we recommend sources of oats that have used the “purity protocol” and tested to contain less than 20 ppm gluten, as well as mechanically sorted oats that have been rigorously tested to contain less than 20 ppm gluten. Read through our resources below to educate yourself on the different sources of oats to decide what is best for you.

Resources:

NCA Information on oats:

https://nationalceliac.org/nca-stance-on-gluten-free-oats/

Here is a list of companies that use the purity protocol from Gluten Free Watchdog:

https://www.glutenfreewatchdog.org/news/oats-produced-under-a-gluten-free-purity-protocol-listing-of-suppliers-and-manufacturers/

Read more on how to do product research

https://nationalceliac.org/celiac-disease-questions/list-of-gf-foods/

References:

1. National Celiac Association/ Dennis M, Thompson T. Information About Oats. NCA Website. https://nationalceliac.org/nca-stance-on-gluten-free-oats/ Published February 2018. Updated 2021.
2. Thompson T. Oats Are Complicated! Updated Position Statement on Oats from Gluten Free Watchdog. Gluten Free Watchdog Website. https://www.glutenfreewatchdog.org/news/oats-are-complicated-updated-position-statement-on-oats-from-gluten-free-watchdog/ Published March 8, 2021.

Reviewed October 21, 2022.