Celiac.com 08/31/2016 - Oats are traditionally one of the more commonly contaminated gluten-free grains on the market.
According to Gluten Free Watchdog, "gluten-free" foods made with oat ingredients are more commonly contaminated than foods made with other "gluten-free" grains. In light of their survey results, people with a high sensitivity to gluten might want to consider taking some extra steps to make sure their oats are truly gluten-free.
1) Make sure you are sourcing oats from a supplier of purity protocol oats, such as gluten-free Harvest, Avena, or Montana Gluten-Free. Currently, Gluten Free Watchdog does not recommend any of the commercial suppliers of mechanically and optically sorted oats, such as Grain Millers or LaCrosse Milling.
2) Ask for test results. Regardless of where you source oats, ask your supplier to provide you with test results, including how frequently oats are tested and what assay is used for testing.
3) Test the oats yourself. There is no such thing as too much testing. If you really want to be sure, you can send samples of oats to a third party lab for testing using the sandwich R5 ELISA and cocktail extraction. Labs include Bia Diagnostics and FARRP.
Read more at Gluten Free Watchdog.