There still seems to be some confusion swirling around regarding whether or not oats are gluten-free. Hopefully this summary of what I have learned over the years will prove helpful for those of you trying to figure this sometimes confusing world of gluten out!
The short answer:
Oats are gluten-free. In their natural form, they do not contain the protein that harms people with celiac disease and is present in wheat, barley, and rye.
The long answer….
Oats that are not grown in a dedicated field, and processed in a dedicated facility, cannot at this time be considered gluten-free. Crop rotation (4th grade history, anyone?) is said to have been invented/advocated by the first US president George Washington (although it looks like the ancient Romans, as well as some Asian culture came up with it first. For more details, here is a nice Wikipedia article). In general, this is a very good practice, as it prevents the soil in the fields from being stripped entirely of nutrients, and allows for more plentiful harvests. For those of us who are sensitive to gluten, however, this practice has allowed the dreaded “contamination” to infiltrate almost every single batch of oats grown and harvested, as the fields are often alternated between wheat and oats. There is no way to ensure that a few “volunteer” wheat plants don’t pop up during the oat rotation, and make their way into the harvest, and thus into our stomachs.
As if that weren’t enough, oats are also usually processed in the same plants that wheat (aka flour) is processed in. This means that there is a lovely flour/gluten coating on all of the machinery that makes oats and other grains fit to eat (for the rest of the population, anyway).
All that being said, there are some brands of oat growers/processors that grow their crops in dedicated fields, and process them in a dedicated facility. Bob’s Red Mill and Trader Joe’s, are some examples.
There are a very few Celiacs (my little sister included) who are quite allergic to oats, regardless of their gluten status. This is thanks to a protein called Avenin, which in some celiacs mimics the effects of gluten. See this article and this article for some of the super geeky science-y details. I will warn you though, the sample sizes in these studies are quite small, which affects how valid the results of a study are.
So, as you can see, the issue is still a little convoluted. From personal experience, I can tell you that I eat certified gluten-free oats without any problems, as can other Celiacs that I know. My sister, however, cannot, and from my research, I have found that she is not alone.