Pure oatmeal does not contain gluten. However, most oatmeal brands on the market today are not pure they contain oats that have been cross-contaminated with a tiny bit of wheat, barley and/or rye. Since those grains do have gluten in them, that cross-contamination makes most oatmeal brands unsafe on the gluten-free diet.
For example, Quaker Oats states on its website that it cannot guarantee its oatmeal is gluten-free.
It's possible to grow pure oats, and companies selling certified gluten-free oatmeal are using oats that do not have any gluten cross-contamination. Those should be safe for the majority of people with celiac disease and non-celiac gluten sensitivity.
- For more on this, see: I can't eat gluten. Should I try oats?
So Which Brands Are Safe?
Fortunately for those who can tolerate oats, there are a variety of different gluten-free-certified oatmeals on the market:
Bob's Red Mill produces three different types of gluten-free oatmeal, including quick-cooking oats, rolled oats and steel-cut oats. Bob's tests for gluten down to 20 parts per million. Make sure you purchase only gluten-free labeled oatmeal Bob's has several that are not gluten-free.
GF Harvest is a celiac family-owned business in Wyoming. The company grows its own oats and performs extensive testing to make certain its fields remain uncontaminated, including testing the seeds it uses down to 3 parts per million. GF Harvest holds gluten-free certification along with organic and Kosher certifications. Products include organic gluten-free rolled oats and regular gluten-free rolled oats, which you can use to make gluten-free oatmeal.
Glutenfreeda Foods offers four different types of certified gluten-free oatmeal, including apple cinnamon, maple raisin, banana maple and natural. All contain flax meal in addition to gluten-free oatmeal. Glutenfreeda sells its products online and in some specialty stores.
Holly's Oatmeal aims for the purest possible oatmeal the company tests its oats to make sure they contain less than 5 parts per million of gluten. Holly's makes gluten-free oatmeal in two flavors: plain and cranberry. Since the company also sells non-gluten-free oatmeal, make sure you only purchase products in the blue boxes. The oatmeal is available online and in some stores, including Whole Foods.
Montana Gluten-Free works directly with farmers to make certain the oats it sells are not cross-contaminated with gluten. The company offers gluten-free oatmeal in two sizes: 3 lbs. and 7.5 lbs., both of which you can purchase at the Montana Gluten-Free website.
Note that other companies that sell gluten-free products (Arrowhead Mills, among others) also produce oatmeal that's not certified gluten-free be very careful to check labels, and assume a product isn't safe unless it's specifically marked as gluten-free oatmeal.
Gluten-Free Oatmeal May Not Agree With You If You Have Celiac Disease
To make things even more complicated, a small percentage of people with celiac disease and gluten sensitivity also react to avenin, the protein found in oats, which means they need to add oats to their list of prohibited grains.
It's not clear how many people with celiac disease also react to oats some estimates are in the range of 10% to 15%, but research is ongoing. In addition, there's evidence that some types of oats are more toxic than others to people with celiac disease.
If you have celiac or gluten sensitivity, the only way for you to determine if you react to oatmeal is to try some (start with just a couple of spoonfuls) in its pure, gluten-free form there is some anecdotal evidence that people who are more sensitive to gluten also react more frequently to oats, but there's no research to prove it (see more on sensitivity levels in my article How Much Gluten Can Make Me Sick?).
Therefore, if you're a diagnosed celiac, you should consult your physician first and then proceed very cautiously when adding gluten-free oatmeal to your diet. If your celiac disease symptoms return, stop eating the gluten-free oatmeal immediately.