Bob's Red Mill, GF Harvest, Montana Gluten-Free, Glutenfreeda Foods and Holly's Oatmeal are several brands that offer gluten-free oats. Although oats are inherently gluten-free, they are usually cross-contaminated during processing with wheat, barley or rye.
While these brands certify that they meet the FDA's requirement that gluten-free products contain less than 20 parts per million of gluten, some people with celiac disease still have reactions. The exact cause of this is not determined, but some people with celiac disease or non-celiac gluten sensitivity also react poorly to avenin, a protein found in oats. Some celiac disease sufferers are affected by different oats varieties or are more sensitive to them.
Cross-contamination of oats also occurs during the growing process. Oats are grown alongside wheat, barley and rye, the three primary carriers of gluten, before being processed through the same equipment. Pure oats are usually tolerated by adults and children with celiac disease, but doctors still recommend eating only moderate amounts of oats. People who have been recently diagnosed and have not seen a full cease in symptoms should not eat oats at all until their symptoms are manageable. Doctors also recommend returning for regular blood tests to make sure the gluten-free oats are not triggering an immune response over time.