Uncontaminated natural oats are naturally gluten free and are a great source of fiber. When you are gluten free, it is important to make sure that the oats that you use are certified gluten free. There are many times during the growing and production of oats that they can become contaminated by wheat.
Oats are commonly grown in the same or neighboring fields as wheat and can also be harvested and transported with the same equipment as wheat. They are also often processed in the same plants as wheat.
There are now certified gluten free oat products that are widely available in grocery stores. Look at nutrition label as well as the packaging. If a product is certified gluten free, the packaging will have a certification stamp on it or it will say that it is a gluten free product.
As always, read labels and packaging carefully.