Gluten in Oats Due to Cross-Contamination

Although it has been found that some types of oats have a naturally occurring level of gluten, or a protein that closely resembles gluten, in general oats are believed to be a naturally gluten-free product. Unfortunately, by the time it gets from the field to your plate, it mostly likely is no longer free of gluten. The main reason for this is due to cross-contamination of the oats with other, non-gluten-free crops during harvesting and processing.

Wheat, barley, and rye are the non-gluten-free crops that oats typically become cross-contaminated with. The cross-contamination can happen in a number of different ways from the time the oat seeds get placed in the ground for growing to when the oats are placed in containers for sale.

Farmers usually rotate growing oats in their fields with crops of wheat or barley. This means that during one summer the field will be filled with a crop of only oats. Then, the next summer the same field will be filled with a crop of wheat or barley. In the summer following that, oats will be planted again in the same field. Although only oats are in the field during this time, some kernels of the wheat or barley gets left behind from harvesting the previous year. This is where cross-contamination of the oats with the gluten-containing wheat or barley can occur.

Not only are crops of oats rotated with crops of wheat or barley, but they are also sometimes grown in fields right next to each other during the same season. This can cause cross-contamination because of weather conditions and harvesting methods. Wind can blow kernels of wheat or barley into the fields of oats while the crops are still growing. During harvest time, if the wheat or barley is harvested first, the machines can throw pieces and dust of the wheat or barley onto the oats.

When it comes to processing and transporting of the oats, cross-contamination can occur because of the machines and trucks used at the mills. Oats are often harvested and processed using the same equipment used to harvest and process gluten-containing wheat, barley, and rye. Typically, farmers, mills, and processing plants do not clean the machines or trucks between loading crops of wheat, barley, or rye and crops of oats.

Currently, the FDA does not regulate the use of the term "gluten-free" on food labels. Manufactures can claim that their product is "gluten-free" and place this on their label without actually testing for gluten levels. The FDA is in the process of adopting a standard that products must meet in order to be considered gluten-free, but it still would not require the product to be completely free of gluten. The standard would allow food products containing a total of 0.002% of gluten or less to be labeled "gluten-free".

In a study done of 134 oat products collected from the United States, Europe, and Canada, only 25 were found to have undetectable levels of gluten. Most of the other 109 oat products were found to be contaminated with mixtures of wheat, barley, and rye.

There are oat products on the market that claim to be "gluten-free", and have been specially processed to bring them within safe levels for people who cannot eat gluten. Even so, if you are sensitive to gluten, or are following a completely gluten-free diet, you should be aware that these "gluten-free" oat products might still contain some levels of gluten. The safest choice for people on a gluten-free diet is to eliminate oats from your diet completely.