Asking what “gluten-free” food is actually free of gluten might sound like a trick question, but it isn’t. While there certainly inherently gluten-free foods, some that you might think are free of gluten are not, usually because they have been contaminated with gluten from another food source.
You have to consider the type of food when trying to answer this question. If you boil an egg and eat it without adding anything else, you will not be taking in any gluten. If you peel and eat a banana, or drink a glass of unflavored milk, you will not be getting any gluten. But if you are talking about food that has been processed, you cannot assume anything.
There are cereal grains that are believed to be gluten-free, including, for example, sorghum, millet, corn and rice (many varieties). Flours can be made from various beans and nuts, including chickpeas and almonds. None of these contains gluten naturally.
However, many of the companies that package these grains, make products like bread from them, or grind them into flour do so on shared equipment that has been used to process wheat (or rye or barley). Similarly, they can process these foods in a facility that handles wheat. In these cases, anywhere from a little to a lot of gluten can get into the final product.
When you are looking at what you think should be a gluten-free product, you need to look at the label carefully. You may find out what you need to know. If it lists wheat, rye or barley, or it says it has gluten as an ingredient, obviously you know it is not gluten free.
While there is no law forcing manufacturers to do so, many will say if a product has been manufactured on equipment shared with other foods or in a facility where other foods are processed. People with gluten intolerance should not eat anything that has a package warning of this type.
Gluten-free products should state that they have been tested to a certain standard of low amounts of gluten. Here we come to an area that has frustrated people with celiac disease in the United States. The FDA proposed regulations of gluten content and labeling in 2007, but other than eliciting more comments and collecting more data, they do not seem to have taken steps to actually using the proposed regulations.
Packages of processed food labeled gluten-free would have to have less than 20 ppm of gluten. This is a level that can be determined by existing tests, and is also a level that is safe for most people with celiac disease.
In the absence of any enforced regulation, there are voluntary ways for manufacturers to get their products stamped gluten-free. The Gluten Intolerance Group® or GIG® offers certification, via the Gluten-Free Certification Organization. This group inspects products for gluten, accepting those only with gluten levels less than 10ppm as gluten free. Certification is done on a yearly basis, with inspection done at the production facility, as well as testing of the product. Different companies and products require different numbers of tests.
The tests used can determine that there is less than 10 ppm of gluten (5 ppm gliadin) as well as similar proteins from barley and rye. There are no tests that can go down to zero. Less than 10 ppm is the best that a test can do at the current time, and is twice as sensitive as the 20 ppm suggested by the FDA. Any foods certified by the GIG would meet FDA standards.
In order to be as sure as possible about the foods certified, GFCO uses two different ways to measure amounts of gluten. Both of these tests have weaknesses, but together give as accurate a picture as possible.
At the end of the process, a product can have a designation of Gluten Free made by the GFCO. This is something you can look for as a consumer. You can also go to their website and select products from a drop-down menu to see if they have been certified (http://www.gfco.org/products.php).
There are stores that carry gluten-free products as well as websites that sell them online. If you find breads or cereals or flour that says it is gluten free and you are doing well eating these products, you should probably continue to use what works for you. If you have just been diagnosed with CD, looking for the GFCO gluten-free logo would be a good way to find gluten-free foods.