The FDA has approved the gluten-free label standards below! Still, look for the seals if you want a product that has been certified by an independent organization.
In the 2013 law, the FDA defines a product as gluten-free if it does not contain the following: wheat, rye, barley, or any hybrid of these grains; ingredients such as wheat flour that have not been processed to remove gluten; or any item made up of more than 20 parts per million of gluten.
Your best bet when buying something that comes in a bag, box or can is to look for a gluten-free certification badge. Manufacturers pay for this certification and go through regular inspections and auditing of their facilities
Products labeled with this logo are certified gluten-free by the National Foundation for Celiac Awareness and have 10 parts per million or less of gluten.
Products labeled with the logo below are certified gluten-free by the Gluten Intolerance Group and have less than 10 parts per million of gluten.
The Celiac Sprue Association also certifies gluten-free with a threshold of 5 parts per million. Celiac Sprue Association
If the product does not show a certification badge the next step is to look for a statement on the packaging that it is gluten-free. This is no guarantee but it is one step. I feel comfortable if it states that it is produced in a dedicated gluten-free facility. The certification is a big expense so many smaller facilities chose to forego it.
Next read the ingredients. The first place I look in the ingredients is at the end. A 2004 law requires that wheat be clearly stated on the label. Labels may say “contains wheat” or “manufactured in a facility that also processes wheat” or “manufactured on the same equipment that processes wheat.” The latter 2 mean that wheat is not an ingredient but the product may have traces of wheat. For someone with Celiac Disease or a severe gluten allergy or intolerance these products are not safe.
Here’s where it gets a little more complicated. There are still barley and rye to consider. Rye almost never hides as anything other than rye. But barley does hide under several aliases and there are no current regulations for barley. Malt, malt syrup, and brewers yeast are just a few ingredients to look for. Maltodextrin is ok as long as it is not derived from wheat and labeling will indicate if that is the case.
For some more specifics on how to shop for grains check out my article Grains, Grains Gluten-Free or Not?