A food label should contain all the information you need to figure out if that food is safe on the gluten-free diet.
You need to avoid:
The Food Allergen and Consumer Protection Act says labels have to list the top eight allergens, including wheat, in plain English whenever they are an ingredient in packaged foods regulated by the FDA.
That means you will never have to guess whether some strange ingredient is made from wheat. If wheat is used, the label will tell you. (Meat, eggs and poultry are regulated by the USDA, which is not covered by the allergen labeling law. However, the USDA has advised food processors that it expects them to declare all sources of allergens on their labels.)
If a food contains wheat, you will find "wheat" in the ingredients list or the phrase "Contains wheat" immediately after the ingredients list. Some food companies do both.
Rye and Barley
Rye and barley are not covered by the allergen label law. However, rye is not used that often in foods, and when it is the label usually says so.
Barley is more common and can be more difficult to recognize on a food label. It can be listed as barley, barley malt or just malt. Although rare, barley malt is sometimes simply listed as "flavoring."
But food companies are becoming more aware of the gluten-free diet. Although they aren't required to, some companies list the source of all gluten-containing ingredients, including barley, on their labels.
Oats present a different food labeling problem. Studies show oats do not contain gluten protein that is harmful to those who follow the gluten-free diet. However, oats are often contaminated with wheat so if you see them in an ingredient list it is highly likely the product is not gluten free. The gluten-free diet only allows oats specifically grown, processed and labeled for the gluten-free market. Specially processed oats are usually not used as an ingredient in mainstream foods and are sold mainly as gluten-free oatmeal.
In addition to the ingredients list, you may find advisory labels on a food package. Advisory labels are not regulated and companies use them voluntarily. They give consumers more information about the possibility that a food could be cross-contaminated by an allergen during processing.
Some say "May contain Wheat." Others say "Produced in a plant that also produces products made with wheat" or "Produced on equipment that also produces products that contain wheat." You have to decide whetheryou want to include foods with these labels in your diet.
A final note on label reading - you must always read the label on a packaged food, even if you buy it regularly. Ingredients can change and reading the label is the best way to be sure you know what is in your food.