You need to avoid any food that contains the protein from wheat, rye, or barley. Here is a list of these foods:

• Atta (chapatti flour)
• Barley (flakes, flour, pearl)
• Beer, ale, lager
• Breading and bread stuffing
• Brewers yeast
• Bulgur
• Communion wafers
• Couscous
• Croutons
• Dinkel (also known as spelt) *
• Durum *
• Einkorn *
• Emmer *
• Farina
• Farro or Faro (also known as spelt) *
• Fu **
• Graham flour
• Hydrolyzed wheat protein
• Kamut *
• Malt, malt extract, malt syrup and malt flavouring
• Malt vinegar
• Malted milk
• Matzoh, matzoh meal
• Modified wheat starch
• Oatmeal, oat bran, oat flour and whole oats ***
• Pastas
• Rye bread and flour
• Seitan ****
• Semolina
• Spelt (also known as farro or faro, dinkel) *
• Triticale
• Wheat bran
• Wheat flour
• Wheat germ
• Wheat starch

* These are all types of wheat

** Fu is a dried gluten product derived from wheat that is sold as thin sheets or thick round cakes. Used as a protein supplement in Asian dishes such as soups and vegetables.

*** Oats are contaminated with wheat and barley, unless they are specially grown, harvested and processed.More information.

**** Seitan is a meat-like food derived from wheat gluten used in many vegetarian dishes; sometimes called “wheat meat”.

 

Here are more questionable items

Source: Adapted with permission from Gluten-Free Diet: A Comprehensive Resource Guide 2008 by Shelley Case, Dietitian.