Gluten is a protein extracted from wheat and other grains by washing the starch out of the grain. People who cannot properly digest this protein suffer from celiac disease, an inflammatory condition of the small intestine. Those who suffer from this condition must consume only gluten-free foods, which don't include wheat, rye, or barley.
While people who follow a gluten-free diet cannot consume anything made of wheat, rye, or barley — including most commercially prepared cakes and pastries — there are other grains and flours that do not contain gluten. These include buckwheat, corn, potato flour, rice, arrowroot, and soy. More and more cakes, cookies, and cereals are available that are made without gluten, making them suitable for everybody.
There's been a lot of debate as to whether people who do not eat gluten can eat oats. Pure oats are a gluten-free food, but it may be difficult to find them, as most come in contact with wheat at some point in the manufacturing process, and they are therefore considered "contaminated."
Most dairy products are gluten-free, with the exception of some cheese spreads, some flavored milks, and custards. Meats are gluten-free foods unless they prepared with breading or are processed, such as in the case of sausages. Meat pies, frozen meats, and chicken broth usually contain gluten in some form or another, and they are best avoided.
The same is true of fruits, vegetables, and nuts. Unless sauces, starches, or thickeners have been added, all of them are naturally gluten-free foods. It is becoming more and more common to add wheat flour to canned fruits and vegetables, however. This is used as a processing aid or a binder and is not always mentioned clearly on the label. To avoid this, shoppers should only buy well-known brands that include a detailed label or buy only canned vegetables that are clearly marked as gluten-free.
Except malt vinegar, almost all condiments are gluten-free foods. This includes tomato paste, tahini, maple syrup, and many salad dressings. Herbs and spices, unless mixed with artificial flavorings that contain gluten, are also acceptable.
When it comes to beverages, beer should be avoided unless it is specifically labeled as gluten-free. Most other alcoholic and non-alcoholic drinks don't contain gluten, although those made from barley or malt do. Many processed foods, such as soy sauce and pie fillings, can include this protein without specifying so in the label. People who do not eat gluten should try to use fresh ingredients and be more aware of what's in the food they're eating.