This post is partly inspired by a small group of ladies that I meet with every monday. When they first suggested we meet over supper time and take turns cooking for one another, I was like "oh crap... I will be poisoned for sure". It's not that I think they can't cook, I just know how tricky it can be. Gluten does not always present itself in an obvious way, and it's taken years (and countless stomach aches) for me to learn which foods to look out for. It's too easy to throw a seemingly innocent sauce or seasoning into a dish without even thinking to read the ingredients first. It's also sometimes hard to spot the gluten in the list if you don't know what you're looking for (eg. barley malt). Oh, and of course there's cross contamination (eg. using a fork to stir wheat noodles then stiring the rice noodles) of utensils, cutting boards and condiments. So anyway, I hope this helps!
Ingredients to watch for:
Wheat, Barley and Rye - I usually ignore the disclaimers saying it may contain traces of wheat because it really doesn't. They're just covering their butts in case by chance something got in and you try to sue them.
Malt - malt flavouring, malt extract, barley malt (maltodextrin is ok - not a barley product)
Flour - assume wheat if it doesn't specify
Gluten - assume wheat if it doesn't specify - if it says something like glutinous rice flour it's ok
Bread crumbs/toasted wheat crumbs
Sauces and Seasonings
Soya Sauce - probably about half of the brands have wheat, you just have to find the right one
BBQ Sauce - some kinds have it and some don't. Read ingredients and look out for sauces make with beer
Worchester Sauce - almost always contains wheat
Seasoning Mixes - read ingredients on these. I have seen seasoned salt that contains flour. Taco seasoning/chilli powder should also be checked. I think most kinds are ok but it's good to double check.
Soup Bases - many brands of dry and liquid soup base contain wheat. You can usually find something that works, but it might take some reading. Sometimes the low sodium varieties may be free of wheat when the full sodium kind has gluten.
Salad Dressing - Ceasar is the big one to watch for, depending on the brand (Kraft is bad). I usually feel pretty safe with italian and ranch. And of course avoid the croutons!
Other Cooking Sauces - prepared teryaki, sweet and sour sauce, etc can be bad so look out.
Pre-Packaged Soups, Cereal, etc
Condensed soups - almost all of these have flour, but I have found that the store brand of my supermarket has a low fat version of mushroom soup that is gluten free (while the full fat version is not)
Ready to eat soup/chilli - while many have flour, you can usually find a couple varieties in each brand that are gluten free. I like the Campbells chunky chicken sausage gumbo and split pea and ham.
Cereal - the big dangerous ingredient in cereal is malt. Most rice and corn cereal contain malt flavouring. And of course many kinds of cereal are made with wheat.
Pasta Sauce - most kinds are ok but the fancier kinds can have flour for thickening.
Chips - most chips are made from corn or potatoes, and therefore seem innocent. Seasoning is the thing you have to watch for. Most doritos are ok, but the Nacho one has wheat in the seasoning. Often BBQ or all dressed potato chips have wheat. Just read.
Licorice - always has wheat flour. I have never seen one that doesn't. Most candy is ok, but for some reason licorice isn't.
Pop corn seasoning - read it!
Chocolate Bars - many do and many don't. Stay away from anything with a wafer (kit kat, coffee crisp, etc). Smarties seem harmless, but they actually have flour in the candy coating (no idea why...) M&Ms are gluten free though!
Beer - there are a few gluten free beers out there, but most is made with barley. Hard liquor tends to be ok because it's distilled.
Tea - most is fine but it can contain barley. I think the gingerbread celestial seasonings one has barley.
Cold Cuts - often kinds like pepperoni and other mechanically separated then squashed back together meats can have flour. Usually basic ham or chicken are ok but look out for any fancy seasonings.
Hot dogs, Sausages, Smokies - many contain wheat. it can take a bit of hunting to find ones that are gluten free.
Burgers - look for all beef. Wheat crumbs are often used as a filler. Check ingredients in restaurants and supermarkets. Or just make your own!
This can be the trickiest part of all.
Crumbs - in the butter, on the counter, on a knife, the list goes on. If you are using a condiment, try to remove the top layer if you see crumbs. It helps if you have your own condiments, utensils and even your own toaster (see bottom of this section).
Stirring Utensils - my husband has done this countless times... stirs his pot of noodles then uses the same fork for mine. Try to keep everything as seperate as possible and don't reuse cutting boards you've cut wheat products on without washing them first.
Dips - even if the dip is technically gluten free, it's best to put some in a separate container for yourself in case someone dips a cracker or bread in it while you weren't looking.
Baking pans and sheets - just make sure these are washed well. You can even have a separate pan for your gluten free baking.
Plating - make sure to keep gluten free stuff on a different dish than wheat-containing products. Many people will react even with that little bit of contact.
Toaster/Microwave - make sure you have your own toaster (or at least your own side of the toaster) for your gluten free bread. Also, make sure to put your food on a plate before microwaving because who knows what kind of residue has been left in there...
This list is not exhaustive. Please feel free to contribute to my list with your comments. I will try to update these lists as I think of more gluten dangers. Good luck!