13 surprising foods you didn't know contained gluten

Not all oats are created equal, and not all oats are gluten-free. The biggest problem when it comes to oats, or oatmeal, is contamination, which can happen in the field (if oats and wheat are grown side-by-side) or during processing (if the oats are processed on equipment that also processes wheat).

Look for oats with a certified gluten-free label, and beware of molasses- and brown sugar-flavored varieties, which can sometimes contain wheat-bearing caramel coloring.

As the name implies, soy sauce is made with soybeans that are steamed, fermented and aged, often with the addition of wheat for aroma and a bit of sweetness.

When shopping for soy sauce, opt for labels that specifically say gluten-free.

There are two reasons why ground spices like curry powder, turmeric, paprika, and cinnamon might contain gluten: They were either contaminated while in the factory, or the manufacturer added a little flour to them later to prevent caking.

Most herbs and spices are safe, however, especially if they're fresh.

Most chocolate is safe to eat if you can't have gluten, but some may contain crispy bits or caramel coloring that could contain gluten, or may be processed on equipment that also handles wheat-based ingredients.

Cocoa powder, hot cocoa mix, and chocolate sprinkles may also not be completely free of gluten.

It's not just beer and ale — many varieties of alcohol have gluten in them, including whiskey, bourbon, and rye.

Cider, wine, tequila, and rum are almost always safe to drink for people who can't have gluten, as are gluten-free beer brands like Omission and New Planet.

Cucumbers? Gluten-free. Pickles? Not necessarily, and not if they're pickled in malt vinegar. Malt vinegar is made directly from ale, which itself contains wheat.

If your pickles are brined in white vinegar, or any other wheat-free vinegar, however, you're in the safe zone.

Unless it's processed on contaminated equipment, all rice is gluten-free. However, it's the California roll that celiacs should worry about, which is made with imitation crab meat — an assortment of different seafoods and fish mixed with starch.

Other kinds of fish are perfectly fine, but again, make sure you use proper gluten-free accoutrements (soy sauce and even some kinds of wasabi).

Cold cuts, including hot dogs and sausages, can become contaminated with gluten when they're being processed. Some may also contain wheat-based fillers.

But not to worry, it's perfectly fine to eat grain-fed meat.

Seitan, and many other vegan or fake-meat products, are made primarily of gluten (one nickname for gluten is "wheat meat," since it's a protein that comes from wheat).

Many gluten-free vegans and vegetarians have developed recipes for seitan sans gluten.

Gravy is commonly made by taking the drippings from chicken, turkey, or other roasted meat and thickening them with flour or cornstarch.

Gravy made with cornstarch is fine for folks with celiac; gravy made with flour is not.

Not all fried foods have gluten in them, but the ones that are battered (in beer, flour, breadcrumbs, etc.) and then fried could be problematic.

As long as the frying oil hasn't touched wheat, other fried foods are harmless.

Just because a grain is labeled "whole" doesn't mean it's gluten-free. Couscous, spelt, barley, and kamut are all whole grains that contain gluten.

Safe-to-eat whole grains include buckwheat, quinoa, flax, millet, and sorghum.