What is Gluten Cross-Contamination?

If you’ve been gluten-free long enough, you know that gluten cross-contamination is no laughing matter. If a crumb of gluten comes in contact with your food, it can create a cascade of painful symptoms in people with celiac disease and gluten sensitivity. In this article, I define gluten cross-contamination and how to avoid it. This article contains affiliate links. Please see my disclosures.

Gluten cross-contamination can occur anywhere, from gluten-free food being cooked in the same deep fryer used to cook gluten-y food, as well as a chef not washing his hands between preparing a gluten-free sandwich and a gluten-y sandwich.

Unfortunately, gluten happens, and cross-contamination is more often than not why so many people with celiac disease and gluten sensitivities get sick when eating out. Gluten is a protein found in wheat, rye, barley, and sometimes oats, and it’s hidden in many foods.

In this article, I discuss the definition of gluten cross-contamination, where gluten lurks, and how to protect yourself from getting glutened by it.

For more detailed information on gluten cross-contamination, watch the following video presentation I created on the topic.

What is Gluten Cross Contamination?

Gluten cross-contamination occurs when a food deemed “gluten-free” comes in contact with gluten somewhere along the way. Below are several sources of potential gluten cross-contamination at restaurants and at home:

(1) Unclean Hands

A chef might handle a loaf of bread, then handle the lettuce without washing his hands. Crumbs from the bread are then transferred from the bread to the salad. Good hand washing is essential to preventing the spread of gluten crumbs.

(2) Surfaces

A chef might cut a steak marinated with soy sauce, which contains gluten, and then use that same cutting board and knife to cut a gluten-free piece of steak. This can also happen when pots and pans are not properly cleaned and used to prepare gluten-free and gluten-full meals.

(3) Meal Delivery

When the waiter brings the gluten-free meal to the table, he might stack it alongside the other meals. Bits of gluten from the other dishes can leak onto your meal. This scenario happened to me at PF Chang’s as I watched the sauce from one dish drip onto my gluten-free meal.

(4) The Toaster

While a restaurant might offer you a piece of gluten-free toast to go with your omelet, the staff might also toast the gluten-free slice of bread inside a toaster used to toast wheat bread. At home, you must use a dedicated gluten-free toaster as well. (Researchers looked into whether or not shared toasters posed a cross-contamination risk. Read my article, Do Convection Ovens, Toasters, Microwaves, and/or Air-Fryers Pose a Gluten Cross Contact Risk?, to learn more.)

(5) The Colander

Gluten-free pasta should not be strained using the same colander used to strain regular pasta. This is why at home, it’s essential to have a dedicated strainer.

Restaurants can be careless in this task, and I know first-hand just how scary this can be. In fact, this exact scenario happened to my pasta dish at the Cheesecake Factory.

Look closely at the following photo to spot a stray strand of angel hair pasta floating in the middle of my gluten-free fusilli pasta dish.

Nima Sensor found gluten in Evelyn's gluten-free pasta dish at Cheesecake Factory

(6) The Deep Fryer

The deep fryer is a hotbed for gluten cross-contamination inside restaurants. For example, if a restaurant serves gluten-free chicken fingers, they might cook them in the same oil used to cook regular chicken fingers. If so, chances are bits of the breading from the chicken fingers have attached themselves to the gluten-free chicken fingers.

Furthermore, French fries, while naturally gluten-free, can also become contaminated with gluten bits in the deep fryer if the same deep fryer is used for cooking any breaded items.

Therefore, when ordering any deep-fried foods below, you must ask your server if the restaurant has a dedicated gluten-free fryer. If it doesn’t, skip fried foods altogether when eating out:

French fries
Fried chicken
Fried appetizers
Corn or tortilla chips
Corn dogs
Onion rings
Breaded Chinese food dishes (sesame chicken, sweet and sour chicken)
Tempura
Chicken fingers
Chicken wings
Calamari
Donuts
Fritters
Egg rolls
Falafel
Fish sticks
Wontons

This list is by no means exhaustive. It includes only the most common deep-fried items that could become affected by gluten cross-contamination.

(7) The Waffle Iron

That gluten-free waffle presented to you may have been prepared with gluten-free batter, but if it was cooked in the restaurant’s only waffle iron, the same one used to cook all waffles, then your waffle will surely come in contact with gluten. At home, invest in a dedicated gluten-free waffle iron.

(8) The Griddle

Gluten-free pancakes are often cooked on a griddle, which could be the same griddle surface used to cook gluten-free pancakes. The same goes for hamburgers when the restaurant also toasts the buns on the same griddle using the same spatula. This is an example of gluten cross-contamination galore!

(9) The Grill

The griddle is often cross-contaminated with gluten bits, but the same goes for the grill. Meats marinated with soy sauce can easily contaminate the cooking surface of a grill, rendering your “gluten-free” meat no longer gluten-free. Remember, heat does not kill gluten! At home, clean your grill or use grill mats for cooking gluten-free foods.

(10) Bulk Bins

Bulk bins contain various products, from quinoa and rice to oats and barley. People often use the same scooper to scoop up all products, contaminating the bins and products. Read my article, 5 Hidden Sources of Gluten at the Grocery Store, for other sources of hidden gluten.

(11) Buffets

Buffets are cross-contamination cesspools. People use the same tongs to grab gluten-free items as they do to grab gluten-y items. Drips of gluten-y salad dressing fall into the gluten-free salad dressing. It’s a mess! Be very cautious of cross-contamination at buffets, or skip them altogether. This warning also goes for the toppings bar at frozen yogurt joints.

(12) The Mixer

Some desserts are mixed in an electric mixer that may have also been used to mix wheat flour-based desserts. The flour bits often make their way up into the crevices of the mixer and then down into the gluten-free batter. Instead, opt for handmade desserts made in a dedicated gluten-free bakery. Have a dedicated gluten-free mixer at home if you plan to bake a lot.

Tips for Avoiding Cross Contamination

While there’s no foolproof way to know for sure if your food has been cross-contaminated with gluten, especially when you eat out and have trusted the meal prep process to another person, there are a few precautions you can take to avoid it from happening:

(1) Be firm with your server

There are many trendy gluten-free dieters out there. Tell him you’re not one of them. Ask him to take your request seriously. Speak with the manager if you feel uncomfortable with your server’s ability and knowledge about this process.

(2) Look for clues

Some restaurants use different colored plates or toothpicks to identify gluten-free items. These clues can help you know how safe your dish was prepared.

The picture below shows that Red Robin marks its gluten-free dishes with a purple toothpick.

Purple-stick-in-burger-means-its-gluten-free-at-Red-Robin

(3) Ask for your dish to be served separately

Ask your server to bring out your dish on a separate tray from everyone else’s food.

(4) Ask your server how he knows it’s gluten-free

Your server may tell you that he picked up your meal from a specific location, verified it was gluten-free with the chef, knows that the gluten-free pancakes look different from regular pancakes, etc. See what he says and use his response as clues to guide you in making an educated decision about whether or not you feel safe eating something.

(5) Test your food for hidden gluten

The Nima Sensor, Allergy Amulet, and Glutrust are portable gluten-detecting devices that enable you to test your food for hidden gluten. While you can only test a small piece of your food, if you smear it across your dish before placing it in the test capsule, you might be able to pick up any potential gluten cross-contamination.

Related Reading: Watch how the Nima Sensor saved me from eating this pancake at Snooze!

(6) Eat as naturally gluten-free as possible

While an egg omelet can still be cross-contaminated, it’s more likely that the pancakes and toast will come in contact with gluten along the way. Try to order as naturally gluten-free as possible when eating out to avoid cross-contact snafus. Read 10 Naturally Gluten-Free Foods Every Celiac Should Be Eating.

(7) Avoid pizza, no matter how tempting

Along those same lines, it’s important to note that pizza is one of the most unsafe dishes you can order, even if it’s gluten-free pizza. In fact, all five of the top pizza chain restaurants say they do not recommend their pizzas for people with celiac disease or gluten intolerance.

Gluten-free pizza is often prepared along the same assembly lines and cooked in the same ovens as regular pizza. If you’ve made pizza before, you know that flour is everywhere in a pizza kitchen, even airborne.

If you enjoy eating pizza, check out my article that ranks the best frozen gluten-free pizzas (I tested every pizza for hidden gluten, too) or my homemade pizza crust recipe.

Words of Encouragement

Eating out is never easy, but it’s essential to living life. Use this information to be smart about eating out and do your best to protect yourself from accidental gluten exposure.

You can learn more tips about eating out safely while following a strict, gluten-free diet in my book, The Ultimate Guide to Eating Out Gluten Free.

Download my free Gluten-Free Safe Dining Card and show this card to your server when you eat out. He’ll know you’re serious about getting a gluten-free safe meal.