Gluten cross-contamination is no laughing matter and can greatly impact the health of someone following a strict, medically necessary gluten-free diet. In this article, I explain cross-contamination and the 10 most important things you need to know about it when you have celiac disease or non-celiac gluten sensitivity. This article contains affiliate links. Please see my disclosures.
If you’ve been in the gluten-free community long enough, chances are you’ve heard the “cross-contamination” buzzword.
Gluten cross-contamination occurs when naturally gluten-free food comes in contact with food that contains gluten, a protein found in wheat, rye, barley, and sometimes oats (more on oats later), rendering the food no longer safe for someone on a gluten-free diet to eat.
People with celiac disease know that even a crumb of gluten can set off a cascade of symptoms in their body, making them run for the toilets and/or fueling inflammation at the weakest link in their genetic chain, whether it be their skin, thyroid, digestive system, brain, etc.
In people with celiac disease, a genetic autoimmune disease, the immune system mistakenly attacks and damages the small intestine every time gluten is present.
Such damage can lead to many painful and annoying symptoms that, if not managed, can lead to more serious conditions like additional autoimmune diseases, cancer, and even early death.
This is why people with celiac disease are stringent in their avoidance of all gluten, as even a small crumb of gluten will impair healing and allow disease to ensue.
People with gluten intolerance also must be mindful of gluten cross-contamination. Gluten leads to chronic inflammation, which in turn leads to chronic, painful, and annoying symptoms that significantly impair their quality of life.
If you’re following a medically-necessary gluten-free diet due to a celiac disease or gluten intolerance diagnosis, then you need to know these 10 important things about cross-contamination.
(1) Cross-Contamination Can Occur Anywhere
Few places in the world are free from gluten cross-contamination, and cross-contamination will always be a concern unless your home is a dedicated gluten-free home or you eat exclusively at dedicated gluten-free restaurants.
Sources of cross-contamination that the gluten-free community must be aware of include but are not limited to the following:
Unclean Hands: A chef might handle a loaf of bread, then handle lettuce without washing his hands. Crumbs from the bread are then transferred to the salad. Good hand washing is essential to preventing the spread of gluten crumbs.
Surfaces: A chef might use a cutting board to slice 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.
The Waffle Iron: That gluten-free waffle presented to you at a restaurant was likely prepared in the restaurant’s only waffle iron, which is the same one used to cook gluten-full and gluten-free waffles. Avoid waffles at restaurants and invest in a dedicated gluten-free waffle iron at home.
The Griddle: Gluten-free pancakes are often cooked on a shared griddle used to cook regular pancakes. The same goes for hamburgers and buns toasted on a shared griddle using the same spatula.
The Grill: The grill is often beaming with stuck-on gluten bits that are impossible to remove, no matter how hard you clean it. Heat does not kill gluten! Learn more about cooking food on a shared grill in my article, 13 Tips For Surviving Summer Cookouts When You’re Gluten-Free.
The Ice Cream Scoop: Ice cream scoops spread cross-contamination when they’re used to scoop gluten-y cookie dough ice cream and then used to scoop gluten-free vanilla ice cream. Soft-serve is safer since there’s no scooping involved.
The Electric Mixer: When desserts are mixed in a shared electric standing or handheld mixer, they can quickly become contaminated with bits of flour. Flour bits get stuck in the crevices, and then they’re knocked into the gluten-free batter.
Use a dedicated mixer at home, avoid desserts prepared in a shared mixer at restaurants and friends’ houses, and support your local gluten-free bakery when you’re craving a sweet treat.
(2) The Deep Fryer is a Top Source of Cross-Contamination
The deep fryer is a hotbed for gluten cross-contamination at restaurants.
For example, a restaurant may use that same fryer to cook naturally gluten-free French fries and gluten-y chicken nuggets. This means the French fries are coming in contact with gluten and thereby rendering your French fries no longer gluten-free.
Ask your server if the restaurant has a dedicated gluten-free fryer. If the fryer is shared, skip all fried foods, including but not limited to:
- Breaded Chinese food dishes (sesame chicken, sweet and sour chicken)
- Chicken fingers
- Chicken wings
- Corn dogs
- Corn or tortilla chips
- Egg rolls
- Fish sticks
- French fries
- Fried chicken
- Fried appetizers
- Onion rings
(3) The Toaster May [Not] Be a Source of Cross-Contamination
While a restaurant might offer you a piece of gluten-free toast to go with your omelet, the staff might toast a gluten-free slice of bread inside a toaster used to toast wheat bread. You might also be using a shared toaster at home.
While most people with celiac disease or gluten intolerance agree it’s wise to use a separate toaster to toast gluten-free bread, and I highly recommend having a dedicated toaster oven at home, it’s important to understand that the science doesn’t fully support this recommendation.
Researchers tested the level of cross-contamination found on gluten-free bread toasted in shared toasters inside a busy hospital cafeteria. The toasters had visible gluten-containing crumbs and were not cleaned between uses.
Surprisingly, researchers didn’t find gluten transfer from a shared toaster to be above the 20 ppm threshold, the amount of gluten a product can contain to be labeled gluten-free.
While it’s nice knowing there is only a small risk of cross-contamination in a shared toaster, it’s important to remember that this is a one-time limited study in a controlled scenario.
Would these results be replicable in a busy kitchen environment, say a popular brunch restaurant? The answer to this question is unknown, and it’s why many gluten-free experts recommend avoiding shared toasters or using a protective toaster bag.
(4) Cross-Contamination Affects People with Gluten Intolerance Just as Much as People With Celiac Disease
It makes me sad when people with gluten intolerance don’t think they have to take their gluten-free diets as seriously as people with celiac disease.
Isn’t gluten intolerance a REAL condition with real medical consequences?
I hear stuff like, “I don’t have to worry about cross-contamination because I only have gluten intolerance, not celiac.”
In the same breath, these people with “just” gluten intolerance want their disorder to be taken “just” as seriously as people with celiac disease. They also experience terrible symptoms when they eat gluten, and some of my gluten-intolerant friends report having worse reactions to gluten than people with celiac.
The truth is that low-gluten diets don’t work, and cross-contamination affects anyone on a gluten-free diet, not just those with celiac disease.
(5) Pasta Water Cross-Contamination Is Real
Ordering pasta at a restaurant is like playing Russian Roulette. It’s why, in my ebook, The Ultimate Guide to Eating Out Gluten-Free, I recommend against ordering pasta at restaurants.
Too often, restaurants cook gluten-free pasta in the same water as regular pasta, and I know first-hand how scary this can be because it happened to me at the Cheesecake Factory.
Look closely at the following photo to spot a stray strand of angel hair pasta floating in my gluten-free fusilli dish. Gee, I wonder how that got there?!?
(6) The Colander Poses High Cross-Contamination Risk
Many people will tell you that cleaning a colander well with soapy hot water will ensure it’s clean for straining both regular and gluten-free pasta, but I’m not buying it.
When I look at my wirey colander, I see bits of leftover food stuck in the crevices.
At home, I recommend using a dedicated strainer to strain gluten-free pasta. It’s better to be safe than sorry.
(7) Bulk Bins Are Cross-Contamination Central
Bulk bins, which can contain beans, oats, barley, quinoa, rice, etc., are highly susceptible to becoming cross-contaminated with gluten.
People often use the same scooper to handle oats and barley as they do with rice and quinoa.
They’re also careless, dripping remnants everywhere, contaminating the other bins and products.
Read my article, 5 Hidden Sources of Gluten at the Grocery Store, for more sources of cross-contamination at the grocery store.
(8) Oats are Highly Cross-Contaminated
If you’re gluten-free, you know that oats are off-limits unless they’re labeled gluten-free and, even better, certified gluten-free.
Oats are grown in rotation with wheat and other crops, which means they’re grown on shared fields and harvested with shared equipment.
While naturally gluten-free, oats often contain stray gluten grains and gluten dust, making them one of the most gluten-cross-contaminated products around.
There are oats grown on dedicated gluten-free oat fields, known as purity oats, and many companies employ optical and mechanical sorting and cleansing to make regular oats, known as commodity oats, safe for the gluten-free community to consume.
Unless a product containing oats is labeled “gluten-free,” it’s unsafe for people with celiac disease and gluten intolerance to consume. Period.
Learn more about oats in my article, Are Oats Gluten-Free? Unpacking Confusing and Contradictory Information.
(9) Beware of Cross-Contamination at Buffets
At one time, I loved buffets, especially the non-defunct Sweet Tomatoes salad bars and the extravagant buffets in Las Vegas, which I ate at religiously when I visited my grandmother.
Today, I see buffets, hot bars, and salad bars as gluten cross-contamination cesspools!
I’ve watched people use the same tongs to grab various items, leaving the spoon used to scoop the couscous (not gluten-free) inside the mashed potatoes (gluten-free).
My friend once hosted a pasta bar buffet at her home, complete with a big bowl of gluten-free pasta alongside the other pasta dishes.
By the time I got to the pasta bar, I noticed the gluten-free bowl had two spoons in it. One of the spoons from the regular pasta somehow made its way into the gluten-free pasta bowl, which means someone used the spoon from the regular pasta to scoop the gluten-free pasta.
(10) Cross-Contamination Can Occur During Manufacturing
If you’re on a gluten-free diet, one of the most important skills you can master is label reading. I highly recommend enrolling in my SIGNATURE Gluten-Free Course to learn and master this critical skill if you haven’t already.
Cross-contamination can occur during manufacturing when shared equipment is used AND a product isn’t labeled gluten-free.
Keep in mind, however, that products labeled gluten-free and certified gluten-free can be produced on shared equipment. In fact, many gluten-free products are manufactured on shared equipment, as it’s very expensive and difficult to find dedicated gluten-free manufacturing facilities.
These products are 99.9% of the time safe for anyone with celiac disease or gluten intolerance to consume. While there is always a cross-contamination risk, and nothing is foolproof, there’s only a tiny chance it would pose a cross-contamination risk.
Remember, if a product is labeled “gluten-free,” it means the manufacturer has validated that the product meets the FDA’s gluten-free labeling guidelines.
If a product is labeled “certified gluten-free,” it means it has been validated by a manufacturer, following guidelines set forth by a third-party certifying agency, that it’s gluten-free. These guidelines are typically stricter than the FDA’s guidelines.
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 being a victim.
(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.
(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
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.
Read more about Nima in my article, What You Need to Know About Nima Sensor Before You Buy – Perspective from a Celiac & Nutrition Professional, and 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 ordering 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 at a restaurant, even if it’s gluten-free pizza.
Gluten-free pizza is often prepared along the same assembly lines and cooked in the same ovens as regular pizza.
And if you’ve made pizza before, you know flour gets everywhere in a pizza kitchen, and even airborne flour can be harmful to the gluten-free community.
Words of Encouragement
Avoiding all potential sources of gluten Is essential to living a healthy, symptom-free gluten-free life.
Use this information and strategies about gluten cross-contamination to help you make wise decisions about what you will and won’t eat. It’s essential that you protect yourself from accidental gluten exposure at all times.
Learn more tips on how to eat out safely while following a strict, gluten-free diet in my ebook, The Ultimate Guide to Eating Out Gluten Free.
I invite you to enroll in my SIGNATURE Gluten-Free Course to learn more about cross-contamination and the ins and outs of a healthy and fulfilled gluten-free life.
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.
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- How 20 Restaurants Fared When Tested for Hidden Gluten
- Everything You Need to Know about Gluten-Free Labeling Laws and Certifications
- What’s Gluten Free at The Bonefish Grill?
- Survey Reveals ‘Eating Out Safely’ as the Top Challenge Facing the Gluten-Free Community
- Is Wingstop Gluten Free and the Scoop on Chicken Wing Restaurants