Updated: Jan 2
If you are one of the millions of people who have celiac disease (three million in the US alone) then you know how difficult it can be to maintain a gluten-free diet, especially when eating out or if you share a home with someone who eats foods that contain gluten. Even a tiny crumb of bread or other gluten-containing food particle that gets accidentally mixed with a gluten free food becomes a danger to a person who has celiac disease. As a chef who received training in culinary school, and having both family and close friends with celiac disease, I offer more than just casual or superficial knowledge on this subject.
Safely navigating your daily nutritional adventures is a challenge, but if you are knowledgeable about possible sources of gluten and the causes of cross-contact then you can significantly reduce the risk of accidentally ingesting gluten. We at Soulstice Nutrition offer the following suggestions and identify common, but often overlooked, sources of gluten cross-contact. Read on to better understand some of these sources and to find ideas on what you can do to prevent gluten cross-contact.
First things first…
What is celiac disease?
Celiac disease is a digestive disorder that damages the small intestine. It affects approximately 1% of the population. The disease is triggered by eating foods containing gluten. Gluten is a protein found naturally in wheat, barley, and rye, and is common in foods such as bread, pasta, cookies, and cakes. Many pre-packaged foods, lip balms and lipsticks, toothpastes, vitamin and nutrient supplements, and, rarely, medicines, contain gluten.
Celiac disease can cause long-lasting digestive problems including, but not limited to, inflammation and intestinal damage, GI symptoms such as diarrhea, nutritional abnormalities, and systemic complications ranging from anemia and osteoporosis to secondary autoimmunity.
Gluten sensitivity affects approximately 18 million people in the US, or ~6% of the population. Gluten sensitivity is different from celiac disease in that if you have gluten sensitivity, you may have symptoms similar to those of celiac disease such as abdominal pain, diarrhea, and fatigue. Unlike celiac disease, gluten sensitivity does not damage the small intestine.
What is cross-contact?
Cross-contact is what happens when a gluten-free food or ingredient comes into contact with a gluten-containing food. The result is the gluten-free food now contains a small amount of the gluten it was exposed to, thus making it unsafe for people with celiac disease to consume. There are a great number of sources of cross-contact at home, in restaurants, and even where the ingredients themselves were grown, processed, or manufactured. Some of these sources are obvious, some less-than-obvious and others are hidden in surprising places.
It might seem overwhelming to remember all the possible sources of cross-contact, but that proactiveness and diligence will be worth it when you find yourself with improved health and a higher quality of life.
What are some hidden sources of gluten in the home?
Gluten can hide in lots of places in your home. It can be extremely difficult to maintain a completely gluten-free household. Budget constraints, cabinet space, and who you share your home with can all influence your decisions and the challenges you face. Take a look at the following infographic, provided by beyondceliac.org, that highlights many gluten hot spots around your home.
Now we will focus on potential sources of gluten cross-contact in shared kitchens.
Are the sponges and dish towels which have cleaned cookware used to make gluten-containing foods safe to use on my dedicated gluten-free cookware?
No. You should keep sponges and dish towels used to clean gluten-free cookware separate from the items used for gluten-containing cookware.
Explanation: Gluten is not a bacteria or pathogen that can be “sanitized” away with bleach or high heat. Any gluten-containing crumbs that might cling to a dish towel or hide in a sponge has the opportunity of being transferred to gluten-free plates or utensils. Also, you must make sure to use fresh dish water if you are hand-washing your dishes since gluten particles can be transferred onto otherwise clean dishes during rinsing. Wash the dishes that were used for gluten-containing foods last, after you wash the dishes that held gluten-free food.
Can I use food products from the same containers used to prepare gluten-containing foods?
No, absolutely not!
Explanation: Knives or other utensils that are used to spread butter, jelly, mayonnaise, peanut butter, and many other food products onto gluten-containing breads, crackers, and bagels will undoubtedly have transferred gluten back into that food item, even if it was bought as a certified gluten-free item from the market.
The safest practice is to have separate and clearly labeled food products and condiments that are dedicated as gluten-free. Households might find it helpful to discuss gluten-free rules and best practices and the importance of being honest about mistakes. If someone accidentally uses a knife that has gluten on it and dips it into the gluten-free peanut butter, it is that person’s responsibility to make sure their housemates are aware that the peanut butter is no longer safe for the person with celiac disease.
Are cutting boards and counter-tops sources of gluten cross-contact?
Explanation: Chef knives used on cutting boards made out of wood or artificial materials can cause cuts on the surface of the board. These can be almost invisible to the eye but can still trap gluten within the tiny valley created by the knife cut and then be transferred to a gluten-free food. It is recommended to purchase and use cutting boards only for use with gluten-free food preparation. Cutting boards come in many different colors which can help differentiate which cutting boards are gluten-free and which are for gluten-containing foods.
Is airborne flour a possibility and should I be concerned?
Explanation: Flour can stay airborne for 12-24 hours after it is used, depending on factors such as ventilation and the size of your kitchen. These airborne particles can pose a danger if accidentally inhaled and/or ingested. Typically gluten cannot be absorbed through the skin, so merely touching flour will not cause issue, but it is safest to avoid areas with possible airborne flour for 24 hours after it was used for food preparation. Baking especially has a high occurrence of creating airborne flour due to the technique of “flouring the board” which is essentially scattering small handfuls of flour across a counter or cutting board using a sideways tossing motion. Think of a farmer tossing feed to chickens or a poker player dealing a hand of cards, except with clouds of flour!
Can I use the same oil for frying gluten-free food items that was used to fry gluten-containing foods?
No, fresh clean oil and a clean pan or dedicated fryer must be used.
Explanation: High heat does not “kill” the gluten proteins. These gluten-containing particles will transfer onto gluten-free food during the frying process and make that food a danger to those with celiac disease. The only way to avoid cross-contact is to use a different pan with fresh oil, or a completely different fryer with dedicated gluten-free oil.
Can I use the same water to boil gluten-free pasta that was used to prepare gluten-containing food?
No, fresh water must be used.
Explanation: Similar to the fry/oil scenario above, gluten cannot be “killed off” with boiling water and as such, the water used to boil gluten-containing foods remains dangerous to people with celiac disease. Fresh water in a completely clean pot must be used to prepare gluten-free foods. Also, gluten-free pasta must be drained in a clean and (preferably) dedicated gluten-free colander.
Is it safe to cook gluten-free foods on the same grill that was used to cook gluten-containing foods?
No. This fact is of particular importance when eating out at a restaurant.
Explanation: Gluten-containing sauces and marinades or even crumbs from toasting buns can adhere to the surface of the grill grate (or flat-top griddles commonly used in restaurant kitchens) which can then be transferred onto gluten-free foods. Once those foods have been charred on, it can become extremely difficult to remove 100%. You might consider purchasing a small grill dedicated for cooking your gluten-free foods.
In a restaurant setting, it is common practice to cook naturally gluten-free foods on the same surface, or fried in the same fryer, as gluten-containing foods. Un-marinated meats such as steak or fish, vegetables, eggs, etc. that would have previously assumed to be gluten-free are no longer a safe bet for a person with celiac disease to order from the menu without specific instructions. Their gluten-free preferences must be communicated to their server or a manager to ensure the kitchen staff understands the importance of using gluten-free dedicated equipment and cooking methods to prevent cross-contact. Every restaurant kitchen I’ve ever worked in has always been diligent and happy to oblige any request made regarding gluten-free or other food allergy. Even if the menu item is labeled as gluten-free, please inform the restaurant staff of your situation to minimize the risk of cross-contact.
Speaking of restaurants, is it safe to eat at a buffet that has both gluten-free and gluten-containing foods?
Sometimes, but only conditionally.
Explanation: Gluten-free offerings on a buffet only remain gluten-free until a person accidentally uses the wrong tongs or places a spoon that came into contact with a gluten-containing food onto the wrong tray. No matter how diligent the people were in the preparation of gluten-free items, there is no guarantee those foods will never be exposed to cross-contact once they are presented to the public. There is always the option of speaking to the chef directly to see if they can bring out a freshly prepared plate of gluten-free foods from the kitchen. Another solution would be to work with the chef or caterer to arrange the opportunity to serve yourself first before possible cross-contact might happen.
Where is the best place for storing my gluten-free foods in the refrigerator or pantry?
On the top shelf or above gluten-containing foods.
Explanation: Gravity. If you store gluten-containing foods above gluten-free foods, then you run the risk of a crumb or other gluten-containing particle falling onto your gluten-free items. Food safety experts utilize a level system for storing different categories of food, those with the most potential for causing food-borne illnesses goes on the bottom and ready-to-eat foods on the top. Raw chicken on the bottom, followed by pork, beef, fish, vegetables, and finally prepared food on the top shelf. The same method will serve you at your home with the very top being reserved for your gluten-free food items or have them in a dedicated area of your pantry. It is also important to label your gluten-free foods clearly, possibly using color-coded tape or stickers to help your housemates easily identify those foods.
I hope we at Soulstice Nutrition have provided a good starting point for identifying potential sources for gluten cross-contact at home shared by those with celiac disease or gluten sensitivity and those without. It can seem daunting when you first receive a diagnosis of celiac disease. Knowing your eating habits must change, looking around your kitchen and home, wondering where to start this new adventure, and being concerned that gluten lurks behind every corner. You can see from the tips and suggestions above that being proactive, staying aware, and arming yourself with knowledge goes a long way to minimizing risk as you travel along your gluten-free journey.
National Institute of Diabetes and Digestive and Kidney Diseases. (2019) Definition & facts for celiac disease. Retrieved from https://www.niddk.nih.gov/health-information/digestive-diseases/celiac-disease/definition-facts
Nadhem, O. N., Azeez, G., Smalligan, R. D., & Urban, S. (May 04, 2015). Review and practice guidelines for celiac disease in 2014. Postgraduate Medicine, 127, 3, 259-265.
Pietzak, M. Celiac Disease, Wheat Allergy, and Gluten Sensitivity: When Gluten Free Is Not a Fad.
Journal of Parenteral and Enteral Nutrition. 2012;36:68S-75S.Bottom of Form
Beyond Celiac. (2019) Cross contact. Retrieved from https://www.beyondceliac.org/gluten-free-diet/cross-contact/