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  • Jefferson Adams
    Jefferson Adams

    The Gluten Contamination Study We've Been Waiting For

    Reviewed and edited by a celiac disease expert.

      Do you really need that dedicated gluten-free toaster and dedicated flatware? A new study says you might not.


    Caption: Image: CC BY-SA 2.0--threefingeredlord

    Celiac.com 10/14/2019 - One of the big debates among people with celiac disease concerns how vigilant celiacs need to be to make sure they avoid gluten. What does science say about gluten contamination in three common scenarios? How careful do you need to be about gluten contamination?

    For example, how likely are you to get gluten over 20ppm if you share a toaster, pasta water, or slice a cupcake with the same knife used to cut a non-gluten-free cupcake?

    A team of researchers recently set out to assess three common scenarios where people with celiac disease might reasonably fear gluten contamination. How did the actual risk for each situation measure up?

    • Scenario 1: Water used to cook regular pasta is reused to cook gluten-free penne and fusilli. The gluten-free pasta is then rinsed and served.
    • Scenario 2: Toasting Gluten-Free Bread in an Uncleaned Shared Toaster Gluten-containing bread is toasted in a toaster. Immediately afterward, gluten-free bread is toasted in the same toaster.
    • Scenario 3: Slicing a Gluten-Free and Regular Cupcake with Same Knife

    The research team included Vanessa M. Weisbrod, BA; Jocelyn A. Silvester, MD PhD; Catherine Raber, MA; Joyana McMahon, MS; Shayna S. Coburn, PhD; and Benny Kerzner, MD. They are variously affiliated with the Celiac Disease Program, Children’s National Health System, Washington, DC, USA; and the Harvard Celiac Disease Program, Boston Children’s Hospital, Boston, MA.

    Their paper titled, Preparation of Gluten-Free Foods Alongside Gluten-Containing Food May Not Always Be as Risky for Celiac Patients as Diet Guides Suggest, appears in Gasterojournal.org.

    Control samples of gluten-free pasta, bread, and cupcakes all tested below the limit of detection. Samples were individually packaged in plastic bags with randomized sample numbers. To avoid “hot spots” and ensure even analysis, all items were homogenized for analysis. 

    Gluten content was measured with R5 sandwich ELISA (R7001, R-Biopharm, Darmstadt, Germany) which has a limit of detection of 5 ppm gluten by Bia Diagnostics (Colchester, Vermont). All control samples were similarly tested. 

    The team then quantified gluten samples as under 5ppm, 5-10ppm, 10-20ppm, or over 20ppm, and based their confidence intervals upon binomial distribution.

    Boiling Gluten-Free Pasta in Regular Pasta Water

    In the first scenario, the team boiled sixteen-ounce packages of gluten-containing Barilla brand penne and fusilli separately in stainless steel pots in fresh tap water for 12 minutes, then removed with strainers. The water was reused to cook Dr. Schar gluten-free penne and fusilli. The team also tested the effect of rinsing some samples of the cooked and contaminated pasta under cold tap water for 30 seconds. 

    The team found that Gluten was detected in all pasta samples cooked in water used for gluten-containing pasta, ranging from 33.9ppm to 115.7ppm. The rinsed gluten-free pasta samples tested at 5.1 ppm and 17.5 ppm detectable gluten. 

    Interestingly, rinsing pots with water alone after cooking gluten-containing pasta was as effective as scrubbing with soap and water to prevent detectable gluten transfer. 

    Toasting Gluten-Free Bread After Non-Gluten-Free Bread

    In the second scenario, the team toasted regular gluten-containing bread in two rolling toasters in a busy hospital cafeteria at 20-minute intervals, or in one of three shared pop-up toasters. Immediately after toasting the gluten-containing bread, they toasted Dr. Schar Artisan White Bread. Gluten-containing crumbs were visible in all toasters. They team did not clean the toasters. 

    The team found that toasting in a shared toaster was not associated with gluten transfer above 20ppm; the four samples with detectable gluten had levels ranging only from 5.1 ppm to 8.3 ppm gluten.

    Slicing a Gluten-Free Cupcake with Knife Used on Gluten Cupcake

    In the third scenario, the team used a knife to slice frosted gluten-containing cupcakes. The knife was then reused to slice a frosted gluten-free Vanilla Cupcake from Whole Foods Gluten-Free Bake House. 

    The knife was then washed in soap and water, rinsed in running water, or cleaned with an antibacterial hand wipe (Wet Ones) and a new gluten-free cupcake was sliced. Both gluten-free cupcakes were analyzed for gluten content.  Although 28/30 cupcake samples had detectable gluten transfer, only 2/28 tested over 20ppm. 

    The team found that cutting cupcakes with a knife used to cut frosted gluten-containing cupcakes was associated with low-level gluten transfer even when crumbs were visible on the icing adhered to the knife. All three knife washing methods tested were effective in removing gluten. 

    The team acknowledges the limitations of their study, including small sample size, etc. They are calling for further study to assess best kitchen practices for people with celiac disease who are trying to avoid gluten contamination in shared kitchens.

    Main Takeaways

    1) Some kitchen activities may pose less of a risk of cross-contact with gluten than is commonly believed. 
    2) Standard washing effectively removes gluten from shared utensils.
    3) Cooking gluten-free pasta in the same water as regular gluten-containing pasta is likely okay, as long as the pasta gets rinsed well.
    4) Sharing a toaster is unlikely to result in gluten contamination.

    Read more in Gastrojournal.org

    Conflict of Interest Declaration: JAS has served on an advisory board of Takeda Pharmaceuticals and received research support from Cour Pharma, Glutenostics, and the Celiac Disease Foundation. The other authors have no conflicts of interest to disclose. Funding Source: Supported by philanthropic gifts from the Celiac Disease Foundation, Dr. SCHAR USA, and Bia Diagnostics. JAS is supported by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health under Award Number K23DK119584. 


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    1 hour ago, Jefferson Adams said:

    Actually, this study used rigorous scientific methodology, and makes its full results public without cost, unlike the site you mentioned. As for the takeaways, many folks have long believed they needed separate eating utensils because they thought that gluten would not rinse off, but this study clearly shows that gluten easily washes off flatware with standard washing methods.  Having a rigorous study actually quantify contamination levels for these scenarios not only not flawed, it helps people actually quantify and understand actual risk levels. More and broader studies of this kind can help people move from fear and worry to actual knowledge and risk management. We welcome more of them.

    The Gluten Free Watchdog relies on subscriptions/donations like the publication Consumer Reports, unlike Celiac.com which relies on advertising dollars from corporations. I think that is significantly different.  Read Tricia  Thompson’s bio to determine her legitimacy.  Her contributions to the celiac community have been great.  

    https://www.glutenfreedietitian.com/about-the-gluten-free-dietitian-tricia-thompson/

    Common sense is that, if washed properly, you can share kitchen utensils that do not contain tiny crevices like a colander.  The study concentrated on boiling pasta in water that gluten pasta had been in previously, using the same toaster that gluten toast had been in and using a knife that had cut food and had not been washed.  In my opinion, those things are not safe for a celiac.  

    This study was released prematurely like so many other medical studies.  I can not judge the scientific methods used as I am not a scientist.   (Your degree was in Fine Arts per your bio).    

    It is estimated that about 60% of celiacs do not heal.  I worry that this study may contribute to increasing that number.  

    https://gluten.org/looking-beyond-gluten-free-choose-gut-supportive-diet-long-term-health-celiac-disease/

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3956033/

    I am thankful that Celiac.com is available for celiacs/NCGS and those wishing to learn about the gluten free diet.    It is without a doubt the number 1 celiac forum (discussion group) in the world.  The emotional support and common sense advice that members share is invaluable.  Thank you, Celiac.com for creating the forum.  

    Edited by cyclinglady

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    1 hour ago, Jefferson Adams said:

    The study provides good methodology and solid scientific method. Not sure where you're getting this "16 washings" stuff, but that's not what the science says. Yes, we do need more studies, and larger ones. And no, I wouldn't recommend sharing a toaster, but I know many celiacs who do not use dedicated utensils, and simply wash them. They are apparently vindicated by this study. As I've said before, knowledge is power.

    This study was meant to help celiacs, but I think in return this may worsen the situation for us celiacs trying to dine out. This study clearly needs to be replicated numerous times  by others to see if they get a similar outcome.  As a celiac for 12 years now, I will never eat gluten-free pasta boiled in the same water as gluten pasta! I don’t care what this ONE study shows. Show me this study done 20+ times by 20+ different scientific groups and then maybe I will believe the results. I appreciate the hard work that was done, but hopefully this one study will not cause carelessness of chefs in preparing gluten-free meals in restaurants. 

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    2 hours ago, Jefferson Adams said:

    Numerous studies demonstrate that the vast majority of people with celiac disease tolerate gluten at 20ppm with no issues whatever.

    And if you're more sensitive than that, you're already in trouble.  I can see this new "study" being used as ammunition by the restaurants that already don't believe it's that important.  Knowledge may be power but assuming it is broadly applicable in all cases is a logical error.

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    Guest Shay as others said. Havin

    Posted

    On 10/19/2019 at 7:24 PM, Awol cast iron stomach said:

    Scary stuff, fitting it's well matched for October -Halloween theme. 🎃

     

    Having become seriously ill for too long periods. I know how important it is for me to be ultra careful. Every illness over the last 25years was cross contamination. As o never eat any gluten 

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    Note that this is about a single cross-contamination scenario. If one were exposed to these sorts of condition for 3 meals a day, 7 days a week... that person would be doubled-over in pain most days of his or her life. 

    ...Which is why I'm currently living in an apartment that is 3x the price I can afford and do not have a roommate: because NO ONE wants to live with someone who requires that these scenarios can never happen. 

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    On 10/21/2019 at 8:41 AM, Karen B. said:

    And for someone that reacts to gluten levels lower than 20 ppm?

    It took me awhile to believe my body was that sensitive but I have proved it to myself over and over. All this"study" accomplished is providing ammo to people to dismiss the concerns and requests of people with Celiac.   

    You are so right!!

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    And it's why I am planning to bring my elderly mom with Celiac to live in my home instead of a senior apartment that might be more fun.  We already found out when she stayed in a rehab facility that the dietitian may say they can do gluten free but the kitchen staff refused to not bury her food in gluten gravy.  God help the person with Celiac that is stuck in an institutional food environment.  This study also won't help that person because it creates the illusion that it's just not that important instead of looking at cumulative effects.

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    On 10/21/2019 at 8:41 AM, Karen B. said:

    And for someone that reacts to gluten levels lower than 20 ppm?

    It took me awhile to believe my body was that sensitive but I have proved it to myself over and over. All this"study" accomplished is providing ammo to people to dismiss the concerns and requests of people with Celiac.   

    I totally agree!!  When I was diagnosed with Celiac, my levels were off-the-chart.  My Dr. said it was the worst case he ever had seen.  I definitely am sensitive to the most minute amount of gluten!  I still am dealing with the ignorance of gluten which I've found at so many restaurants, and I too feel that this study minimizes the need for the necessary caution in food prep.

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    So, do we disregard the information we have been hearing for years, that all it takes is one crumb to get glutened?  This study is hard to fathom although I would love to believe it's true. I won't be taking chances to test out their results.  

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    My husband has celiac and we have seperate pots and pans. I have only 1 pan for regular foods and it's a blue diamond pan. ( DO NOT buy this pan! It's horrible and I hate it!) He accidentally used it one day when I was not home. Within 1 day he had 19 sores in his mouth and was sick for 2-4 weeks. I put everything in the dishwasher and sanitize. He can't even kiss me without getting sick cause of my makeup or if I have eaten gluten. So, I think everyone is different and have it worse than others. We have fixed a lot of the problems and are still working on doing better. It's been 3 years since he was diagnosed. 

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    I don't think this article is very helpful to anyone with celiac. This disease can be so devastating to the body with so many other health issues that are connected to gluten. It's not just diagnosed celiacs that have connected issues anyone I've known who has changed to a gluten free diet has seen great changes in there health. Even heart doctors are telling their patients to go gluten free because of the effect on the arteries and cholesterol levels. Telling people that their body can tolerate any level of gluten is a misconception, and something that has not been proven. If you want to be free of celiac NO gluten in any amount is safe for your body, but until people realize this most will continue to harm themselves in some way or another. I've seen my husband go from near death to a total turn around in his health. But he is not exposed to any amount of gluten because of how we eat in our own home. This is a man who at the age of 42 when diagnosed after years of trying to get answers he finally started to help himself with wonderful results. He has regained his health grown back his bone mass from the osteoporosis and has lots of energy to do whatever he wants. Gluten is a silent killer and most doctors know little about this disease. Read books from the experts who have studied this disease for years. Unless you are getting bloodwork everyday to see what is really happening when you consume gluten you are taking an unnecessary risk by consuming any amount, thats why you are told to go gluten free for this disease to stay dormat in your body. Any amount could be the trigger!

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    4 hours ago, Karen B. said:

    And it's why I am planning to bring my elderly mom with Celiac to live in my home instead of a senior apartment that might be more fun.  We already found out when she stayed in a rehab facility that the dietitian may say they can do gluten free but the kitchen staff refused to not bury her food in gluten gravy.  God help the person with Celiac that is stuck in an institutional food environment.  This study also won't help that person because it creates the illusion that it's just not that important instead of looking at cumulative effects.

    Karen, you are an amazing daughter.  I also have the same concerns.  If I had the expertise, I would open a dedicated retirement home in a warm place like Arizona.  My girlfriend has her Mom live with her (she does not have celiac disease) but she got her mother to join the city’s Senior Center.  Her Mom resisted, but now she insists on going!  She has made many friends.  

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  • About Me

    Jefferson Adams is Celiac.com's senior writer and Digital Content Director. He earned his B.A. and M.F.A. at Arizona State University, and has authored more than 2,000 articles on celiac disease. His coursework includes studies in science, scientific methodology, biology, anatomy, medicine, logic, and advanced research. He previously served as SF Health News Examiner for Examiner.com, and devised health and medical content for Sharecare.com. Jefferson has spoken about celiac disease to the media, including an appearance on the KQED radio show Forum, and is the editor of the book "Cereal Killers" by Scott Adams and Ron Hoggan, Ed.D.

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