The Blog

The recently released paper, “Preparation of gluten-free foods alongside gluten-containing food may not always be as risky for some celiac patients as diet guides suggest”*(foot note reference below) has led to a lot of discussion in the Boston Children’s Hospital celiac disease team and beyond. We wanted to review and summarize this important research and share our team’s recommendations based on this new information.

The authors tested three scenarios where it was thought that gluten transfer could be high enough to lead to cross-contact, resulting in a gluten-free food having a gluten concentration greater than 20 ppm. This threshold was chosen because food containing less than 20 ppm (less than 0.002 percent gluten) is considered to be “gluten-free” by the U.S. Food and Drug Administration, and products containing less than 20 ppm gluten can be labelled “gluten-free” in the United States, Canada and the European Union. The scenarios tested were:

• Cutting cupcakes with a shared knife: Gluten levels were below 20 ppm in most cases when a knife used to cut frosted gluten-containing cupcakes was then used to cut gluten-free cupcakes. There was no detectable gluten transfer when the knife was washed before cutting the gluten-free cupcakes.
• Cooking pasta: There was significant gluten transfer (up to 115 ppm) when gluten-free pasta was cooked in water used to cook gluten-containing pasta. The amount of gluten was reduced if the gluten-free pasta was rinsed under tap water for 30 seconds. Rinsing the pot with water and then cooking gluten-free pasta in fresh water reduced the gluten content to undetectable.
• Toasting bread: Gluten levels were <20 ppm for all 40 slices of gluten-free bread toasted in the same toaster as gluten-containing bread, even when visible crumbs were present at the bottom of the toaster.

 We have long made recommendations about avoiding cross-contact based on assumptions and expert opinion, with very little actual data. This is the first study to examine common practices when gluten-free food is prepared in the same kitchen as gluten-containing food.  It is valuable to now have more data to help guide assessment of risk of cross-contact and to advise our patients with celiac disease.

Some of the results were anticipated and some were surprises. For example, one of the “hotter” issues brought up by this study is suggested by the title of this newsletter article: toasters.  You likely have a designated GF toaster at home already because classic teaching for decades has recommended having one.  However, this is the first study to investigate gluten cross-contact in toasters, and having a dedicated toaster is probably not as crucial as we previously thought.

Our team’s recommendation is to continue to emphasize/focus on the importance of avoiding gluten and limiting risk whenever possible, but not to the extent that gluten avoidance leads to excessive or unnecessary anxiety or severely limits patient and family activities. This study is a reminder that we need to continue to shift the conversation to think about food choices and activities based on risk.  Understanding which choices are higher risk and which choices are lower risk is important and context-dependent. Following a gluten-free diet is less about following strict rules and more about evaluating risk to make the best choice among the options available at a given meal.

Our take away messages from this study include:

• Products with visible contamination or gluten-containing ingredients should NEVER be eaten.

• If using the same knife with GF and gluten-containing foods, wash the knife before contact with the GF items. Do not use a knife with visible contamination.

• When cooking or preparing foods that are both gluten-containing and gluten-free, try to prepare the gluten-free item first and set aside away from the preparation area of the gluten-containing foods.

• Gluten-free pasta should not be cooked in water that has already been used to cook gluten-containing pasta.

• This study suggested that rinsing GF pasta after it was cooked in shared water may reduce gluten content. However, we do NOT recommend this rinsing-only protocol. Fresh clean water should be used to cook gluten-free pasta.

• It is important to ask at restaurants how they cook and heat up gluten-free pasta to ensure they are not using the same water used to prepare gluten-containing pasta.

• Cooking GF pasta in the same pot you have cooked gluten-containing pasta in is safe - as long as you have washed the pot and use fresh water.
• This helps us answer the frequently asked question, “Do we need separate pots and pans?” The answer is no - as long as you wash items in between use so that there is no visible food residue.

• We do not have data about the use of shared colanders/pasta strainers. At this time, we continue to recommend that you get a separate colander for GF pasta given the difficulties in effectively cleaning colanders and the increased risk of gluten transfer.

• While a dedicated GF toaster is not mandatory, you still need to avoid visible contamination. You may decide that a separate toaster is best for your family. Conversely, you are not neglectful if you choose to use a shared toaster. This may come in handy when you are travelling or when at an occasional sleepover.

As ever, ongoing evaluation of overall risk with your medical team, thinking through the collective risk of the choices you make, is the best treatment for celiac disease.

We are happy to share the latest information and are always here to answer questions and concerns. It is important to follow up with your GI provider and dietitian at least once a year to review your current practices and to learn what has changed over the last year in your life as well as advances in celiac disease research.

* Article Link

The Boston Children’s Hospital Celiac Team:
Janis Arnold, LICSW
Sophie Burge MS, RDN, LD
Alan Leichtner, MD
Tara McCarthy, MS, RDN
Randi Pleskow, MD
Jocelyn Silvester, MD PhD
Dascha C. Weir, MD