Cross contamination of Gluten Free Grains?

This website is dedicated to my gluten-free food experiments, however, sometimes there’s news important enough to ‘migrate’ articles over from my gluten-free dietetics practice.  Here’s my June 2010 GF newsletter.

Are Whole Grains Like Millet, Corn and Rice Safe in a GF diet?

By Cheryl Harris, MPH, RD, LD
A new June 2010 study, “Gluten Contamination of Grains, Seeds, and Flours in the United States” just was published in the American Dietetics Association Journal.  We’ve known for years that oats can be contaminated with gluten, but what about other grains, flours and seeds?

The research team looked at a variety of grains, seeds, flours, etc. NOT marked gluten free and sent them to a lab for testing.  It is important to note that single ingredient foods like rice, millet, corn, etc. are not allowed to simply be labeled “gluten-free” under the proposed FDA ruling.  At best, they can say “all (blank) is gluten-free”.  As this study shows, this may be problematic.

Not surprisingly, the products highest in gluten were flours, such as millet flour, sorghum flour, buckwheat flour and soy flour (soy flours had the highest levels tested).  Amaranth flour had undetectable levels, as did some of the rice flours tested.  Whole grains were a mixed bag.  Some batches of whole grain millet over the recommended FDA proposed ruling of 20 parts per million, but buckwheat, amaranth, rice, etc. were under.

*sigh* As a dietitian who has been recommending for years that people eat “naturally gluten free foods” when possible for the whole grain benefits, this is unfortunate news.  It is important to note this is a small study, and it would helpful to know more about other inherently gluten-free products, like other grains, nuts, seeds, beans, etc. too.  However, especially in light of this study makes a lot of sense to ONLY and ALWAYS purchase flours that are made in a dedicated gluten-free facility and/or ones that are tested for the presence of gluten through the GIG or CSA certification programs, or a place with a dedicated gluten-free facilty.  It also demonstrates large potential loopholes in the proposed FDA gluten-free guidance, because it shows that inherently gluten-free grains may well not be gluten-free in reality.  As the study states, “The FDA may want to modify their proposed rule for labeling of food as gluten-free, removing the requirement that gluten-free manufacturers of inherently gluten-free grains, seeds, and flours must state on product labels that all foods of that type are gluten-free.”

Many thanks to Tricia Thompson, Anne Roland Lee and Thomas Grace for doing this new and important research.


Since I’ve been getting this question a lot, here are a few companies that test
for gluten both in flours and grains:

Bob’s red mill flours and grains
NOTE: not all are GF, but the GF and tested products are well labeled

Eden foods grains

Nu World amaranth: amaranth

Allergy grocer/Ms. Roben’s: contains very detailed
info on how flours are produced and cross contamination

Nearly Normal Flour (Jules Shepherd)

Better Batter Flour:


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Getting the Nutrition You Need with an Eye on the Environment

* Which foods are most important to buy “organic” and why
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June 5th, 10:30-12 at the Kaplan Center for Integrative Medicine in Mc Lean, VA

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About Cheryl Harris

Life played a funny trick on me. I've studied nutrition for years, and much to my surprise, found out that I could manage many of my health issues via diet. I've been GF for years, and I've got a bunch of allergies and sensitivities. But it definitely doesn't keep me from cooking, baking and enjoying my food. Thanks for stopping by.
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6 Responses to Cross contamination of Gluten Free Grains?

  1. Thanks for a great post…I’m just now giving up corn, rice, soy etc…so hard! Have a great day!

  2. Hi Lauren,

    Maybe I misunderstood, but the study doesn’t mean that you have to give rice, soy, etc. It just means that if they’re not from a company that is tested to make sure they are GF, it’s possible that they aren’t.

  3. Kimberly says:

    Wow! Thanks for the article about gluten free grains possibly NOT being gluten free. I thought it was very interesting because I have had SO much trouble with ‘gluten free’ grains! In fact, I have gone grain free. Now I know it was not just all in my head!:)

  4. Thanks for writing about this! I saw a mention about it somewhere else too, and have been trying to process the information. Still not sure if I will change anything in our diet, but it could explain mild symptoms that randomly show up for no apparent reason.

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