KEY POINTS:

  • Many grains, flours, and starches are naturally gluten-free including (but not limited to):
    • Corn
    • Rice
    • Sorghum
    • Millet
    • Teff
    • Wild rice
    • Amaranth
    • Buckwheat
    • Quinoa
    • Soy
    • Tapioca
    • Arrowroot
  • Naturally gluten-free grains, flours, and starches may become contaminated with wheat, barley, and rye while being:
    • Grown if wheat, barley, or rye is grown in a field next to a gluten-free grain or if a gluten-free grain is grown in rotation with wheat, barley, or rye.
    • Harvested if the same equipment is also used to harvest wheat, barley, or rye.
    • Transported if the railcar, truck, etc was previously used to transport wheat, barley, or rye.
    • Processed if the same equipment is also used to process wheat, barley, or rye.
    • Stored if gluten-free grain is kept in close proximity to gluten-containing grain.
  • To decrease your chances of eating gluten-free grains and flours contaminated with wheat, barley, or rye it is recommended that you:
    • Buy grains, flours, and starches that are labeled gluten-free.
    • Buy products made with gluten-free grains, flours, and starches that are labeled gluten-free.
  • As you can see from this table, labeled gluten-free flours may contain less gluten contamination than gluten-free flours not labeled gluten- free. 2,3
GLUTEN CONTENT LABELED/UNLABELED GLUTEN-FREE FLOURS:
FLOUR MEAN PPM GLUTEN LABELED GLUTEN FREE MEAN PPM GLUTEN NOT LABELED GLUTEN FREE
Millet 15.5 ppm 305 ppm, 327 ppm
Buckwheat < 5 ppm 65 ppm
Sorghum < 5 ppm 234 ppm
Soy < 5 ppm 92 ppm, 2925 ppm

References: Thompson, Lee, Grace. JADA 2010: 110; 937-940; Gluten Free Watchdog, LLC www.glutenfreewatchdog.org

TAKE HOME MESSAGES:

  • Naturally gluten-free grains, flours, and products made from them may be contaminated with wheat, barley, or rye.
  • Buy labeled gluten-free products whenever possible to decrease your risk of consuming contaminated products.

RESOURCES FOR YOU:

Gluten-Free Dietitian. Contamination of Naturally Gluten-Free Grains. http://www.glutenfreedietitian.com/newsletter/contamination-of-naturally-guten-free-grains/ . Accessed November 3, 2011.

Gluten-Free Dietitian. Contamination of Naturally Gluten-Free Grains: Part 2.http://www.glutenfreedietitian.com/newsletter/contamination-of-naturally-gluten-free-grains-part-2/ . Accessed November 3, 2011.

References:

  1. Celiac Disease Toolkit. American Dietetic Association. Chicago, IL, 2011.
  2. Thompson T, Lee AR, Grace T. Contamination of naturally gluten-free grains, seeds, and flours in the United States: A pilot study. J Am Diet Assoc. 2010;110:937-940.
  3. Gluten Free Watchdog. www.glutenfreewatchdog.org . Accessed November 3, 2011.

Revision Date: 8-29-12 
Author: Tricia Thompson, MS, RD 
Editors: Melinda Dennis, MS, RD, LDN and Daniel Leffler, MD, MS

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