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Researchers Suggest Proposed FDA GF Labeling Guidelines in Need of Revision

32% of naturally GF grains/seeds/flours tested had excessive levels of gluten


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Researchers Tricia Thompson, MS, RD, Anne Roland Lee, MSEd, RD, LD and Thomas Grace recently published findings of a study designed to assess potential gluten contamination in single-ingredient grains, seeds and flours considered “inherently” gluten-free but not labeled as "gluten-free." The study appears in the June 2010 issue of Journal of the American Dietetic Association.

At the heart of the new study is concern that the current proposed FDA voluntary gluten-free labeling guidelines for manufacturers may be inappropriate and in need of revision based on the findings of this study.

The current proposed FDA gluten-free voluntary labeling guidelines would require that manufacturers that choose to label inherently gluten-free products "gluten-free," state on the label that “all (foods of this type) are gluten-free.”

For example, a manufacturer that does not test their products for gluten but chooses to label their sorghum flour “gluten-free” - under the current FDA labeling proposal, must state on the label that “All sorghum is gluten-free.” But is it?

The study authors voice their concern for the current FDA gluten-free labeling proposal because they found that 32% of the 22 single-ingredient grain, seed and flour products tested, products considered to be “inherently” gluten-free, actually contained gluten levels ≥20 ppm. Their analytical findings suggest that “oats might not be the only inherently gluten-free grain potentially contaminated with gluten” and that “any inherently gluten-free grain, seed and flour can become contaminated with wheat, barley and/or rye while being harvested, transported and/or processed.”

Grain, seed and flour products were tested for gluten with the "R5 ELISA" test, used by the Codex Committee which regulates labeling of gluten-free products in the European Union. Codex allows products to carry a “gluten-free” label when they are tested and found to contain ≤20 ppm gluten. Following Codex guidelines, the FDA has proposed accepting the same 20ppm level of gluten in foods labeled gluten-free in the US.

Grains, seeds and flours analyzed for gluten content in the study. Which ones contained levels of gluten over 20 ppm?

  • millet flour - yes
  • millet grain - yes
  • white rice flour - no
  • rice flour - no
  • Basmati rice - no
  • long grain brown rice - no
  • buckwheat flour - yes
  • hulled buckwheat - no
  • buckwheat groats - no
  • sorghum flour - yes
  • soy flour - yes
  • amaranth flour - no
  • amaranth seed - no
  • flax seed - no
  • enriched corn meal - no
  • instant polenta - no

Single ingredient products tested were not labeled "gluten-free." Twenty-two samples from various manufacturers were purchased and tested. No quinoa or teff products were tested.

Three of the "inherently" gluten-free products tested - soy flour, millet flour and sorghum flour contained levels of gluten in excess of 20ppm. One soy flour product was found to contain mean ppm gluten at 2,925 ppm, one millet flour product contained 327 ppm gluten and one sorghum flour product contained 234 ppm gluten.

Update: 1/2012

Thomas Bjorkman at Cornell University, Department of Horticulture has commented on the results of this study, importantly noting that of the samples evaluated, all whole grain products (except one of the whole millet samples) tested at less than 5 parts per million (ppm) gluten, a level considered safe for "gluten-free" labeling.

In comparison, the milled flours, with the exceptions of rice flour and amaranth flour were found to have varying levels of gluten contamination above 20 ppm. This finding indicates that milled gluten-free flours are at increased risk for cross contamination with gluten in the refinement process.

Researchers concluded that a larger study is needed to identify which grains, seeds and flours are most at risk for cross-contamination with gluten. They also suggest that in light of their findings, the FDA needs to rethink their current labeling proposal of products that are considered “inherently” gluten-free but are not tested for gluten levels.

While brands tested were not divulged in the study results, 59% of the products tested were found to contain ≤5 ppm gluten and 32% contained ≥20ppm, the level at which manufacturers would not be allowed to label their product “gluten-free” under current FDA proposed guidelines.

The results of this study indicate that cross-contamination of gluten-free milled flours may be more widespread than we realize.

Without FDA gluten-free labeling guidelines in place, the gluten-free consumer is at continued risk of unknowingly being exposed to gluten contamination, potentially at excessively unsafe levels.

What can we do? Look for gluten-free products that are tested for gluten and carry the "Certified Gluten-Free" label.


Journal of the American Dietetic Association, June 2010, "Gluten Contamination of Grains, Seeds and Flours in the United States: A Pilot Study" by Tricia Thompson, MS, RD; Anne Roland Lee, MSEd, RD, LD and Thomas Grace, pp 937-940

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