Gluten Contamination of Grains, Seeds, and Flours in the United States: A Pilot Study


      Under the Food Allergen and Consumer Protection Act, the Food and Drug Administration (FDA) must issue a rule for the voluntary labeling of food as gluten-free. In the proposed rule, many single-ingredient foods, such as millet, are considered inherently free of gluten. Inherently gluten-free grains will be considered misbranded if they carry a gluten-free label and do not also state that all foods of the same type are gluten-free (eg, “all millet is gluten free”). Twenty-two inherently gluten-free grains, seeds, and flours not labeled gluten-free were purchased in June 2009 and sent unopened to a company who specializes in gluten analysis. All samples were homogenized and tested in duplicate using the Ridascreen Gliadin sandwich R5 enzyme-linked immunosorbent assay with cocktail extraction. Thirteen of 22 (59%) samples contained less than the limit of quantification of 5 parts per million (ppm) for gluten. Nine of 22 (41%) samples contained more than the limit of quantification, with mean gluten levels ranging from 8.5 to 2,925.0 ppm. Seven of 22 samples (32%) contained mean gluten levels ≥20 ppm and would not be considered gluten-free under the proposed FDA rule for gluten-free labeling. Gluten contamination of inherently gluten-free grains, seeds, and flours not labeled gluten-free is a legitimate concern. 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.
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      T. Thompson is a nutrition consultant on celiac disease, Manchester, MA


      A. R. Lee is director of nutritional services, Schar USA, Santa Fe, NM


      T. Grace is CEO and director of Bia Diagnostics, Burlington, VT