My colleagues (Anne Lee, Schar, USA and Thomas Grace, Bia Diagnostics) and I recently published findings from a pilot study on grain contamination in the June issue of the Journal of the American Dietetic Association (Thompson T, Lee AR, Grace T.
Gluten Contamination of Grains, Seeds, and Flours in the United States: A Pilot Study. J Am Diet Assoc. 2010;110:937-940). What follows is a summary of study findings.
Bottom line: Seven of 22 (32%) samples tested contained mean gluten levels above 20 ppm with amounts ranging from 25 to 2,925 ppm.
Why we conducted this study: In the FDA’s proposed rule for labeling of food as gluten free, single ingredient foods, such as corn, rice, and millet are considered inherently gluten free. These grains will be considered misbranded if they carry a gluten-free label that does not also state that all foods of that same type are gluten free (e.g. “all millet is gluten free” or “millet, a gluten-free food”).
Oats are the only grain that will not 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. In fact, because research suggests that commercially available oats may be contaminated with wheat, barley, and rye, labeled gluten-free oats will be considered misbranded if the label implies that all oats are gluten free.
Unfortunately, oats may not be the only naturally gluten-free grain contaminated with gluten.
What we tested: Twenty-two naturally gluten-free grains, seeds, and flours NOT labeled gluten-free were tested in duplicate using the Ridascreen Gliadin sandwich R5 ELISA with cocktail extraction. Seven of the 22 products contained a voluntary allergen advisory statement for wheat; 15 did not. Products included white rice and flour, brown rice, corn meal, polenta, buckwheat and buckwheat flour, amaranth seed and flour, flax seed, millet grain and flour, sorghum flour, and soy flour.
Findings: Thirteen of 22 (59%) products contained below the limit of quantification for gluten which is 5 ppm for the assay used. Of these 13 products, 3 contained a voluntary allergen advisory statement for wheat. Nine of 22 (41%) products contained more than the limit of quantification for gluten, with mean gluten levels ranging from 8.5 to 2,925. Of these ...
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