WASHINGTON -- The Food and Drug Administration has published a much-anticipated definition of “gluten-free” using a threshold of 20 parts per million, an extremely low amount since studies have shown allergic reactions in humans do not occur until the ingestion of 100ppm or more. As published in the Federal Register, the definition applies to the labeling of food products that do not contain prohibited grains, as well as any ingredients derived from a prohibited grain that hasn‘t been processed to remove gluten. Prohibited grains include barley, numerous varieties of wheat and rye; as well as farina and flour made from any of the proposed prohibited grains. The agency also proposed that foods inherently gluten-free be banned from using labels, unless an on-pack statement declares that all such foods, not just the specific product using the claim, are free of gluten. It‘s estimated that one in every 133 Americans suffers from celiac disease, which can disrupt digestion and cause damage to the small intestine in severe cases. The FDA‘s proposed definition may yet be refined after an additional comment period that ends in April, after which the rule will become permanent.