Barley and their hybrids and derivatives, barley contains gluten, which makes it an unsuitable grain for consumption by people with gluten-related disorders, such as celiac disease, non-celiac gluten sensitivity and wheat allergy sufferers, among others. Nevertheless, some wheat allergy patients can tolerate barley or rye. Barley is a key ingredient in beer and whisky production. Two-row barley is traditionally used in German and English beers. Six-row barley was traditionally used in US beers, but both varieties are in common usage now. Distilled from green beer, whiskey has been made primarily from barley in Ireland and Scotland, while other countries have used
Gluten-free diet Manufacturing Practices and allergen control measures adopted are not sufficient to prevent the presence of accidental trace amounts. When a product contains the warning of cross-contamination with wheat, rye, barley, oats and their hybridised strains, the warning "contains gluten" is mandatory. The law does not establish a gluten threshold for the declaration of its absence. Health Canada considers that foods containing levels of gluten not exceeding 20 ppm as a result of contamination, meet the health and safety intent of section B.24.018 of the Food and Drug Regulations when a gluten-free claim is made. Any intentionally added gluten, even at