Oat vary among oat varieties. Also, oats products are frequently cross-contaminated with other gluten-containing cereals during grain harvesting, transport, storage or processing. Pure oats contain less than 20 parts per million of gluten from wheat, barley, rye, or any of their hybrids. Use of pure oats in a gluten-free diet offers improved nutritional value from the rich content of oat protein, vitamins, minerals, fiber, and lipids, but remains controversial because a small proportion of people with celiac disease react to pure oats. Some cultivars of pure oat could be a safe part of a gluten-free diet, requiring knowledge of the oat
Wheat gluten (food) 蛋 (tan, from 蛋白 (tanpaku, "protein")). The meaning of the word "seitan" has undergone a gradual evolution. The initial product, imported from Japan in 1969 was a very salty seasoning, the color of soy sauce, sold in a small glass jar or plastic pouch, to be used as a seasoning for brown rice. The name gradually came to refer to any wheat gluten seasoned with soy sauce. The people most responsible for this change are Nik and Joanne Amartseff, who invented Tan Pups in 1972 and John Weissman, who in 1974 invented Wheatmeat (first meatballs then cutlets made of seitan)