Non-celiac gluten sensitivity yet well understood. It was hypothesized that gluten, as occurs in celiac disease, is the cause of NCGS. Besides gluten, other components in wheat, rye, barley, and their derivatives, including amylasetrypsin inhibitors (ATIs) and FODMAPs, may cause symptoms. Some people may have a reaction to other proteins present in gluten-containing cereals that are able to inhibit amylase and trypsin (-α-amylase/trypsin inhibitors [ATIs]). ATIs are part of the plant's natural defense against insects and may cause toll-like receptor 4 (TLR4)-mediated intestinal inflammation in humans. These TLR4-stimulating activities of ATIs are limited to gluten-containing cereals (wheat, rye, barley, and derivatives) and may
Gluten "generally recognized as safe" (GRAS). In August 2013, the FDA issued a final ruling, effective August 2014, that defined the term "gluten-free" for voluntary use in the labeling of foods as meaning that the amount of gluten contained in the food is below 20 parts per million. Gluten Gluten (from Latin "gluten", "glue") is a composite of storage proteins termed prolamins and glutelins that is stored together with starch in the endosperm (which nourishes the embryonic plant during germination) of various cereal (grass) grains. It is found in wheat, barley, rye, oats and related species and hybrids (such as spelt,