A gluten-free diet (GFD) is a diet that strictly excludes gluten, a mixture of proteins found in wheat and related grains, including barley, rye, oat, and all their species and hybrids (such as spelt, kamut, and triticale). The inclusion of oats in a gluten-free diet remains controversial.Oat toxicity in people with gluten-related disorders depends on the oat cultivar consumed because the immunoreactivities of toxic prolamins are different among oat varieties. Furthermore, oats are frequently cross-contaminated with other gluten-containing cereals. The long-term effects of consumption of uncontaminated oats (labelled as "pure oat" or "gluten-free oat") are still unclear and further studies identifying the cultivars used are needed before making final recommendations.
Gluten causes health problems for those with gluten-related disorders, including celiac disease (CD), non-celiac gluten sensitivity (NCGS), gluten ataxia, dermatitis herpetiformis (DH) and wheat allergy. In these people, the gluten-free diet is demonstrated as an effective treatment, but several studies show that about 79% of the people with coeliac disease have an incomplete recovery of the small bowel, despite a strict gluten-free diet. This is mainly caused by inadvertent ingestion of gluten. People with poor basic education and understanding of gluten-free diet often believe that they are strictly following the diet, but are making regular errors.