This explanation is indirectly supported by a study of Hollon et al. (2013) showing that persistence of gastrointestinal symptoms in celiac patients on a GFD is abolished, in 85% of cases, by the adoption of a diet based exclusively on naturally gluten-free products, and on the elimination from the diet of commercially available processed food and products labeled "gluten free " (Gluten Contamination Elimination Diet, GCED).