Barrett's Esophagus

The esophagus is typically characterized as having a stratified squamous epithelium that protects against mechanical damage that can be induced by the peristaltic action of the esophagus on food. In patients who have chronic gastro-esophageal reflux disease (GERD), the lower portion of the esophagus is exposed to large amounts of stomach acid and undergoes a metaplastic change. This metaplastic response involves the development of a columnar, secretory epithelium typical of the duodenum and small intestine. While this new mucous-producing epithelium is protective, the metaplasia may serve as a precursor to esophageal cancer. Why might this type of metaplasia be protective to the esophagus?