Epidemiology
Incidence of hiatal hernias increases with age; approximately 60% of individuals aged 50 or older have a hiatal hernia. Of these, 9% are symptomatic, depending on the competence of the lower esophageal sphincter (LES). 95% of these are "sliding" hiatus hernias, in which the LES protrudes above the diaphragm along with the stomach, and only 5% are the "rolling" type (paraesophageal), in which the LES remains stationary but the stomach protrudes above the diaphragm. People of all ages can get this condition, but it is more common in older people.
According to Dr. Denis Burkitt, "Hiatus hernia has its maximum prevalence in economically developed communities in North America and Western Europe ... In contrast the disease is rare in situations typified by rural African communities." Burkitt attributes the disease to insufficient dietary fiber and the use of the unnatural sitting position for defecation. Both factors create the need for straining at stool, increasing intraabdominal pressure and pushing the stomach through the esophageal hiatus in the diaphragm.
Read more about this topic: Hiatus Hernia