Hiatus hernia is a very common problem occurring in up to 60% of the Western population by the age 60, while it is rare in the Third world countries (1). What is a hiatus hernia? The diaphragm is a sheet of muscle that separates the lungs from the abdomen and contains an opening, through which the esophagus (tube) for carrying food to stomach passes. Normally this opening, termed a hiatus fits snugly around the esophagus. When the hiatus weakens and enlarges a portion of the stomach moves up into the chest cavity through the enlarged hiatus. Most often symptoms of the hiatus hernia are heartburn and regurgitation.
            The explanation for the different prevalence of the hiatus hernia in the Western and Third world countries is as follows: the defecation act is a consequence of the voluntary straining with the closed glottis, chain of events known as Valsalva maneuver and accompaniment by the elevation of the intra-abdominal pressure. Repeated and protracted elevation of the intra-abdominal pressure during excessive straining in the sitting defection posture (2, 3) gradually destroys the hiatus tissue finally resulting in a hiatus hernia; the reduced expulsive effort in the squatting defecation posture associated only with a short elevation of the intra-abdominal pressure thus preventing the destruction of the hiatus tissue explaining the low frequency of the hiatus hernia in counties using the squatting toilet.

The common factor for the hemorrhoids and the hiatus hernia is a similar geographical destribution of this problems:hemorrhoids and hiatus hernia are very frequent in Western countries and of low frequency in third World countries. It was confirmed in a direct trial that the changing of the sitting to the squatting defecation posture cure the hemorroids. 
            In distinction from the hemorrhoids the confirmation of the role of the sitting defecation posture in the causation of the hiatus hernia is impossible because of the methodological problems. But as described above the pathophisiology of the hiatus hernia and its  geographical distrubution common with hemorrhoids show that the only possible ethiological factor of the hiatus hernia is unnatural for the human being the sitting defecation posture.
            A practical step was done and designed a new squatting device tailored for the sewage system of the Western world, see the page: Video-film of a new squatting device

1. Burkitt and James, The Lancet, July 21, pp 128-130, 1973
2. Sikirov Isr.J.Med.Sci 25:55-56; 1989
3. Sikirov Digestive Diseases and Sciences 48:1201-1205; 2003

History of hemorrhoid research it is a history of great mistakes.