Primary constipation: an underlying mechanism.

Primary (simple) constipation is a consequence of habitual bowel elimination on common toilet seats. A considerable proportion of the population with normal bowel movement frequency has difficulty emptying their bowels, the principal cause of which is the obstructive nature of the recto-anal angle and its association with the sitting posture normally used in defecation. The only natural defecation posture for a human being is squatting. The alignment of the recto-anal angle associated with squatting permits smooth bowel elimination. This prevents excessive straining with the potential for resultant damage to the recto-anal region and, possibly, to the colon and other organs. There is no evidence that habitual bowel elimination at a given time each day contributes considerably to the final act of rectal emptying. The natural behavior to empty the bowels in response to a strong defecation reflex alleviates bowel emptying by means of the recto anal inhibitory reflex.