(Image: Oregon Daily Journal, 21 Sept. 1916)
In his natural state, man is not encumbered by social constraints that induce constipation. He, uh, responds to his bodily needs when told by his body. He does not need medicine to regulate his bowels. He might need a natural lubricant to keep them flowing, though. This is the premise behind Nujol, a medicine available in the United States in the 1910s and 1920s.
Nujol is literally made of petroleum. It's a lubricant, like the kind you might put in your car engine. Appropriately, it was a product of the Standard Oil Company. You can read more about it at Weird Universe.