Japan returns to a cheap alternative fertiliser made from human waste

In one account from a missionary, he noted that a Korean colleague of his didn't have worms, and he attributed it to the high dosage of garlic in the Korean diet. This guy went on a garlic binge for a month and he said it cleaned out the worms. I'm skeptical of this story, because if the Korean diet prevented worms, the Koreans wouldn't have had worms, but they did and in fact still do in North Korea.