I've read accounts from Americans living in post-WW2 Japan. Intestinal worms were nearly universal due to the use of human waste as fertilizer. In one account

I've read accounts from Americans living in post-WW2 Japan. Intestinal worms were nearly universal due to the use of human waste as fertilizer. 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.