I'd like to note that when I've made natto, which process took me a couple of years to master, due to various stages of laziness when using protocols, I've felt wiggling in my intestines which I think are roundworms and flukes dying. The bacteria which ferments natto produces proteins similar to insecticidal chemicals and many at least one species of roundworm and possibly one kind of fish fluke are known to be succeptible to it.