Comment Re:If we evolved to have them... (Score 1) 260
Well, one of the theories regarding Crohn's disease and UC (both auto-immune bowel diseases) is that those people are missing a parasite. The disease apparently exist mostly/only in countries with high hygienic standards maybe also combined with certain dietary habits.
They are therefor experimenting with reintroducing certain parasites (and not just bacteria) in the human gut to counter the disease since pumping someone full with hormones or turning someones immune system off has its side effects.
So if you want side effects of not enough bacteria, this could be one.