I see. Well yea, 'could' is significantly different than 'can'. The latter implies probiotics have the capacity to be harmful. The former says, 'hey, we don't k

I see. Well yea, 'could' is significantly different than 'can'. The latter implies probiotics have the capacity to be harmful. The former says, 'hey, we don't know – maybe they're harmful?'. "Useless and can actually hurt you" isn't really supported by the evidence. More accurate would be, "probiotics role is still a mystery, requires further study."