Probiotics can be beneficial when traveling or stressed by changing the gut environment to indirectly support beneficial microbiota.

“You know, in certain cases they can be, especially if you're traveling or you're stressed, but it turns out that the particular bacteria that they put in most probiotics don't actually replenish the microbiota that you need most... Well, they don't replenish those but they replenish other ones that then in turn encourage the development of the microbiota that you do want once you start eating the appropriate foods.”