This story is from The Pulse, a weekly health and science podcast. Subscribe on Apple Podcasts, Spotify, or wherever you get your podcasts. Find our full episode on poop here. You’ve finally arrived at your destination, and your itinerary is packed with relaxing activities — sleeping in late, lying on the beach, grabbing a piña colada, and feasting on the local food. You’re on vacation; this is what you’re supposed to do.