Yogurt has been around for decades, but with the advent of trendy new yogurts like Greek yogurt and skyr, the food has recently returned to the spotlight. It’s touted as a healthy snack that promises everything from a flatter stomach to better digestion. But just how healthy is yogurt, really?

With dozens and dozens of varieties to try — some of which contain as many ingredients — it’s hard to sort out the healthy and the not-so-healthy. Here are four things to keep in mind when choosing your yogurt.