IMAGINE THAT FROM
the time you’re born, your body is hosting a daily house party. Who’s on the guest list? Roughly 40 trillion of your tiniest, closest friends. And like any lively party, there’s a mix of good and bad guests. This community of microorganisms, which includes bacteria, viruses, fungi and yeast, is collectively known as microbiota, or our microbiome. It’s often called the “forgotten organ” and could be considered one of our largest in terms of cells. In fact, recent research suggests that we have around the same number of bacterial cells as human cells. During a natural birth, you’re rst exposed to bacteria from your mother, and it’s estimated that your ecosystem is largely established by age three. We’re used to thinking of bugs as unwanted party crashers, but researchers are discovering that they play an important role in our overall well-being and may hold the key to a host of healthrelated issues.