Chapter One

Our Silent Partners for Good Health


When I was five years old, I received my first lesson in microbiology from a Dixie cup commercial on TV. It showed magnified images of bug-like microbes, followed by a horrifying picture of a family’s shared, bacteria-laden drinking glass in the bathroom. My health-conscious mother subsequently banished shared glasses and installed Dixie cup dispensers. Thus I learned that all bacteria are bad and that we must avoid them to stay healthy.

Now that I spend my days (and many nights) tracking down the secrets of microbes, I know that none of that is true. In fact, some bacteria—called probiotics—are not only beneficial to our health, but actually essential. The term “probiotics” comes from the Greek: pro, meaning “promoting” and biotic, meaning “life.” Probiotic bacteria normally live in our digestive tract, especially if we eat foods that contain them, such as yogurt with active cultures, aged cheese, and naturally fermented pickles.

As new research is revealing, the probiotic population in our digestive tract often isn’t large enough for optimal health. As a result, other bacteria can proliferate, creating an imbalance. Obviously, this affects how well our digestive system functions. But we’re learning that the impact goes far beyond that. Probiotics are vital for our immune system, too. They actually send signals to the immune system that reduce destructive overreactions, including inflammation. This means that insufficiencies affect immune responses—and therefore every aspect of our health.

Though our bodies don’t always contain enough probiotics...