A recent article in Everyday Health looks at the use of prebiotics for ulcerative colitis, a bowel disease that causes long-term inflammation and ulcers in the digestive tract. William R. DePaolo, director of the Center for Microbiome Sciences and Therapeutics at the University of Washington School of Medicine in Seattle, was interviewed.

“Think of your gut as a garden,” he said in the item. “If you want to colonize and grow something, you plant seeds. Those seeds would be the probiotics.”

Prebiotics, in contrast, “are the fertilizer you put on that garden,” he explained. They help healthy bacteria grow and thrive and maintain a stable population in your gut.