We hear a lot about the microbiome these days. But what exactly is it, and how does a healthy microbiome help prevent disease?

“Essentially, we are a walking ecosystem,” says Dr. Sean Spencer, gastroenterologist at Stanford.

“We harbor trillions of microbes on us, but mostly within us. The fascinating thing about the microbiome is that our genome is fixed and has about 40,000 genes. Within the microbiome, there’s about 100 times more genes than human genes.”

Fiber is key to a healthy microbiome. Known as a prebiotic, fiber promotes the growth of beneficial bacteria, which produce microbial metabolites. These metabolites play an essential role in maintaining health, as they influence various bodily functions, including immune response and cognitive processes. They circulate throughout the body – in the bloodstream, tissues, and even reaching the brain. A diet low in fiber starves the microbiome and diminishes its ability to make beneficial metabolites.

According to Dr. Spencer, our microbiome loves fiber.

“Really, the best way to promote microbiome diversity is to eat whole foods because they harbor a diverse array of fibers within them. Whole foods and fermented foods are really going to have everything you need.”

Watch Dr. Spencer’s full Osher Wise presentation on feeding a healthy microbiome to learn more about the role of diet, fiber, and fermented foods in promoting gut health:

Feeding Your Microbiome: Dietary Strategies for Wellness and Disease Prevention