Imagine yourself in a rainforest. It is hot, it is humid, and you can taste the air. There is green all around you, and so many kinds of trees and plants you cannot count them all. Some have red fruits, and some have tiny purple flowers. And the animals! There are birds, bats, squirrels, and monkeys. Mosquitoes are buzzing in your ear, and a giant Goliath beetle is quietly walking over decaying leaves on the ground. The sheer diversity is overwhelming, and it is almost impossible to describe how all these living things are connected.

The rainforest is an intricate web made of prey, predators, parasites, producers, and consumers. In this complex ecosystem, food and nutrients cycle from one organism to another organism.

Now imagine that same rainforest, but inside of your gut. It is still hot and humid but instead of plants and animals and insects, you have microbes. These are tiny creatures that all look the same under a microscope but are just as different from each other as birds and bats and squirrels and monkeys. It is a diverse, interconnected, and relatively unexplored place. Your gut is one of the most complex ecosystems on the planet.

The microbes in your gut do the same things that other living organisms do: They eat. They reproduce. They give off waste. They are part of a complex ecosystem in which food and nutrients cycle from one organism to another. One microbe’s trash may be another microbe’s treasure.

One key to health for both the rainforest and your microbiome is the diversity of living things that make up the interconnected web. If half of the trees were removed from a rainforest the balance will be upset for the remaining species. Some will die, and others will become overgrown. The same is true for the microbes in your gut.

We have a mutually beneficial relationship with most of our gut bacteria. We provide food, shelter, and a safe habitat. In return, they digest foods for us and produce nutrients we need.

How do we maintain a diverse and healthy microbiome? We feed it the food it thrives on, which is fiber.

Storyline based on a TED talk by Katherine Amato

Use Student Handout The Microbiome: Food, Fiber, and Fitness to answer questions as you progress through each step.