What is the Human Microbiome?

Video Courtney of CSIRO.

The human microbiome is the diverse community of microorganisms – bacteria, viruses, and fungi – that inhabit every surface of our bodies: our skin, our mouths, our noses and our gastrointestinal tract (gut). Micro comes from the Greek (mikrós) meaning (extremely) small. Biome refers to the plant and animal community within a particular habitat; the same concept is often referred to as an ecosystem.

The microorganisms that live in harmony with our own cells, cooperating with our immune system to ward off infection and helping our gut to break down nutrients, are called commensal microorganisms or good bacteria. Those that infect or cause illness are called pathogenic microorganisms or bad bacteria. At any given time, our bodies contain a complex balance of commensal and pathogenic microorganisms. This melting pot of microorganisms outnumbers our own cells ten to one!

Gut microbiome: The community of microorganisms that lives in an individual’s gastrointestinal tract.

Each segment of the human microbiome can be affected by how we treat our bodies. Lotions, creams and soaps can change the microbiome of our skin; toothpaste and mouthwash can change the microorganisms in our mouths; and what we eat can change the microbiome in our gut. Because commensal bacteria play such important roles in our immune system and in nutrient absorption, maintaining the correct communities of “good” bacteria is necessary for optimal health. Factors such as poor diets, medications and diseases can upset this delicate ecosystem. Factors such as fiber-rich diets, exercise and probiotics can strengthen the communities of “good” bacteria and push the gut ecosystem in the right direction.