Introducing the human microbiome


At any one point, there are roughly 40 trillion microbes residing on and within our bodies - from our skin, our mouths, lungs, reproductive organs, to our gastrointestinal tracts (which houses the largest and most complex ecosystem in the body). Most of these microbes consist of bacteria, but there also exist viruses, protozoa, fungi, and archaea.1

While the number of microbes are roughly the same number as human cells in the body, there are about 100 times more microbial genes than there are human genes! And what’s more, these microorganisms have co-evolved with humans over millions of years and, for the most part, are completely harmless to us.

In fact, the gut microbiome (i.e., the ecoystem of microbes and their genes residing in the gastrointestinal tract) carry out several very important functions in the body2, including:

Gut dysiosis (i.e. a disturbance of the gut microbiome) can disrupt these mechanisms and has been linked to various diseases, including inflammatory bowel disease, diabetes, asthma, allergies, and even autism3. We are also beginning to find links between the gut microbiome and mental health! Look out for a future post where we will do a deep dive on the connection between microbes and mood, and how nutrition fits into the puzzle!

Image credit: CDC on Unsplash

Ursell LK, Metcalf JL, Parfrey LW, Knight R. Defining the Human Microbiome. Nutrition Reviews. 2012;70((suppl_1)):S38–44.
Thursby E, Juge N. Introduction to the human gut microbiota. Biochemical Journal. 2017;474(11):1823–36.
Petersen C, Round JL. Defining dysbiosis and its influence on host immunity and disease. Cellular Microbiology. 2014;16(June):1024–33.