The human microbiome, which is comprised of all the microorganisms (the microbiota) that live on and in humans, plays an essential role in determining good health. Microbes cover every surface of our bodies, inside and out. They’re on our skin, inside our noses, mouths, whole respiratory tract, plentiful in our digestive tract, reproductive system, and so on. These microscopic life forms consist of thousands of species and outnumber our own 50 trillion cells by about 10 to one.
We are less than 1% human, if you factor in that more than 99% of the DNA contained within us belongs not to us, but to the microbes which we effectively host.
There is some confusion about the difference between pre- and probiotics. There are 400 – 500 types of bacteria in the digestive tract, each of which has many strains, with a total of one hundred trillion bacteria and a weight of about 2 kg (about the size of the liver). Just imagine the chaos created by a course of antibiotics!