The average adult is carrying between 3-5 pounds of microbes or bacteria! This makes your microbiome (or your gut) one of the largest organs in your body. In our entire body the microbial cells outnumber the human cells by up to 10:1. If we measure by DNA cells, each of us has about 20 thousand human genes but we are carrying some 100 trillion microbial genes.... so we are at least 99 -100% microbe!
Scientists are still sniffing out the productive purpose all of these 100 trillion microbes. For example, those on our skin don't necessarily exist for our benefit, but by taking up residence on us, they make it harder for other, nastier microbes to infect us.
We believe the intestines to be the largest and most important microbial community in the body. This is where most of the nutrients from your food are absorbed into the bloodstream. Because microbes work alongside your digestive system, intestinal microbes are the gatekeepers of our metabolism. They have the potential to influence what we eat, how many calories we derive from it, what nutrients and toxins we are exposed to, and how drugs affect us. Eventually, our microbes just slough off and pass right on out with our morning cup of coffee. But the more probiotic rich our diet, the better our body will work.