Although you might like to think of yourself as your own person, you actually share your body with many millions of bacteria.
In fact, it's estimated that the human gut contains 100 trillion bacteria, or 10 times as many bacteria as cells in the human body.
These bacteria, or gut flora, influence health in many ways, from helping to extract energy from food to building the body's immune system, to protecting against infection with harmful, disease-causing bacteria.
Researchers are only just beginning to understand how differences in the composition of gut bacteria may influence human health. From what we know so far, here are five ways gut flora affect wellness: