There are many good things about yeast. Bread rises because of yeast. The fermentation process that lets brewers make beer and wine is caused by yeast. Yeast is made up of tiny organisms that are fungi, like mushrooms. They live in the soil and are an important part of the mix of microorganisms that keep the soil healthy. There are many different kinds of microorganisms in our intestines, and yeasts are one of them. This mix of microbes is called the intestinal microflora, and it is very important to your health. So, yeast can be very helpful when things are just right