What Are Probiotics?
Probiotics are live microorganisms that are intended to have health benefits. Products sold as probiotics include foods (such as yogurt), dietary supplements, and products that aren’t used orally, such as skin creams.
Although people often think of bacteria and other microorganisms as harmful “germs,” many microorganisms help our bodies function properly. For example, bacteria that are normally present in our intestines help digest food, destroy disease-causing microorganisms, and produce vitamins. Large numbers of microorganisms live on and in our bodies. Many of the microorganisms in probiotic products are the same as or similar to microorganisms that naturally live in our bodies.
Source: http://nccih.nih.gov/health/probiotics/introduction.htm
