Probiotics are foods that are made up of good live bacteria or yeasts that naturally stay in the human body. Human body is a host to good and bad bacteria. Whenever one gets an infection, there is more bacteria that is bad. 

Lactose intolerance is a common digestive issue, and research has shown that probiotics may be able to help.

Probiotics may contain a variety of microorganisms. The most common are bacteria that belong to groups called Lactobacillus and Bifidobacterium. Other bacteria may also be used as probiotics, and so may yeasts such as Saccharomyces boulardii.

Gut Microbiota

Gut microbiota are the microorganisms, including bacteria and archaea, that live in the digestive tracts of vertebrates including humans, and of insects. Alternative terms include gut flora and gut microbiome.