There are a lot of buzzwords around gut health, and the various players in the microbial universe. Here are a few basic terms to educate yourself:
Meet the ‘Biotics family!
Foods containing substances (mostly fibers) that we cannot digest, but which feed our good microbes.
Live bacteria that confer a health benefit when ingested. Found in raw fermented foods like sauerkraut, kimchi, yogurt, kombucha, miso, certain cheeses, pickles, kefir and probiotic pills. Learn more about the history of probiotics.
A combination of synergistic prebiotics and probiotics; usually in a supplement form
Live microorganisms that confer health benefits to people with psychiatric illnesses such as anxiety and depression. (A subset of probiotics.) Major genera include Lactobacillus and Bifidobacteria.
Here’s a great book on the subject.
The metabolic byproducts of probiotic bacteria such as acetate, butyrate, and propionate. these are short chain fatty acids which are used as energy by the host (us!)
Note that even in a healthy gut, pathogenic organisms (bacteria, fungi, viruses) exist; they are kept in check by the “good” guys.