The lining of your gut is covered with microscopic organisms, forming an environment called the microbiome. There are over 1000 species of organisms in the microbiome, and maintaining a healthy balance of these organisms is very important for good physical health and can even affect your mood and behavior. Maintaining a healthy balance of microorganisms in your gut happens in two ways: by feeding the micro-organisms in your gut what they like (prebiotics) and by adding good microorganisms to your gut (probiotics).
Prebiotics: Prebiotics include dietary fiber and resistant starches in foods. They are not digested by humans, but act like fertilizer to nourish and promote the growth of good microorganisms in your gut. These specialized plant fibers are found in abundance in fruits, vegetables, and legumes. While food sources are best, there are prebiotic supplements available.
Probiotics: Probiotics contain live organisms that add healthy microorganisms to your microbiome. Fermented foods such as yogurt, sauerkraut, kimchi, and kombucha are good sources of probiotics. There are also a dizzying array of probiotic supplements on the market. Be aware that they contain many different types of microorganisms in varying amounts, but can be useful for people with diarrhea, irritable bowel syndrome, and other intestinal problems.