"You don't necessarily need probiotics — a type of 'good' bacteria — to be healthy. However, these microorganisms may help with digestion and offer protection from harmful bacteria, just as the existing 'good' bacteria in your body already do.
Prebiotics are nondigestible carbohydrates that act as food for probiotics. When probiotics and prebiotics are combined, they form a synbiotic. Fermented dairy products, such as yogurt and kefir, are considered synbiotic because they contain live bacteria and the fuel they need to thrive."
First and foremost, probiotic foods are excellent for maintaining healthy gut flora. You already know how important your gut flora are for just about everything: if you want healthy digestion, clear skin, metabolic health, a generally good mood, easier weight loss, or pretty much anything else, pampering your gut flora should be at the top of your priorities list.
The 'good bugs' in probiotic foods are some of the very same bacteria that populate a healthy gut, so when you eat these foods, it’s an infusion of healthy flora right where they need to be."