According to the World Gastroenterology Organization, probiotics are live microorganisms that, when ingested in the right quantities, can provide health benefits for those who consume them. These are bacteria or yeasts that are present in foods, medications or dietary supplements. 

The most commonly used probiotics are those belonging to the species Lactobacillus and Bifidobacterium, the former being the ones that have been used the most for years for the preservation of food through fermentation, as is the case of milk when fermented to produce yogurt. . However, from the scientific and strict point of view, the term probiotic should be reserved for those living microorganisms that have shown their health benefit in studies carried out with people. 

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Prebiotics are compounds that the body can not digest, but that have a physiological effect on the intestine by selectively stimulating the growth and activity of beneficial bacteria (bifidobacteria and lactobacilli). It is a type of carbohydrates (a "special fiber") present in some foods that, although our digestive system is not able to digest, are fermented in the gastrointestinal tract and used as "food" by certain intestinal bacteria beneficial The most studied prebiotics are two: inulin and fructooligosaccharides (also known as FOS), and may appear naturally in some foods or be added by the manufacturer to provide the food with specific benefits.

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