In case of probiotic bacteria, high diversity does not always equate to better health-promoting effects. Despite the enormous natural diversity of microorganisms that occur in the digestive tract, it is estimated that about four species of bacteria from the genera Bifidobacterium and Lactobacillus dominate in healthy people. We must also remember that the properties of a given bacterium are not dependent on their species but on their strain, which means that Lactobacillus plantarum A and Lactobacillus plantarum B, despite the fact that they are both Lactobacillus plantarum, can have completely different properties. During the formulation of each of our products, the main focus was on the desirable properties of the strains, including high resistance to unfavorable conditions (gastric acid and bile salts), ease of colonization and high anti-pathogen activity. Then, the antagonistic activity of the strains meeting the above expectations was tested. Therefore, such strains were selected that show synergy and do not compete with each other.