Probiotics are live microorganisms, mainly lactic acid and non-lactic acid bacteria, as well as yeasts, and exhibit various biological activities. Lactobacillus species, such as Lactobacillus rhamnosus and Lactobacillus acidophilus, Bifidobacterium species, including Bifidobacterium bifidum and Bifidobacterium lactis, as well as Saccharomyces boulardii (a probiotic yeast) are known as common probiotic strains.