Probiotics are living microorganisms regulating the microbial balance of humans.

In the 20th century, it was found that fermented foods have a favorable effect on the microflora in the gut and decrease the microbial activity. The causal factor is that fermented foods are rich in lactobacillus and bifidobacterium, which quite tolerate acidity and thus actively live in the human stomach and gut. Probiotics have various benefits on human health, such as removing toxic substances from the body, fixing intestinal obstruction, and regulating intestines whose natural flora is impaired due to the use of antibiotics. Lastly, kefir, boza, yogurt, and kombucha tea are high in probiotic values.