According to the definition of prebiotic, the criteria for whether a substance is judged as prebiotic are as follows:
① Not digested or absorbed by the host's gastrointestinal tract, and can reach the large intestine intact;
②It can only be used by one or several kinds of beneficial bacteria resident in the intestinal tract to promote its growth and reproduction or metabolic activity;
③It can improve the composition of intestinal flora. promote host health;
①Induce systemic immunity in the intestinal lumen and improve the host's constitution.
The evaluation of the efficacy of functional oligosaccharides and other prebiotics requires in vitro and in vivo experimental studies. According to the existing research progress, the experimental results of the physiological effects of non-digestible oligosaccharides on the human body can be divided into three levels. as shown in the table below. Two commercial prebiotics, fructooligosaccharides and inulin, have carried out the most detailed in vitro experiments and in vivo evaluations, and have obtained a large number of human trial data.