In the consumption of dairy products, yogurt has overtaken milk. In recent years, probiotic yogurt has become the main product in yogurt, and the concept of gastrointestinal conditioning and laxative has been accepted by many people. However, does yogurt really have such a great effect? The yogurt with probiotics is usually prominently labeled on the outer packaging with the number of active probiotics in the product, you dare to label 1 billion, I dare to write 2 billion. Not to mention that so many probiotics are seriously counted or calculated, only to say that the probiotics in the yogurt can reach the intestine to play a role? Probiotics are microorganisms that have the ability to break down sugars under anaerobic conditions and have many benefits to the human body. For example, it can adhere to the epithelial cells of the intestinal mucosa, forming a biofilm-like barrier structure and constituting resistance to pathogenic bacteria; it can produce a large number of short-chain fatty acids, lowering the PH value of the local environment and preventing harmful bacteria from adhering to the intestinal epithelium; it promotes intestinal peristalsis and accelerates the discharge of pathogenic bacteria. It also has the ability to secrete a large amount of anti-bacterial substances, or secrete some extracellular enzymes to destroy the mucosal receptors, so that the pathogenic bacteria cannot adhere and invade; it can also activate the phagocytic activity of antibody phagocytes, promote the production of specific and non-specific IgA antibodies, and enhance the function of the immune system. The short-chain fatty acids produced by beneficial bacteria can promote the absorption of calcium and iron; synthesize a variety of vitamins, such as B1, B2, B6, B12, niacin, pantothenic acid, folic acid, etc.; improve the conversion rate of food; digest and decompose anti-nutrients, such as phytic acid, trypsin inhibitor, non-starch polysaccharide, phytoagglutinin, etc., and promote the utilization of nutrients; maintain the stability of the intestinal environment; anti-infective effect, anti-disease such as diarrhea, constipation, digestive tract function, etc.; can combine with aflatoxin B1 to reduce its role in inducing liver cancer, and have inhibitory effects on colorectal cancer, bladder cancer, breast cancer, liver cancer, lung cancer, etc. It is because probiotics have so many benefits, businessmen seize the psychology of consumers, probiotic products came into being. However, probiotics are bacteria in the human intestine that are beneficial to the body, while probiotic products are some microbial products. The former is generated by reproduction in the human intestinal tract, while the latter enters the body through the esophagus. Then, in order for probiotic products to play a regulatory role in the intestinal tract, they must go through the following links, otherwise they can only be considered as a gimmick of the business. First, since probiotics are a kind of microorganism, they will have activity. The so-called activity means that they are constantly multiplying or dying, probiotics are dynamic. So, can these bacteria in yogurt reach the human intestine alive without any problem? How can they pass through the strong acidic gastric juice without being killed? If these bacteria encounter gastric acid, most of them are killed under strong acid, what is left for the killed beneficial bacteria? Second, microorganisms are also composed of proteins, if there are individual beneficial bacteria to avoid the elimination of gastric acid, but the gastrointestinal tract and many digestive enzymes, these digestive enzymes, proteases can break down proteins, these residual bacteria in the role of a variety of proteases can not be overturned? Third, the gastrointestinal tract also has lysozyme, an alkaline enzyme that can hydrolyze mucopolysaccharides in bacteria. It is mainly through the destruction of the cell wall, so that the cell wall insoluble mucopolysaccharide decomposition into soluble glycopeptides, resulting in the contents of the cell wall rupture escape and make the bacteria lysis, which is also a hurdle difficult for microorganisms to pass, I do not know how the probiotics in yogurt break through the bacterial lysis enzyme strangulation? Fourth, if these probiotics are acid-resistant and not afraid of stomach acid, are they also not afraid of alkaline? The human small intestine is an alkaline environment, and the acidic surimi treated by stomach acid will be neutralized by the alkalinity of the intestine and turned into alkaline surimi immediately after entering the intestine. Bacteria that are not afraid of acid, are they not afraid of alkaline? Fifth, even if the probiotic bacteria can break through the acid, alkaline, enzymes and other extermination stubbornly survived, whether it can be planted in the host’s intestine is unknown. Small intestinal peristalsis has a mechanical cleansing effect, which is not conducive to bacterial colonization and reproduction. If the beneficial bacteria can not be colonized in the body, even if the probiotic bacteria can enter the intestine alive will be excreted with the feces, what role can it play in the human body? Sixth, the normal flora in the body has a certain immunogenicity, can stimulate the host to produce the corresponding antibodies, this antibody does not produce antigen antibody response to itself. However, there may be inhibitory effects on other genera of bacteria, which is closely related to the mechanism of maintaining the balance of intestinal flora. That is, the bacteria that enter through the esophagus will cause the body’s antigenic antibody response and destroy them, can the probiotics in yogurt escape? It seems that to regulate the balance of intestinal flora, it is better to supplement dietary fiber, because, after dietary fiber reaches the intestine, it can proliferate beneficial bacteria through enzymatic digestion, which is the main source of beneficial intestinal bacteria.