The human intestine is a huge reservoir of bacteria. The number of normal flora that maintain health is several tens of trillion to several trillion, weighing more than 1.5 to 2 kg. Ninety-five percent of the body’s flora is in the digestive tract, and its number is closely related to the availability of an aerobic environment and the pH of the digestive tract, i.e., the pH value. Bifidobacterium bifidum decomposes and metabolizes soluble dietary fiber to produce short-chain fatty acids such as acetic acid, butyric acid, lactic acid, propionic acid, etc., which reduces the acidity (pH) of the intestinal tract and facilitates the absorption of iron, calcium, zinc and phosphorus, which is very beneficial to the prevention of anemia, rickets and zinc deficiency. Therefore, restoring and increasing the number of bifidobacteria and their predominance and re-establishing the intestinal micro-ecological balance are important measures for the prevention and successful treatment of viral, bacterial, fungal and even antibiotic-related diarrhea. Bifidobacteria in the infant intestine prevent the invasion of pathogenic, conditionally pathogenic bacteria by binding to phosphatases in the epithelial cells of the intestinal mucosa and together with other anaerobic bacteria they occupy the surface of the intestinal mucosa, forming a biological barrier. The phosphatase secreted by Bifidobacterium bifidum can degrade the α-casein in breast milk, thus facilitating the absorption of milk protein. The β-galactosidase secreted by Bifidobacterium bifidum can accelerate and prolong the decomposition of lactose, which is good for improving the digestibility of lactose and relieving lactose intolerance in some infants and children. Bifidobacteria can synthesize many vitamins in the human intestine, such as vitamin B1, vitamin B2, vitamin B6, nicotinic acid, pantothenic acid, folic acid, vitamin B12, vitamin K and biotin. Once these vitamins are synthesized, they are then absorbed by mucosal cells, which helps to promote human metabolism and maintain health.