Microbes accompany humans throughout their lives and participate in the physiological regulation of the host and is one of the key determinants of human health and disease. Intestinal microbiota affects human immune status, prevents colonization of pathogenic microorganisms, and has certain metabolic and nutritional functions. The infancy is called "the best window period for the development of intestinal microorganisms" and is the critical period for the establishment and stability of intestinal microbiota. Each person has their own unique makeup of gut microbes, like a person's fingerprint or identity card. The gut microbiome, which may play a key role in brain development and maintenance, is called the “microbiota-gut-brain axis”