According to the theory of Hipocrates (3rd century BC) "all diseases begin in the intestines". It is now known that intestinal microorganisms participate in physiological processes such as: immune system functioning, detoxification, inflammation, neurotransmitter and vitamin production, nutrient absorption, hunger, and satiety signaling, carbohydrate and fat burning. Thus, a beneficial microbial flora is maintained by proper nutrition. Also, in the literature, there are microbiome-specific associations with different pathologies: attention deficit hyperactivity disorder (ADHD), asthma, autism, allergies, chronic fatigue, depression, anxiety, and diabetes. To prevent these pathologies, in the children's growth and development it must be considered multiple factors: the type of birth (natural or caesarean), genetics, general health, physical activity, sedentarism, sleep quality, and appropriate nutrition.