The article explores the complex relationship between gut microbiota, nutrition, and mental health, emphasizing the bidirectional interaction between the brain, gut, and gut microbiota. It highlights the role of the brain-gut-microbiota (BGM) system in influencing mental and brain health through nutrient absorption, cognitive processes, mood regulation, and neuroplasticity. The study discusses how nutrition impacts brain health, mental well-being, and cognitive functioning, with a focus on the effects of ultra-processed foods (UPF) on mental health. It also examines the neuroimmune, neuroendocrine, and vagus nerve pathways of the BGM system, detailing how dietary patterns influence gut microbiota composition, immune responses, and neuroinflammation. The article emphasizes the importance of a balanced diet rich in fiber, essential nutrients, and whole foods to support brain health and mental well-being. It also discusses the developmental origins of the BGM system, the impact of nutrition on brain development, and the role of lifestyle interventions in improving mental health outcomes. The study concludes that a holistic approach integrating nutrition, lifestyle, and clinical care is essential for enhancing mental health and overall well-being. The research underscores the need for interdisciplinary collaboration to better understand and address the complex interplay between nutrition, gut microbiota, and mental health.The article explores the complex relationship between gut microbiota, nutrition, and mental health, emphasizing the bidirectional interaction between the brain, gut, and gut microbiota. It highlights the role of the brain-gut-microbiota (BGM) system in influencing mental and brain health through nutrient absorption, cognitive processes, mood regulation, and neuroplasticity. The study discusses how nutrition impacts brain health, mental well-being, and cognitive functioning, with a focus on the effects of ultra-processed foods (UPF) on mental health. It also examines the neuroimmune, neuroendocrine, and vagus nerve pathways of the BGM system, detailing how dietary patterns influence gut microbiota composition, immune responses, and neuroinflammation. The article emphasizes the importance of a balanced diet rich in fiber, essential nutrients, and whole foods to support brain health and mental well-being. It also discusses the developmental origins of the BGM system, the impact of nutrition on brain development, and the role of lifestyle interventions in improving mental health outcomes. The study concludes that a holistic approach integrating nutrition, lifestyle, and clinical care is essential for enhancing mental health and overall well-being. The research underscores the need for interdisciplinary collaboration to better understand and address the complex interplay between nutrition, gut microbiota, and mental health.