From Food to Mood: Psychological and Psychiatric Impact of Diet in Bipolar Disorder

Bipolar disorder (BD) is a severe psychiatric illness characterized by recurrent mood episodes and significant psychosocial impairment. Emerging evidence supports a bidirectional link between diet and mental health, with growing interest in nutritional psychiatry. This narrative review examines the psychological and psychiatric impact of diet in BD, focusing on biological mechanisms (gut–brain axis, neuroinflammation, oxidative stress, neurotransmitter synthesis, and HPA axis dysregulation) and the role of specific dietary patterns, including Western, Mediterranean, ketogenic, and anti-inflammatory diets. Key micronutrients such as omega-3 fatty acids, B-vitamins, magnesium, and vitamin D are explored in relation to mood regulation. This review also addresses psychological factors, including emotional eating, disordered eating behaviors, and the symbolic meaning of food in BD. Furthermore, it highlights the integration of nutritional psychoeducation into psychotherapy, the impact of comorbidities (e.g., obesity, metabolic syndrome), and the role of lifestyle factors such as sleep and physical activity. Despite promising findings, current research is limited by methodological heterogeneity. Future perspectives should include interdisciplinary, personalized interventions that incorporate nutritional strategies into standard care for BD.