Integrating Nutrition and Mental Health: Mechanistic Pathways, Clinical Evidence, and Public Health Policy Implications

Mounting evidence reveals a critical intersection of mental health and nutrition, with dietary consumption and nutrient availability influencing cognitive function, mood, and risk for psychiatric illness. This review takes the field a step further by integrating mechanistic pathways, clinical trial data, and public health policy implications into a single framework that differs from earlier reviews. Mechanistically, nutrition affects neuroinflammation, oxidative stress, neurotransmitter synthesis, and the gut–brain axis. Key nutrients—omega-3 fatty acids, B-vitamins, minerals, and polyphenols—sustain neuronal integrity and modulate stress, whereas diets high in processed foods and added sugars make the individual more vulnerable to depression and anxiety. Clinical trials offer proof that dietary quality interventions, specifically Mediterranean-style or nutrient-dense diets, improve mental health outcomes, particularly in vulnerable populations. Importantly, nutrition-based interventions can complement psychiatric treatments and enhance prevention. Policy-level integration, including mental health-specific dietary guidelines and regionally relevant implementation protocols, has the potential to substantially reduce the global disease burden. Research priorities are posited in the form of longitudinal studies, mechanistic trials, and precision nutrition. By establishing nutrition as a preventable risk factor for mental health, this review insists on its inclusion in evidence-based clinical practice and public health policy worldwide.